WHARVES AND PIERS McGraw-Hill BookCompany Electrical World The Engineering andMining Journal Engineering Record Engineering News Railway Age G azo tte American Machinist Signal EnginGGr American Engineer El J ./.> Elevation, Outer End of Her- Side Elevation Fig. 1. Wooden Pier, Dept. of Docks, New York, N. Y. with a restricted amount of sap wood has increased greatly within the last few years. The opening of the Panama Canal has, however, brought Douglas fir into competition with yellow pine, on the Atlantic Coast. This lumber can be obtained entirely free from sap wood and can be 8 WHARVES AND PIERS sold profitably at much less than the price recently charged for southern long-leaf yellow pine of poorer quality. It is very desirable that the energy of moving vessels coming in contact with a wharf be absorbed by the elasticity of the structure rather than by its destruction or by the injury of the vessel. This is evident when we consider that a ship weighing 10,000 tons, moving at a rate of one mile an hour or about 1^ feet a second, has a kinetic energy of about 350 foot tons and for double this velocity the energy is nearly 1500 foot tons and that when such a moving ship comes in contact with a wharf this amount of work must be expended in distorting either the ship or the wharf. It is stated of a very large pier of concrete pile construction that its ability to withstand blows from vessels has been demonstrated and that in every case the plates of the steamers were the sufferers. The owners of ships will shun such a pier if possible and will use in preference one which is elastic and will not injure their vessels. Timber for wharves and piers has advantages over steel, stone, or concrete in the above respect. It also permits of greater rapidity of construction and more easy and rapid altera- tions, extensions, or removals. While timber wharves and piers are liable to destruction by fire, it is usually the freight on the pier which starts the fire and causes the greatest portion of the loss. The pier or wharf may, by using only timber of large cross section, be of the slow-burning type of construction and can be so designed that floating, burning materials, such as cotton bales, cannot get under it and that if in any way a fire obtains a hold under the deck it can be reached by the firemen and extinguished. Many instances are known o fires which destroyed the shed and all the freight on wooden pier but did not burn through the deck or injure the substructure in any way. No method of construction has been adopted, however, which will protect a Wooden pier from destruction by burning oil floating on the water. Several fires of this nature caused by the rupture of sub- INTRODUCTION 9 merged oil pipe-lines or of oil storage tanks near the water front have occurred, and have usually resulted in the destruction of all wooden piers in the area reached by the oil. Piers of the types shown in Figs. 73, 74 and 75 are not liable to this danger. Timber piles, unless creosoted, are uneconomical in water infested by marine borers except for temporary structures. Partially creosoted piles last only from fifteen to thirty years, as they are subject to the washing out of the preserva- tive and to the decay of the uncreosoted interior, and completely impregnated piles usually cost nearly as much as those of concrete. In many cities, however, there is enough sewage in the water to drive away the destructive marine animals, and in such places, where the bottom is suitable, wooden piles are cheaper than any other material for the foundations of piers and wharves; at any rate, for structures the commercial life of which will probably not exceed forty years. Wood Preservatives. Various forms of coal tar products are used to preserve wood in wharves and piers from destruc- tion by marine borers and from decay. Wood may be treated by the pressure process, in which the material is placed in a closed cylinder and after being treated with steam to remove the sap is then impregnated with the preservative under heavy pressure; by dipping in a tank containing the preservative; and by applying the preserva- tive with brushes. All methods render the timber most unpleasant to handle, as the preservatives are all irritating to the skin and eyes. Destructive marine animals of one form or another thrive in nearly all salt and brackish water harbors in this country and to the south of it. They are most active in warm waters, but the limnoria is so plentiful at Halifax that concrete piles from 75 to 90 feet in length were used in building steamship piers there, and Puget Sound is noted for the size and abundance of its teredos. Creosoted piles resist the action of these animals as long 10 WHARVES AND PIERS as a sufficient amount of the creosote remains in the wood, but sooner or later enough of the preservative washes out and the borers enter. On the Pacific Coast, where the teredo is very active, creosoted piles are said to have a life of one year for each pound of creosote to a cubic foot of timber. The usual practice is to impregnate the piles to a depth of about 2 inches. This, however, is not a complete protection, as the slightest perforation of the impregnated shell results in the entrance of the teredo and the destruc- tion of the interior portion. The more resinous the wood the more resistant it is to the entrance of the oil of creosote, and cases have been known of the destruction of piles by the entrance of teredos through the knots. The interior portion sometimes rots, though this can be largely pre- vented by coating the tops of the piles, after they are cut off, with some form of preservative. Complete impregna- tion of the pile is extremely expensive. Some kinds of timber, Douglas fir in particular, are very resistant to the entrance of creosote into the pores. It is extremely diffi- cult to obtain uniform penetration and in a creosoted pile structure some of the piles are much shorter lived than others. The permanence of the preservative and the durability of the wood after impregnation depends very largely on the nature and quality of the oil, and much atten- tion is at present being given to the study of this point and methods to ensure uniformity of penetration. In places where marine borers do not exist and where the portion, of the piles above low water is the only part which decays, a method by which only that portion of the pile could be impregnated would remove all the objection to wooden piling except that of the fire risk. Experiments are being made with some promise of success by one of the manufacturers of wood preservative to impregnate the upper portion of the piles for a distance of ten feet or more by lowering a cylinder closed at the top over the pile after it has been driven and cut off, fitting a tight collar between the lower end of the cylinder and the pile and then pumping INTRODUCTION 11 the preservative into the cylinder under heavy pressure. Attempts have been made to obtain the same object by boring a vertical hole in the centre of the pile at the top and filling it with preservative. This method, however, failed, as the preservative did not spread radially from the hole, but ran down the annual rings in the timber and only impregnated a core about the size of the hole. Decay can be prevented by creosoting by the pressure process, though some examples are known of the rotting out of the interior of 12-inch square timbers preserved by this method. Such treatment greatly increases the cost of the lumber, and it is not usually considered economical to use creosoted material for wooden wharves except in places like the foundation for shed posts, where it cannot be easily renewed. Treatment by the dipping process is cheaper, but still expensive on account of the equipment and handling required, and is open to the same objection as the pressure process in that the cutting of the lumber after treatment leaves portions of the material exposed to decay. That portion of a wooden wharf which is subject to rot, decays most rapidly at the points where moisture enters and does not dry out, such as at butt joints and where one timber bears on another. A brush coating of good preservative on all scarfs, butts, tenons, tops of rangers and stringers, and all other places where one timber rests on or against another and on all timber within five or six feet of the edge of a wharf or pier where it is exposed to spray and rain, is cheap, greatly increases the life of the timber, and makes the deterioration more uniform. One advantage of treating lumber is that the cheaper grades, containing a large amount of sap wood which, though it is nearly as strong as the heart, decays much more rapidly, can be made as durable as the more expen- sive grades. Concrete enters largely into the construction of piers and wharves. It has the advantage over wood in that it is not subject to decay or destruction by fire or marine borers. 12 WHARVES AND PIERS Up to the present time there has always been considerable uncertainty as to the durability of concrete in sea water, as there have been many failures and many successes and the reasons for success or failure have not in all cases been ascertained. The present-day knowledge of the subject may be summed up as follows. Well-made concrete which is constantly submerged in sea water and which has not been exposed to the washing action of water currents until it has hardened will not disintegrate. Most of the deterioration of concrete in sea water takes place on the exposed surface between high and low water in cold climates and is due principally to frost and the crystal- lization of salts and in less degree to the abrasion of floating timber and ice and to the action of waves. Such deteriora- tion may be easily and cheaply repaired by means of the cement gun or by properly secured patching. Disintegration can be largely prevented if sufficient care be taken in the selection of the cement, sand, and stone, in the mixing, depositing, the construction of the forms and the prevention of the action of waves or -currents on the concrete before it is hard. The cement should prefer- ably be low in alumina, and the sand and stone should be graded in size so as to give the densest and most impervious mixture possible, in order to prevent the entrance of the water into the mass and the consequent disruptive action of the frost and the crystallization of the salts from the sea water. This impermeability of the concrete is the most important element of durability and has been success- fully attained by the use of a large proportion of cement. One part of cement to one and one half parts of sand have given excellent results, while those with one part of cement to two parts of sand and more appear to be uncertain. Much greater reliability can be obtained by moulding the concrete on land, as is the case in concrete piles and in the great blocks of the New York bulkhead wall, than by depositing it in forms below high-water mark, where it is INTRODUCTION 13 difficult to prevent the washing action of the water before it has time to harden. Concrete deposited under water by tremie has in some cases been successful, but the diffi- culties in obtaining good work are numerous and there are so many examples of unsuccessful results following the use 6f this method that it is generally considered undesirable. Concrete Piles. -- The use of concrete piles and columns has made great strides within the past decade for situation where great permanency is desired and the marine borers render the use of timber piles, either with or without the use of preservative treatment, inadvisable. This applies particularly to piles. Much progress has been made within the last four or five years in increasing their length and in reducing the cost of fabrication and handling. Piles up to 106 feet in length. have been used where hard bottom was at great depth and concrete columns have been placed extending 45 feet below low water. The reinforced concrete columns mentioned above have been used to a considerable extent on the Pacific Coast, where they originated. They consist of a reinforced con- crete cylinder three or four feet in diameter, enlarged at the lower end to give a bearing of great area on hard bottom or a group of wooden piles. Concrete piles cost from three to four times as much as wooden piles of the same length, but in some places are cheaper than columns of concrete resting on and protecting clusters of wooden piles. They are somewhat wasteful of material, as the strength required for handling them with ordinary appliances is greater than that required for sup- porting the load after the pile is in place. They will support more load as a column than wooden piles in certain kinds of bottom, but on account of their weight will not support as much as a wooden pile where skin friction is relied upon for bearing power. Concrete sheet piles of various forms with and without tongues and grooves have been successfully used in many places. They have also been made with the interlocking 14 WHARVES AND PIERS portion of steel-sheet piling embedded in their edges, the cracks between the adjacent concrete portions of the piles being filled with grout to protect all portions of the steel from rust. Steel-sheet piles encased in concrete are also used, but are comparatively expensive. Stone masonry is so costly that it enters very little into the construction of wharves and piers at the present time except as a facing of walls of the most monumental char- acter, such as the New York bulkhead wall, and for pro- tective facing for concrete. Steel. Steel for bearing piles and sheet piles has been used to some extent, the latter mostly within the last few years, for wharf construction. Steel piles made of pipes such as are used for gas and water have been used for the ocean piers at Atlantic City, N. J., Old Orchard, Me., and Coney Island, N. Y., which were built twenty or thirty years ago. These piers are subject to severe wave action, and those at Atlantic City and Old Orchard corroded to such an extent in about ten years that they had to be rebuilt. The superstructures of these piers, as well as the piles, were very severely attacked by the rust. The piles of one of the piers at Coney Island, however, are said to have had a useful life of about twenty- five years. Steel sheet-piling without any protection except paint has been used for retaining walls for wharves in fresh water, notably in Bremen; at the entrance to the United States lock at Black Rock, Buffalo, N. Y.; at the Barge Canal Terminal at Rome, N. Y.; at Sandusky, O.; Hamilton and Toronto, Ont.; Duluth, Minn.; and in salt water at Jacksonville, Fla. It gives a very simple and cheap form of construction and can be arranged to be easily replaced if rusted to the danger point. The estimated rate of destruction by corrosion is so low that it is claimed that for a structure having an assumed commercial life of thirty to forty years* this material is more economical than wood or concrete in fresh water. INTRODUCTION 15 The rate of corrosion in water of the commercial steel of the present day is very uncertain and the action of the various factors which determine it are at present not entirely understood. It .is known, however, that corrosion cannot take place without oxygen and it is considered that steel buried in the ground, where whatever oxygen there is in the material in contact with the steel is soon exhausted, may be depended on to last indefinitely. Where steel is subject to currents or waves which bring fresh supplies of oxygen to the metal the corrosion is much more rapid than in still water. On the other hand steel in salt water is often covered with a dense growth of shell fish which par- tially protects it. In most cases the corrosion has been found much greater above low- water level than below it. This portion of a pile, exposed to alternate wetting and drying, can, like the sides of a ship, be protected by paint- ing, but the expense would be considerable. In most cases it has not been attempted and in others it has failed because the waves and spray washed the paint off before it had time to harden. It is well known that the rate of corrosion is much greater in salt than in fresh water, and it has also been ascertained that steel bars of different shapes have different rates of corrosion. A paper by B. H. Thwaite, an English engineer, published in 1880, gives as the result of experiments the following comparative rates for the corrosion of steel: Foul sea water 1944 Clear sea water . 0970 Foul river water 1133 Pure air or clear river water 0125 Air of manufacturing districts or sea air 1252 The above figures are the " coefficients of corrosion" W to be used in the formula Y = ^rf> where Y is the life of C Li the metal in years, W the weight in pounds per linear foot of steel bar exposed, and L the perimeter of the steel bar in feet. 16 WHARVES AND PIERS A steel plate yV inch thick, 12 inches wide, has a weight of 17.85 pounds per linear foot. If we assume that only one side of this plate is exposed to sea water, the perimeter so exposed would be one foot. Taking the highest coefficient given in the table the formula for the life of the plate would 17 85 be Y = in/f/i TT = 91 + years. A steel-sheet pile with x J- a web T 7 / required Face of Concrete S fee/ Washer Fig. 4. Bolt for Fastening Fenders to Concrete Walls. in the concrete and permits the easy removal of the bolt, Expansion bolts have the advantage of not. having to be held in place in the forms, and as the holes for them need not be drilled till after the wood is bored there is little time 42 WHARVES AND PIERS lost in locating the holes. They are better for stone masonry, however, than for concrete, as the holes need not be as deep. For concrete the shank of the bolt must be fitted with sleeves. Expansion bolts when properly put in place will hold in tension up to the full strength of the bolt at the base of thread, but it is somewhat difficult in ordinary work to obtain such results. SEWERS IN PIERS As it is undesirable to have sewers empty into the slips between piers it is necessary to support them in the sub- structures, as shown in Fig. 70. Sewer boxes of circular form for pile piers are made of creosoted wood-stave pipe with gal- vanized iron bands. Hatches should be provided at proper intervals to permit cleaning and inspection. Reinforced concrete pipe also affords a cheap and durable material for this purpose which can be easily and cheaply put in place. CHAPTER IV RETAINING WALLS FOR PIERS AND MARGINAL WHARVES FUNCTIONS OF WALLS FOR solid-filled piers and marginal wharves a retaining structure is required to support the earth or filling and must afford, either in itself or in combination with a plat- form of some kind, a vertical face of sufficient depth to permit vessels to lie close alongside. Such a structure must prevent erosion of the shore, withstand the impact of vessels, currents and waves, and resist overturning, sliding, and deformation by the earth or other filling with its sur- charge of merchandise. CALCULATION OF PRESSURES A wharf wall presents some features which are not present in ordinary retaining walls on land. These consist in the presence of water on both sides of the structure, the dimin- ished weight of the wall due to its submergence in the water, the variety of materials usually found in the filling, and the variation in the weight of the filling due to the fact that part of it is submerged and part not. The calculation of the pressures on such walls is therefore complex and subject to many more uncertainties than that of land walls. In some cases it is impossible. The two methods used in the Department of Docks in New York are given by S. W. Hoag in the Proceedings of the Municipal Engineers of the City of New York, 1905, as follows: "The conditions given are approximate cross-section of submerged or of non-submerged wall, submerged sections 44 WHARVES AND PIERS and non-submerged sections of riprap filling and of earth filling, and a surcharge of 1000 pounds per square foot (see Fig. 5). J jr x - / j / / < *:-. h / r r Sj / / / / / r d' h ?' f x r^x/v^vv x'/^> ^v^ ?y/!j^% x x ',/ 'srsrv* -"TO- Fig. 5. Method of Determining Pressures in Sea Walls, Dept. of Docks, New York, N. Y. " Erecting a perpendicular ad, laying off the prism of maximum thrust of riprap by the plane of rupture ae, prolonging the line ae to n and the corresponding prism for the superimposed submerged earth filling by the plane ek, RETAINING V/ALLS 45 which we shall prolong to ra, neglecting the change in plane of rupture for non-submerged earth filling, we find that the limit of surcharge to be considered at the surface grade is contained between the intercepts d and m. Considering now everything below mean high water as submerged and everything above mean high water as non-submerged, let us conduct the analysis on the following assumptions: " Let the weight of riprap in air be assumed at 107 Ib. per cu. ft. " Let the weight of submerged riprap be assumed at 70 Ib. per cu. ft. " Let the weight of earth filling in air be assumed at 110 Ib. per cu. ft. " Let the weight of submerged earth filling be assumed at 66 Ib. per cu. ft. " Let the surcharge be assumed at 1000 Ib. per sq. ft. " First. Determine the weight of the submerged earth filling cek, and replace it with a corresponding weight of submerged riprap. The top surface of the latter will then be cf'k. ' "Second. Determine the weight of the non-submerged earth filling cdmk and replace it with a volume of submerged riprap of equal weight, and allow it to take its position upon the first reduced volume of submerged riprap. The upper surface of this second volume will then be cd'hTmkf. " Third. Take the surcharge of 1000 Ib. per sq. ft. and erect upon the top surface d'h'l'm of this imaginary bank of submerged riprap a prism of submerged riprap of such a volume as shall equal in weight the surcharge; the upper surface of this third reduced volume will then be d"ti'l"m f . We now have the area a d"h"l"m r nea representing in volume all of the back filling used in exerting pressure against the wall reduced to one homogeneous material, namely, sub- merged riprap weighing 70 Ib. per cu. ft. But in order to avoid the complication arising from a consideration of the two planes of rupture ae and em, and as we have already reduced the back filling riprap, let us adhere to the plane 46 WHARVES AND PIERS of rupture for riprap, namely, an, and shift the material represented by the area enm to a new position to form part of the prism limited by the plane cm; we have, making h" the new position for d"V" the new position for kl' ', and m'm" the new position for mn, as the volume to be con- sidered, the weight of submerged riprap represented by the area a d"h"l'"m"na. " The centre of gravity of this area is found to be at g' ', and combining the weight of the mass through g' with its hori- zontal component, we find the horizontal thrust on the back of the wall to be 27,000 Ib. applied at the point p. Combining this thrust with the weight of the wall repre- sented by the vertical line 65,300 Ib. through its centre of gravity, we obtain the resultant, 71,000 Ib., which passes through the base at the point r. "In determining the centre of gravity of the wall section it is of course necessary to consider the reduction in weight due to displacement below mean high water of the two materials, concrete and granite, which enter into its con- struction, the weight of the non-submerged portion above mean high water, the weight of the submerged riprap on the steps in the rear of the wall, the weight of the superimposed volume of non-submerged riprap and of earth filling." The other method, which may be simple in cases where riprap does not form part of the filling, is illustrated in Fig. 6 and the description is as follows: "Applying the analysis to the same section of wall, and laying off the planes of rupture for riprap ae and for submerged earth em, as before, let us, first, consider the pressure of the volume represented by the area enme with its super- imposed surcharge. Combining the centres of gravity of the three different densities represented, that is, the sub- merged earth filling efk, the non-submerged earth filling fhmk, and the surcharge hm, 13,600 Ib., we obtain the re- sultant weight, 23,800 Ib., through the resultant centre of gravity g'" . Combining this weight as a vertical force through g'" with its horizontal component, we get the RETAINING WALLS 47 resultant thrust on eh, from which we obtain the hori- zontal thrust, 18,000 lb., against the vertical plane eh at the point p. " Again, in the area bdhe combining the weights and centres of gravity of the different materials, namely, submerged riprap bee, submerged earth filling cfe, non-submerged earth filling cdhf, and superimposed surcharge dh equal to 12,000 lb., we obtain the resultant weight 28,600 lb. through the resultant centre of gravity g" . Com- bining this force with the horizontal thrust 18,000 lb., we obtain the direction of the resultant which strikes the line ad at the point p" with a horizontal thrust of 18,000 lb. "Finally, deter- mining the weight and centre of gravity of the submerged volume of riprap represented by the area abe and decomposing the resultant thrust with this weight 12,430 lb. as the vertical compo- nent through the centre of gravity g f ', we obtain the hori- zontal thrust 5400 lb. applied at the point p" r . "Now combining the two horizontal thrusts at p" and p" 1 ', determine the resultant horizontal thrust 23,400 lb. ap- plied at a point p"" ', and combining the resultant horizontal thrust with the weight of the wall, determined as before through its centre of gravity g, we get the resultant thrust on the base of the wall 70,000 lb. applied at the point r." A comparison of the two methods shows a very close agreement both in the amount, direction, and point of application r of the resultant thrust. Fig. 6. Earlier Method of Determining Pres- sures in Sea Walls. 48 WHARVES AND PIERS Another good article on this subject may be found in Merriman's American Civil Engineer Pocket Book. The horizontal resistance of sheet piling in earth is a subject on which there is little in engineering literature in the English language, but the matter is well treated in an article by Professor Wolmar Fellenius in Engineering Record of Sept. 20, 1913. This article also treats of wharf walls of the platform type. Mud Waves. Wherever there is mud which can move as a fluid behind a retaining structure the filling will produce a wave or elevation of the surface of such material. Mud acts like any other fluid against a retaining structure except that it exerts a pressure greater than water. It has no angle of repose and therefore will exert a much greater pressure than earth or any similar non-fluid filling. If filling is deposited on mud from the shore outwards toward a retaining wall it will push the mud wave ahead of it and increase the elevation of the mud pressing against the wall and may thus increase the pressure so much above that of the filling for which the wall is designed as to destroy the structure. This has happened in practice so frequently that the matter demands the greatest emphasis. The remedy is to deposit the filling from the wall toward the shore. In this way the mud is driven away from the wall and the increasing pressure due to the increasing height of the wave is resisted by the increasing width of the bank of filling. The depositing of the filling in this manner is usually much more inconvenient and expensive than depositing it from the shore outward, in that it is often necessary to construct temporary roadways for the purpose and this may be one of the reasons why this most necessary pre- caution is so often neglected. GRAVITY WALLS Gravity walls may be of riprap, cribwork, stone masonry, concrete blocks, mass concrete, caissons of concrete, steel, or wood, or various combinations of these materials. RETAINING WALLS 49 Walls which depend on gravity alone for their stability are generally costly as compared to other types, especially where they have to be constructed in the water. Tie-rods and anchors placed in the rear are often used to assist in taking up the thrust of the filling and permit the reduction of the cross-sectional area of the wall. Gravity walls are particularly suited to rock or other hard bottoms where piles cannot be driven. Where the bottom has not sufficient bearing, however, and piles can be driven, a gravity wall may be placed on piles cut off at the proper height. When a wall of stone or concrete blocks is built with a pile foun- dation some method of obtaining a uniform bearing on all the piles such as is described on pages 90 and 122 should be used. The outshore face, of retaining walls should be sloped back in order to bring the centre of gravity as near the heel as possible, thus increasing the resistance to over- turning and decreasing the necessary cross-section. Sloping the face, however, makes it impossible for vessels to lie with their upper parts close against the top of the wall. Where piers for the use of large vessels are built in front of the wall and only small vessels are moored parallel to it, this does not make much difference. For example, in New York City, the slips are narrow and scows and lighters with shallow draught lie at the wall, the large steamships being berthed alongside piers with their bows inshore. The walls are therefore designed with as much slope as is possible with the bows of the steamers coming close up against them. Where large steamers are to lie alongside a wall a nearly vertical face is required, and on a sloping shore it is usually cheaper to place the wall at the rear of a marginal platform, as by such an arrangement its cross- section may be greatly reduced. Riprap. A bank of riprap forms a simple form of re- taining wall which cannot be overturned and strongly resists movement by sliding. It is often very much cheaper than a gravity wall of concrete or stone masonry. The 50 WHARVES AND PIERS sloping sides of such a bank, however, do not permit its use as a wharf unless it is combined with some form of structure which has a vertical face. Where the depth of water is greater than that required for wharfage such a bank of riprap may be employed to take the greater part of earth-thrust, a masonry wall being Fig. 7. Riprap Wall with Upper Portion of Granite Masonry, New York, N. Y. placed on the front edge to provide the necessary vertical face. As this comparatively expensive facing need be only deep enough to serve the requirements of shipping, such a combination results in a large saving over a masonry wall of the full depth. A good example is shown in Fig. 7 built in New York near the Battery about fifty years ago. When used under a pile platform, a riprap wall reduces RETAINING WALLS 51 the required width of the platform, takes a major portion of the earth-thrust, reduces the stresses in the bracing piles or tie rods, and gives lateral support and stiffness to the piles. A design for a very inexpensive wall of this type is shown in Fig. 8. A bank of riprap has a safe angle of repose, when sub- merged, of 1 on 1 or 1 on 1J, and as this is much steeper M.H.W. M.L.W. Fig. 8. Design for a Cheap Riprap Wall with Pile Platform. than the angle of repose of submerged earth, it exerts much less thrust against a vertical surface than other forms of filling. When, therefore, it is placed behind a masonry wall or a line of sheet piling, it reduces the required section of masonry and the stresses in the ties or bracing piles used to support sheet piling. In front of a retaining structure it serves the same purpose, though not so efficiently. A notable modern example of a riprap wall is that recently built in San Francisco and illustrated in Fig. 9. In this 52 WHARVES AND PIERS case the mud was dredged to about 36 feet below low water. The main part of the wall is composed of riprap, as shown in the drawing. A retaining wall of mass concrete 13 feet high, supported on wooden piles 60 feet from the face of the wall, extends from low water to the street level and forms the upper part of the retaining structure, making a smooth and tight coping for the riprap. A platform on concrete piles covers the outer slope of the riprap and forms the wharf at which vessels are moored. In order to provide an elastic deck which would not be injured by the settlement of the riprap and piles in the mud bottom, the beams of the platform are of steel and the joists and deck plank of wood. The wooden piles are protected from the marine borers by the riprap. The wall built in New art* ;i !! , 7 A ; ; ... . York in Places where the mud is very deep, Fig. 9 Riprap Wall with Concrete Pile described on page 88 Platform, San Francisco, Cal. is another example of a wall in which riprap plays a leading part. Crib work. One of the commonest forms of retaining structure is that of a stone-filled timber crib work. Crib- work is best suited for rock or other hard bottom where piles cannot be driven, but has been used on the Harlem River in New York City even in deep mud. In its least expensive form, consisting of a cellular box built of round logs notched together with the axe and fastened with spikes or drift bolts, it is in many localities one of the cheapest forms of retaining structure. In New York it costs about 8 cents a cubic foot, exclusive of dredging. One of its advantages is that it may be built entirely with hand tools and does not require any expensive equipment. It is, however, subject to decay above half tide on the sea RETAINING WALLS 53 coast and above low-water level in non-tidal haroors, and every twelve or fifteen years the decayed portion must be torn down, rebuilt, and refilled. A cribwork wall of round logs, as built by the New York Dock Department, is shown in Fig. 10. The structure is built floating in the water, usually over or near the site where it is to be located. The bottom, if of rock, is cleared Fig. 10. Crib Wall of Round Logs, New York, N. Y. of all overlying mud and the cross-section carefully de- termined. The bottom of the crib is then laid out to fit the surface of the rock. If the bottom is of earth it is dredged as smooth as possible, dredges of the ladder type being superior for this purpose. A layer of gravel or broken stone may be deposited and smoothed off with straight edges to level up small irregularities in the bottom. On sloping rock, sliding may be prevented by heavy iron dowels. The cribs are built with cells 8 feet long and 5 feet wide, a sufficient number of them being floored over. 54 WHARVES AND PIERS As the structure is built up, the floored cells are filled with stone and the structure sinks. When it is high enough to reach above low water it is carefully adjusted in location and the sinking of the structure is completed and all the cells filled. As soon as the crib settles and conforms to the bottom the portion above the water is completed. The face is built of sawed lumber above low tide to give a smooth surface and is protected by half-round oak fenders. The longitudinal logs should be not less than 6 inches in diameter at the point and not less than 50 feet long. They should have long laps where they are spliced. The trans- verse logs should be not less than 10 inches in diameter at the front in the upper portion which is subject to decay and 8 inches in the other portion. Dock spikes of ample size to allow for rust should be liberally used at all inter- sections. Such cribs usually require a width of not less than 16 feet at the top for heights up to 20 feet and may be from 18 to 25 feet wide for greater depths. The portion below the limit of decay may be made wider than that above, the part which has to be renewed being thus reduced to a minimum. Cribs of this construction have been used for retaining walls for solid-filled piers in soft mud of great depth, but usually some other form of wall will be found cheaper and more suitable for such locations. Where appearances are important such structures, if of large section, are usually unsatisfactory. From their very nature they are mere baskets, more or less loose in the joints, and they are liable to bulge both vertically and horizontally, to tip forward or backward, to shrink verti- cally, and unless the bottom is very carefully prepared they will sink into it more or less. Fig. 11 shows typical sections of large, round-log cribs, as built by the C. R. R. of N. J. at Communipaw, Jersey City, N. J. They are from 30 to 50 feet deep and are founded on hardpan. In these cribs vertical logs were placed in the corners of the pockets to prevent vertical RETAINING WALLS 55 shrinkage and the floored pockets are continuous from front to rear, instead of alternating, as in the previous ex- ample. Where it was expected that mud would flow into the trench, stone filling was deposited as soon as the dredg- *~- >K Cro ss - Section of Crib Section A-A Section B-B Section C'C Section D'D Fig. 11. Crib Wall of Round Logs, C. R. R. of N. J., Jersey City, N. J. ing was completed and the crib placed on this layer of stone. On the New York Barge Canal cribwork wharves were built with concrete walls on the outer edge from the water line up, as shown in Fig. 12. A large proportion of the total weight of the structures was in these concrete walls and some of those on ordinary earth bottom tipped forward as soon as the concrete was deposited and kept tipping as 56 WHARVES AND PIERS often as more concrete was added. Such action may be partly prevented by supporting the cribs on piles, by making the lowest tier of longitudinal logs continuous, thus increasing the bearing surface, and by temporarily loading the crib with stone or earth and completing the earth filling as far as possible before building the concrete wall. The lowest tier of transverse logs in these cribs was laid close together and the speci- fications required that the courses of logs should lay up not less than 10 inches centre to centre and that logs at joints should have two parallel faces not less than 6 inches wide. More stable cribwork can be made, but with consider- ably increased expense, by accurately dressing the joints, and still better results can be obtained by using Fig. 12. Crib Wall, with Upper For- sawed timber for the cross tion of Concrete, New York State tieg Qr for both crogs tieg and longitudinals and by bolting vertical timbers in the corners of the pockets. A crib wall for a large coal pier built at Duluth, in 1909, is shown in Fig. 13. The site of the pier was a sand bank, with its top 6 to 8 feet below water containing layers of clay. The bottom was dredged to a depth of 26 feet for the crib, which was of sawed lumber 21 feet wide with tight front and rear walls of 10-inch by 12-inch timbers and was divided into pockets 6 feet square. The top of the crib was 6 inches below mean low- water level. Piles were driven to support the reinforced concrete wall which sur- mounted the crib, in order to provide against settlement. The wall was tied to piles driven in the filling 40 feet RETAINING WALLS 57 from the rear face of the crib by 1J rods spaced 24 feet apart. This pier carried a heavy surcharge of coal piled on its surface. The crib wall surrounding an ore-pier shown in Fig. 14 was built at Two Harbors, Minn., at about the same date. The two rows of cribs were surmounted by heavy concrete footing walls resting on piles driven inside the cribs and carrying the columns of the ore bins. This structure is notable for the fact that the work, which included the set- ting of forms and de- positing concrete under water, was done in the winter time in a very cold climate and for the driving of foundation piles at very close inter- vals in a rockfilled crib. There were two rows of cribs of sawed lumber 16 feet wide placed about Fig. 13. Crib Wall of Sawed Lumber with Upper Portion of Concrete, Duluth, Minn. 22 feet apart. The cribs were tied together with timber walls, thus making a narrow pier about 55 feet wide. The tops of the cribs were placed at 4.5 feet and the tops of the piles were cut off at 3.5 feet below low water. A sheet of burlap was placed on the top of the piles to prevent the cement being washed out of the concrete. Forms were set on the cribs enclosing an area of about 18 feet by 50 feet and the water inside the forms heated to 45 degrees Fahr. by means of steam under 60 pounds, pressure supplied through a hose. The concrete, mixed in the proportion of 1 : 2 : 4, was deposited by bottom dump buckets to a height of 6 inches above water. The 58 WHARVES AND PIERS upper portion of the concrete was then completed with a 1 : 2f : 5 mixture. A layer of reinforcement was placed under the bottom of this upper course of concrete, and steel dowels were placed in the lower course to provide a secure bond between the two. The maximum load on the piles under the footings was 24 tons. The space between the cribs was filled with stone to give additional stability and rigidity for the structure, which had to withstand severe stresses from the impact of vessels and from the stopping of heavy ore trains on the superstructure. In this type of pier the function of the cribwork is merely to retain the filling i^ig. 14. Crib Wall of Sawed Lumber with Upper Portion of Concrete, Two Harbors, Minn. which affords lateral support to the piles. In piers of more recent date described further on sheet piling is sub- stituted for the cribwork. Another type of large, sawed-lumber crib of more recent design, shown in Fig. 15, was built at the Barge Canal Terminal at Buffalo. Here the water was deep and the bottom of rock or hard material. Where there was rock it was levelled off with broken stone. The cribs extended to 22 feet below mean low-water level and on them was placed a layer of concrete blocks extending one foot above the water and on these was built a mass-concrete wall. Though the weight of this wall was small in proportion to the total weight of the structure the specifications required that the crib should be allowed ample time to settle and that it should be levelled up with additional timber on the top if necessary before the concrete blocks were placed, RETAINING WALLS 59 but did not require that any filling be deposited before building the wall. No tie rods were used in this structure. Similar construction was employed at Oswego, N.Y., in which type additional stiffness was supplied by vertical timbers in the corners r g w of the pockets. The pockets in this crib were 10 feet by 7 feet 6 inches in area and the rear face of the crib was built in steps, as shown in Fig. 16. There were 350 feet more lumber per linear foot of wall in this design than in that of Buffalo and 153 pounds more steel fastenings, which made a very considerable difference in the cost. The stiffness and Stability of Cribwork Fig. 15. Crib Wall, of Sawed Lumber with may also be increased Upper Portion of Concrete, Barge Canal by filling some or all rermina1 ' Buffal ' N ' Y " of the pockets with concrete, as in the wall of the North German Lloyd Steamship Co., at their pier at Hoboken, N. J., shown in Fig. 17. The cribwork was founded on piles driven through mud to rock and cut off at 22 feet below mean low water. It was built of sawed lumber with pockets 10 feet square filled with 1: 2: 5: concrete deposited under water by means of a bottom opening bucket and was surmounted by a stone masonry wall with mass concrete backing. This method of construction permitted an examination of the concrete, which was found to be sound and strong. Riprap was used in front and in rear of the cribwork to aid in resisting the thrust 60 WHARVES AND PIERS of the filling, and cobble was used to consolidate the mud and to give lateral support to the piles. Corner and di- agonal braces were used in the pockets to prevent distortion of the cribwork while it was being filled. 'f*26 Screw Both countersunk or> face ofCr/'b Fig. 16. Crib Wall of Sawed Lumber with Upper Portion of Concrete, Barge Canal Terminal, Oswego, N. Y. At Depot Harbor, Ont., the upper portion of a timber crib wall which had decayed was replaced in 1904 with new cribwork made of 12-inch square reinforced concrete logs as shown in Fig. 18. Table II on page 18 gives a ready means of estimating the relative economy of this method. The lower portion was built of round timber in the usual manner. The main concrete logs were 20 feet long and had 2J-inch holes moulded in them at varying distances RETAINING WALLS 61 apart, arranged to allow dowels or bolts passing from top to bottom of the face of the concrete crib to be inserted after the holes were filled with grout. In the rear the cribwork was stepped and the members fastened together with screw bolts. The cross ties were dovetailed into facing pieces and short pieces inserted to fill the spaces between their ends and make the facing solid. Concrete mixed in the proportion of 1: 2: 3 was used with 1^-inch Floor Line Bulkhead Shed. Concrete, l : 2-4. Founds t ion for Cross- Walls > f>nd. ,-^f^ , Portland Concrete 1 : 2'-S v,^>\ ffi^j [ (Cornerfosise *' 6' every 30' Cobble Stones. 30' Fig. 17. Crib Wall with Concrete Filling, North German Lloyd Co., Hoboken, N. J. stone. A similar construction was specified for a 2400- foot break- water at Port Colburne. Quarried Stone Walls. In some places where quarried stone is cheap and the bottom hard and reliable this material may be used economically. It requires, however, careful levelling of the bottom with gravel or broken stone, expensive floating derricks of large capacity, and a considerable amount of work by divers. A good example of a quarried stone wall built in Boston in 1910 is shown in Fig. 19. The pier which this wall surrounds is situated near large granite quarries located on the shore and suitable floating derricks were available. 62 WHARVES AND PIERS The fact that the climate in Boston is severe and the tidal range is unusually large and that there had been many failures of concrete between high and low water may have had considerable influence in the choice of granite instead of concrete. Concrete Block Walls. Where concrete blocks are cheaper than quarried stone they may be used in a similar %-4 e r rt ~$ -Stf" fed Part- Elevation. Fig. 18. Crib Wall of Reinforced Concrete, Depot Harbor, Ont. manner, as shown in Fig. 20. The large concrete blocks in this wall are of 70 tons, weight. The portion above low- water level was made of granite with concrete backing, as concrete was not considered sufficiently durable for a work of such a monumental character. Riprap was placed behind the wall to reduce the thrust of the filling and the rock bottom was levelled off with concrete in bags placed by divers, with a top coat of gravel concrete worked smooth by means of heavy straight edges. The water at some places where this wall was built is 36 feet deep at mean low tide. RETAINING WALLS 63 A wall of blocks on piles is shown in Fig. 21. This type of wall is used in New York, where the piles can reach rock and where the bottom is sufficiently firm to prevent any horizontal movement of the piles. The bottom is dredged to a depth of 20 feet and the piles cut off at 15 feet. Any soft material is pumped or washed out and the space between them filled with cobble to the top of the piles. A concrete mattress as described on page 90 is placed on the heads of the piles just before the base blocks M.L.W. f O v - -*'.': vv; Y>. T,'.N .'.. ^"^A-^- : - ?'" : ./v Fig. 19. Granite Masonry Wall, Commonwealth Pier No. 6, Boston, Mass. are set. Riprap is placed behind the wall to diminish the earth-thrust and in front of it to aid in resisting the hori- zontal pressure. A very heavy wall of hollow concrete blocks filled with concrete and stone is now under construction at Halifax, N. S. This wall forms the retaining structure for a mar- ginal landing wharf for the largest ocean steamships, also for a solid-filled pier, aggregating some 6500 feet in length. It is planned to build, eventually, five more piers of similar construction. The depth of water at the face of the wall, as designed, varies from 45 feet at low tide for the major 64 WHARVES AND PIERS portion to 30 feet for a small part where the rock excavation for greater depths would be excessive. Among the conditions under which this wall is being built are the presence of rock over the entire site at depths Fig. 20. Concrete Block Wall on Rock, West 52nd St., New York, N. Y. of from 15 to over 60 feet, a location exposed to heavy swells, a large amount of waste rock and earth available for filling, and the impossibility of driving piles on account of the rock bottom. Speed and the carrying on of the work during the winter were among the requirements. Five general types of structure were considered in adopt- ing the chosen design: (1) concrete block walls with mass- RETAINING WALLS 65 concrete filling; (2) concrete caissons, with concrete bottoms, floated into place; (3) a solid block wall; (4) a concrete platform on concrete columns; (5) a wall of cellular concrete blocks. Fig. 21. Concrete Block Wall on Piles East 102nd St., New York, N. Y. The first plan involved difficulties in preparing the bottom and required expensive temporary staging; the second required expensive plant for launching, winter work would have been impossible, and it would have been difficult to make a good bond between the caissons and the bottom; the third plan had the same objections as to the bottom and plant; the fourth plan involved risk of injury during 66 WHARVES AND PIERS construction and would have cost about as much as the fifth, which was cheaper than the first three. 895hell3 af-22-0'- - -*i< 3/-O-* to.' 1 . ..'0 s'.? a^S *\ \ \ . /] o . a i V Section C-C Details of Concrete Block Plan Fig. 22. Wall of Hollow Concrete Blocks, Halifax, N. S. The adopted design consists of stacks of cellular concrete blocks, 31 feet long, 22 feet wide, and 4 feet high, weighing about 60 tons, reinforced against handling stresses and RETAINING WALLS 67 those existing when the filling is completed. These blocks are placed on the prepared foundation by a very large locomotive crane operating on tracks placed on the stacks of blocks already in place. They are kept in vertical alignment by reinforced concrete guides placed in triangular grooves formed in the sides of the blocks. After a stack of blocks is in place all the pockets in the lower layer are filled with concrete and those in the second layer are filled half full. Circular holes extending through all the blocks of a tier are then filled with grout, thus filling and bonding the horizontal joints between the blocks. Old rails are placed in some of the grout holes to strengthen the bond between the layers of blocks. The front row and the middle transverse rows of pockets in each block are also filled to the top with concrete, making a solid concrete buttress in each tier. The other pockets are filled with rock and sand. The two upper layers of blocks were made narrower than those below and a mass-concrete wall was carried up behind a granite facing from low water to the grade of the filling. Granite was used, as previous efforts to obtain concrete proof against destruction by frost and sea water between high and low tide in the extreme climate of this locality had been unsuccessful. A bank of riprap was placed in the rear of the wall to reduce the pressure of the filling. The bottom is prepared in several ways, according to the height of the rock. Where the latter is above elevation 45 feet below low water, the rock is blasted off and concrete pedestals laid under the corners of the blocks by means of a large diving bell which permits accurate work and thorough inspection. Where the rock lies far below the 45-foot depth a rubble mound is placed and allowed to settle for a year before the concrete pedestals are laid on it, as described above. Where the rock is only a few feet below the bottom of the blocks a mass concrete foundation is laid under water in a steel-sheet pile cofferdam. Under these 68 WHARVES AND PIERS . conditions the pedestals are also laid and levelled off under water. Design B -Reinforced -Concrete Caisson Floored toPosifion Design A Concrete Blockwork with Mass Concrete Heart Design C -Solid Block Wall Section of Columns Design D - Reinforced-Concrete Deck on Cylinders Fig. 23. Rejected Designs for Wharf Wall, Halifax, N. S. The advantages of the chosen design are that it permits the moulding of the blocks in the air, the rejection of all imperfect concrete, rapid construction, requires compara- tively small plant, no temporary staging, and permits the depositing of concrete under water in a permanent form RETAINING WALLS 69 under the best conditions for such work. The concrete in the lower pockets makes a strong, uniform bearing for the wall on the foundation and gives a strong bond between the two. The stacks of blocks not being connected, any vertical settlement which may take place during construc- tion as well as expansion and contraction both vertically and horizontally is free to take place. A considerable portion of the wall has been completed and the methods described are reported to give most satis- factory results in rapidity of construction and accuracy of alignment and levelling of the stacks of blocks. Mass-concrete Walls. Walls of mass concrete may be built in cofferdams where located in the water, and, in places where the slips or basins are to be excavated in the land and the water can be excluded, they may be built in sheeted excavations. Such walls may also be built in submerged forms, the concrete being deposited in the water by means of a tremie. The latter method has had many failures caused by the washing out of the cement from the concrete, and those that have been successful, for the portion under water, have in numerous cases not resisted the action of frost between high and low tide. A wall of this type constructed in a cofferdam is shown in Fig. 24. The depth of water was 25 feet at mean low tide. The cofferdam was somewhat difficult to maintain and the difference in cost between that and the block walls was so small that the block type was built in subsequent sections under similar conditions. The New York State Barge Canal affords many examples of mass-concrete walls built in the dry or in cofferdams. Fig. 25 shows the general form adopted for retaining walls for the canal banks, where no provision is made for sur- charge of cargo. A wall 44 feet in height and 2005 feet long was built of mass concrete in a sheeted and braced trench at Oak- land, California, as illustrated in Fig. 26. The facing is of richer concrete than the main portion of the wall in order 70 WHARVES AND PIERS to make this portion more impervious and so more resistant to the action of sea water. The fender piles are stepped in sockets cast in the lower portion of the wall and fastened by bolts extending through the wall in a 2-inch pipe in order Fig. 24. Mass Concrete Wall, East 116th St., New York, N. Y. to facilitate renewal. The earth inside the trench was removed by the hydraulic method, water being pumped from the harbor to a monitor, the earth, as it was loosened, sluiced to a sump and pumped out to the deeper portions of the harbor. The earth outside the wall was dredged out after the wall was completed. RETAINING WALLS 71 A good example of mass-concrete walls supported on piles, 29 feet high and extending 17 feet below mean low water T Fig. 25. Mass Concrete Walls, New York State Barge Canal. with a platform on piles as shown in Fig. 27 was recently constructed in San Diego, Cal. The bottom was excavated on a slope under the platform and a depth of 20 feet obtained at the face of the wharf, which was 25 feet wide. Riprap was used to prevent erosion ^ ^n^sedsurfa^ of the earth slope and to assist some- what in taking the thrust of the filling. Floating Caissons. - - Retaining walls built of caissons or boxes of wood, steel, or reinforced concrete, floated into place and then filled with various materials, have been built in some places. Two such walls in Denmark have interesting and unique features which might be used in this country. One 3300 feet long built in Copenhagen for a harbor basin is shown in Fig. 28. There are twenty-two reinforced concrete caissons made of a 1: 2: 3 mixture, each 162 feet long, 32 feet high, and 16 feet wide, which were built in a temporary 5. 26. Mass Concrete Wall, Oakland, Cal. 72 WHARVES AND PIERS dry-dock large enough to contain three at one time. The front walls are 10 J inches thick, those at the ends of the caissons 13| inches and the partitions only 7| inches. The depth of water at the front of the wall is 31 feet. The most interesting feature is the granite-faced wall extending from just above the water level to the top, which projects in front of the face of the caissons and protects them from the impact of vessels. The portion of the wall subject to freezing is protected by a thin facing of granite. In a similar wall built several years previously at Norre Sundby <5'^V^ 6 '- 6 "^>- lo ^ 6 L ^ ff4-/,sf/^ \ r Concrete Wa/T^ : Drain Hole 2'Dia> :: ; u; : Part EleywHon of Bulkhead j Fig. 27. Mass Concrete Wall, with Concrete Pile Platform, San Diego, Cal. in water 24| feet deep the exterior walls were notable for their extreme thinness, being only 5.1 inches thick at the bottom and 3.5 inches at the top. The caissons in this case were built on shore and launched by means of slipways. In both walls the caissons were filled with sand. Another example in which the walls are much thicker is that of the wharf walls of the new Welland Canal shown in Fig. 29. The caissons, which were 110 feet long, 38 feet wide, and 34 feet high, were open at the bottom but were fitted with temporary wooden bottoms to keep them afloat while they were towed to the site and sunk. They were built in floating pontoons which were arranged so that they could be taken apart and removed as soon as the RETAINING WALLS 73 caissons would float. As the stresses in the walls while afloat were much greater than after the caissons were in B Z& SECTION CC ^wr T . 2JO* __>) SECTION AA A SECTION BB Fig. 28. Wall of Concrete Caissons, Copenhagen, Denmark. place and filled with stone, the pockets were braced during transportation with timber, which, with the wooden bottoms, was removed as soon as the caissons were in place and used over and over. The caissons rested on windrows of stone 74 WHARVES AND PIERS placed on the dredged bottom under the longitudinal walls, and, after the temporary wooden bottom and bracing were removed, they were filled with dredged material. The outer edge of the row of caissons was surmounted by a mass-concrete wall built after settlement ceased. Fifty- three such cribs were built, and their great number made r B IIO'A'- Plan Interior Wall- & HLp && Section A-A Section B'B Secfion Showing Method of Racing Earth Fill Fig. 29. Wall of Concrete Caissons, Welland Canal, Ont. this form of construction economical. The most notable feature of this wall was the saving in concrete due to the ingenious and novel use of temporary wooden bottoms and bracing to resist the stresses while the caissons were being floated into position. It is stated that certain features of this design have been patented. A wall at Victoria, B. C., of reinforced concrete caissons or cribs, as they are locally designated, in which the bottoms of the caissons were of concrete and the walls sufficiently RETAINING WALLS 75 strong to withstand the water pressure when the caissons were afloat, is shown in Fig. 30. In this case the cribs were 85 feet long, 35 feet wide, and 39 feet high and the outer walls were 20 inches thick. They were braced with two longitudinal walls and with transverse walls every 10 feet. Additional deep beams between the transverse walls dis- tribute the pressure of the mass-concrete wall, 12 feet high and 16 feet above the water, which is built on top of the caisr K ..=....-., Q >- ^ I Longitudinal Section of Crib 1. 0.0 Section of Pier Fig. 30. Wall of Concrete Caissons, Victoria, B. C. sons. The cribs drew 28 feet of water when launched. The first ones were built in a floating dry dock, which was wrecked by premature flooding, and the later ones were constructed on a marine railway. These cribs, fifty-four in number, were used for enclosing solid-filled piers 800 to 1000 feet long and 250 feet wide in water having a maximum depth of 65 feet, and a novel feature in their construction was the preparation of the stone mound foundation on which the caissons rest. Large stone was deposited by deck scows, which slid their load 76 WHARVES AND PIERS overboard when water was admitted to longitudinal com- partments located along the sides of the hulls, to an eleva- tion of 36 feet below the water surface. Any rock projecting above this level was removed with a clamshell or orange- peel dredge bucket. The mound was then levelled up with gravel to elevation -35 and the gravel smoothed off by means of a plough suspended from a pile trestle driven into the riprap. The plough was a heavily braced timber structure, weighted with stone and having a pointed end shod with iron. It was hung by rods from beams arranged to move along the top of the trestle-work and when adjusted at the proper height it was hauled along the trestle, ploughing off any gravel above the required elevation. A comparison of the two foregoing cases is interesting. Reinforced concrete caissons for a breakwater at Algoma, Wis., 24 feet long, 15 feet wide, and 12 feet, 4 inches high were built by day labor for $17.66 a cubic yard for the concrete. The wall of caissons with pile foundation, con- crete filling, and superstructure cost $75.67 per linear foot. RELIEVING PLATFORM WALLS Relieving platform walls may be defined as those in which a platform on piles, in combination with banks of riprap, masonry walls, or lines of sheet piling forms a part of the structure and relieves the wall itself of the pressure of the live load and of any filling on the top of the platform, and of a part of the horizontal pressure of the filling beneath. The platform may be located at or near the level of low water or may form the deck of the wharf. The main object of the platform in retaining structures is to diminish the cost by the elimination or reduction of the thrust which is the necessary accompaniment of any wall which has a vertical facing on the front edge for the whole depth required by shipping. This object is attained in two ways: first by building the platform over a sloping bank, either natural or artificial, having its face at a safe RETAINING WALLS 77 angle of repose, and second, by placing the platform behind a wall of masonry or sheet piling. If the first method is used the platform may be placed over a bank of riprap which retains the filling, as in Fig. 32 or, if the wall be built inside the natural shore line, it may be placed over a dredged slope, protected against erosion by a revetment of stone, as in Fig. 37. In some cases such a platform has been built over an existing sloping shore without any dredging or revetment. A low wall of masonry or sheet piling may be placed at the rear of the platform in order to reduce the width of the latter and to provide a tight bulkhead to retain the filling at a point where the riprap is thin. This type of wall is particularly suitable for tidal waters where the range of tide is not too great, but platform walls of the first type are open to the same objections that apply to any wooden structure in waters where marine borers are met with. An example of a platform wall built at some distance from the shore is that built at Gowanus Bay, Brooklyn, N. Y., and shown in Fig. 31. A hard sand, clay, and gravel bottom was found at 17 feet below low water, over- laid with mud 12 or 15 feet deep. Marine borers were absent and there was no objection to the use of untreated piles below half tide. A trench was excavated to a depth of 17 feet, for a distance of 25 feet in rear of the face of the wall, with a natural slope on the inshore side. The slips between the piers, which are to be built in front of this wall, were dredged to 35 feet depth and a berm 50 feet wide at the bottom was left in front of the wall opposite the slips. The piles were then driven and capped and the riprap deposited. After some time had elapsed to allow for settlement the riprap was brought up to the under side of the platform, the deck laid, and the concrete wall built. The area back of the wall was then filled with selected sand and gravel pumped from the slips. Some difficulty was caused by the filling washing through the riprap at its 78 WHARVES AND PIERS junction with the platform, where the thickness of riprap, through which the filling passed, was a minimum. This could have been prevented by careful grading of the riprap to make it sufficiently tight to hold the filling, by depositing a bed of selected dry filling over the riprap, or by placing a vertical sheeting at the rear edge of the platform. It is important to make the dredged trench of sufficient //?'- n ,; /- _r / f e/e/y tfWrt-*** /" J ! ! ^/^^ ^^ f ^^ Fender,.... m Anchor Rod Fig. 50. Wall of Wooden Sheet Piling with Concrete Platform, Municipal Pier, Chicago, 111. and concrete walls affected the appearance only and not the safety of the structure. The boring of -the horizontal holes in the piles 2| feet below the surface of the water where the waves were often high and troublesome and the placing of the rods in the holes were accomplished by an ingenious device. Augers, driven by means of pneumatic boring machines, were RETAINING WALLS 97 El. ZSI.O mounted in guides in a wooden frame which was sus- pended from guide timbers. The boring machines were arranged so that when the guide frame was in place they were above the water and were connected to the augers by inclined shafts and universal joints. The tie rods were placed by men clad in watertight rubber suits standing on a sub- merged raft. A design somewhat similar to the foregoing, e/rce/yect hot in which steel-sheet pil- ing instead of wood is used, is illustrated in Fig. 51. In this case the relieving platform is only about 8 feet wide for 16 feet depth of water and the principal portion of the thrust is taken by the tie rods and anchor piles. The small area of the steel beam in rear of these anchor piles and the absence of bracing piles in the anchorage is noticeable. Another design for a coal-loading wharf at Toledo, O., in which bracing piles are used to take some of the thrust, is shown in Fig. 52. This wall was built outside of an old one and the work was done in the winter when navigation was closed. A relieving platform wall of reinforced concrete for an ore dock at Detroit, Mich., is illustrated in Fig. 53. The filling is retained by a low sheet-pile bulkhead behind a reinforced concrete platform 36 feet wide on oak piles, over the natural sloping bank of the river, without riprap or other revetment. The depth of water at the edge of the deck was about 15 feet. The platform, not being intended /2'Chan 2 Die, Tit Rod Spacing 10-0 "c. foe 98 WHARVES AND PIERS for the landing of freight, was designed for a load of only 100 pounds per square foot. The heavy, longitudinal girders carry tracks for an ore unloading machine, the main tower of which spans the platform. The relieving platform carries a railroad track and the ore floor, the portion under the latter being designed to carry 6800 pounds per square foot. The piles were cut off 3 inches above the water line and the concrete girders extend 6 inches below it. The fendering system consists of a line of spring piles and an oak fender on the outer edge of the platform slab. Patents on the general feature 3 of this Blocks, so' c. toe. Key.at Expansbn '~'~te, every SO' Elevation Fig. 52. Wall with Wooden Sheet Piles and Concrete Platform, Toledo, O. wall are held by S. D. Carey, Cleveland, O. A somewhat similar wall, constructed at Cleveland under the same patents is shown in Fig. 54. Another wall of similar type for an ore dock at Cleveland, is shown in Fig. 55. The piles under the wall, except those in the front and rear rows, were cut off at mean low water. The anchorage consisted of old rails which, together with the tie rods, were entirely buried in concrete to prevent any possible corrosion. Oak piles were used throughout. This wall had to support heavy heaps of ore immediately in the rear of the platform. A novel method of capping piles, cut off below low-water level, was used at Hamilton, Ont., on a wall built with a narrow relieving platform supported by transverse, braced RETAINING WALLS 99 100 WHARVES AND PIERS pile bents, which also afford lateral support to sheet piling, as illustrated in Fig. 56. This wall was built out in the water at some distance from the natural shore line. The work of capping and Fig. 54. Platform Wall, Cleveland, O. bracing the piles is usu- ally performed by divers and is slow and expen- sive, particularly where the water is rendered turbid by sewage or other causes. In this case a floating caisson or diving bell was used to cap the piles, which were driven down some two feet below low lake level and cut off at three feet below that elevation. The water was depressed to a depth of about 6 feet, and the air pressure was therefore Fig. 55. Platform Wall with Wooden Sheet Piling, Cleveland, O. only about 3 pounds per square inch. The longitudinal alignment of the piles was effected by timber clamps, placed below the caps and tightened by wire ropes, operated by a hoisting engine, as shown in the illustra- RETAINING WALLS 101 tions. Steel-sheet piling at the face of the wall was used to retain the filling. An interesting comparison could be made between this design and one in which the horizontal thrust is taken by bracing piles instead of by the plank braces put in place by divers. A design for a relieving platform wall at Jacksonville, Fla., with a vertical facing of steel-sheet piling is illustrated in ~-ftjl!ey^ - PjJ '-Pile alignment Hois t clamp timbers Lackawanna steel Ready for Work Dredged-, E/.227.S Y- >,-lk"diam.botf,3 ! 6"la.. .Finished Pile Benf V Pitetenf at I I ft. "centers 3C - 3'J<- 3' J, . 3 !j < ..r/ (6 ?.. J SECTION THROUGH FINISHED WALL SHOWING (DOTTED) LONGITUDINAL SECTION OF CAISSON Plan Fig. 56. Method of Capping Piles for Platforms, Hamilton, Ont. Figs. 57 and 58. The sheet piling is supported by I beams driven into the shell rock of the bottom and is protected from corrosion by concrete deposited by means of a tremie. The I beams are spaced 4 feet apart and are tied at low- water level to inclined pile anchors located 39 feet in rear of the face of the bulkhead. The timber relieving platform is 18 feet wide and is designed to carry a live load of only 200 pounds per square foot in addition to the weight of the filling. This platform reduces the thrust on the sheet 10.2 WHA&VES AND PIERS piles and tie rods to the sum of that of the filling above the platform and that of the pressure wedge below the platform, Fig. 57. Platform Wall, Jacksonville, Fla. E e S+ee/ Sheef ft/ing Fig. 58. Horizontal Section of Fig. 57. which is diminished by the resistance of the platform piles. This wall is planned for a depth of water of 30 feet below mean low tide and a height of only 4 feet above it. EETAINING WALLS 103 SHEET-PILE WALLS Sheet-pile walls, for purposes of classification, may be defined as those in which the material behind the wall is retained by a row of sheet piling, supported against the pressure of the filling by the resistance of the material into which the piles are driven, and by tie rods running back to anchors of various patterns embedded in the earth in the rear, or by bracing piles in front. Those in which sheet piling is used in conjunction with a platform have been classified as platform walls. The great advantage of sheet- pile walls lies in their cheapness, simplicity, and the ease and rapidity with which they may be constructed. Those that are of timber decay above water in a few years and then have to be torn out and rebuilt or repaired by driving another row of sheet piling outside the old one. In many cases the latter method is impossible, owing to the restric- tions of the harbor authorities, property lines, and to the undesir ability of narrowing slips and waterways. Because of its lack of durability and the cost of rebuilding, the use of wooden sheet-pile walls for important structures has of late years been abandoned in favor of those of concrete or steel, or of those in which a relieving platform is used. The use of unprotected steel-sheet piling in fresh water has increased greatly in the last few years. Sheet-pile walls are especially suited to places where it is necessary to build a wall close to existing structures. The reliability of this type of wall depends largely on the nature of the support for the upper portion of the piling. For this purpose nothing can compare with bracing piles, and anchors for tie rods of which bracing piles do not form a part are, in many cases, most objectionable on account of the uncertainty of the horizontal compressibility of the material in which they are placed or of its safe angle of repose. One of the simplest forms of wooden sheet-pile bulkhead was used for many years in Chicago and is shown in Fig. 104 WHARVES AND PIERS 59. A row of round piles was driven along the bulkhead line, a mud sill and two or more wales placed in the rear of these, and sheet piling driven against the sills and wales. The round piles were tied with rods to deadmen in the rear of the wall. For temporary structures, requiring no very great depth of water, in the firm, tenacious clay of the Chicago district, this design is sufficiently good. It is also exceedingly cheap. A simple form of steel-sheet pile wall was used for the EL3&M [] El. -1-2.0 El. 00 1. -10. Fig. 59. Sheet-pile Wall, Chicago, 111. approach to the ship lock at Blackrock, Buffalo, N. Y., and is shown in Fig. 60. In this case the required depth of water was 23 feet. A row of painted, interlocking steel- sheet piling of the arched form, which gives a very high bending moment, was driven 10 feet below the bottom of the canal and tied back to a pile and wooden beam anchor- age, with rods placed some 2 feet above mean lake level but above the water surface at the time they were placed. Two lines of wooden wales or fender timbers completed the structure. This wall acts simply as a retaining wall on RETAINING WALLS 105 the approach to a canal lock, and does not have to carry any great surcharge of freight or other live load. Bracing piles were not used in the anchorage. A steel-sheet pile wall, founded on rock, was built for a coal pier for the Pennsylvania lines at Sandusky, Ohio. The sheet piling is supported by reinforced concrete piles spaced 8 feet, 9 inches, apart, dowelled to the rock with old car axles. The concrete piles and the steel-sheet piles are embedded in the bottom of a light, concrete gravity wall, 8 feet high, extending one foot below mean lake level. At the middle of the panel between the ^tg^^ ., . 4^ */, kv/ concrete piles, pairs of 2-inch rods are attached to the heads of the steel-sheet piling with washers made of old rails and are fastened, at the opposite side of the pier, to an old dock wall. The rods are encased in concrete E/.-33.O Fig. 60. Steel-sheet Pile Wall, Black Rock, Buffalo, N. Y. to prevent any possible corrosion. The piles are octagonal in section and 18 inches in diameter. They are reinforced with vertical rods and hooping and have moulded into them the two halves of a split sheet pile and a 6-inch pipe. Through the pipe the hole for the dowel was drilled into the rock after the pile was in place and the car axle then dropped down through the pipe and grouted into the rock. There were 18 feet of water over the rock at this pier. Fig. 61 shows the construction. Another wall of extraordinary height founded on rock, though not strictly a sheet-pile wall because the sheeting is horizontal instead of vertical, was built for the same railroad at Ashtabula Harbor, Ohio, and is shown in Fig. 62. The channel bottom in this case was 23 feet below 106 WHARVES AND PIERS mean low water and the wall had to support one side of a fill about 62 feet wide, carrying four standard tracks for heavy coal cars, at an elevation of 17 feet above mean lake level. The posts in this case were made of two 18-inch I beams, spaced 7J feet apart, extending into the rock 4 feet and tied to concrete deadmen at the opposite side of the high fill with 2J-inch rods. Horizontal sheeting of 6-inch by 12-inch lumber was placed behind the posts, from the rock to 18 inches below mean lake level and above the Anchor f?oc/3,- - encased in Concrefa Fig. 61. Steel-sheet Pile Wall, Sandusky, O. wooden sheeting reinforced concrete slabs 6 inches thick, cast in place, were used. At the bottom of the wooden sheeting bags of mortar were placed to make a seal to prevent the filling from washing out. The holes for the posts were 24 inches in diameter and were drilled with a large steam drill with a special form of bit. The space between the posts and the sides of the holes was filled with concrete, which was sent down in bags to divers, who opened the bags and placed the concrete in position. The rock behind this wall extended up nearly to the water line, so that the thrust of the filling was much less RETAINING WALLS 107 than it would have been if the rock behind the wall had been at the same elevation as in front. This design was considered superior to that of an adjacent stO'x/8'W.O. Timber ' ..-Sj* Washers Back to Back Water Line, Cross Section. Side Elevotion. Fig. 62. Wall of Steel Posts with Wooden Sheathing, Ashtabula, O. wall in which vertical sheeting was used, in that it did not require any horizontal wales below the water line, the placing of which was somewhat difficult. 108 WHARVES AND PIERS Another steel-sheet pile wall was built for a terminal or freight warf on the summit level of the Barge Canal at Rome, N. Y. (See Fig. 63.) In this case the portion ex- tending from the top to 2 feet below the normal water level was encased in concrete which was bounded to the sheet piling with steel bars. A continuous anchorage beam of reinforced concrete was provided and the tie rods were encased in concrete to prevent corrosion. The only portion of this wall exposed to rust is the outer face of the sheet piling the heads of the tie rods and the steel wales through which the rods project. These can be ex- amined and painted if neces- sary, as the water can be drawn from the canal in the winter time when navigation is closed. There was a con- siderable saving in the exca- vation in this type of wall over the platform type. The channel in front was excavated after the wall was completed. A reinforced concrete sheet- Fig. 63. Steel-sheet Pile Wall Barge p jl e wa ll illustrated in Fig. Pannl T?nmp N V i 64 has been built to enclose several large solid-filled piers in Baltimore. The previous type of wall consisted of wooden sheet piling with a wooden platform on piles having a stone masonry wall on its outer edge; but the prospect that the teredo, which had been driven from the vicinity by sewage, might return after the construction of a sewage-disposal plant which was under consideration, together with the fact RETAINING WALLS 109 that the type of wall in use required a large amount of dredging, made it appear advisable to build a wall entirely of concrete and steel. Steel cylinders with parallel sides and semicircular ends, 10 feet long, 3 feet wide, and about 29 feet high, were sunk 25 feet apart to a hard gravel bottom approximately 22 feet below low water. The cylinders were tied across the pier to those on the opposite side, or, whenever the distance was too great or buildings interfered, to concrete deadmen. Passing through the cylinders, above the water line, were horizontal steel lattice girders wrapped with wire mesh and encased in concrete. Back of these girders, reinforced concrete sheet piles, 12 inches by 18 inches in section, were driven with their heads bearing against the girders. Another steel girder, encased in concrete, was placed on top of the cylinders at the front edge and supported one side of a reinforced concrete slab, the rear of which rested on a reinforced con- crete wall built on top of the sheet .,. ,-.. , , . ,,, piling. This slab carried a . cobble- stone pavement and on its front edge a concrete curb. The steel cylinders were sunk in a trench, dredged to 15 feet depth, by jetting and driving with a steam hammer mounted in a specially constructed steel frame resting on top of the cylinders. Some of these were put in place without much difficulty, but many obstructions, such as old wooden sheet piling, cast-iron pipes, lumps of brick masonry and logs, were encountered. These had to be removed by divers or by men working from the inside of the cylinders, where it was possible to keep the water down by pumping. The narrowness of the cylinders made such work extremely difficult. The concrete sheet piles were not grooved or dovetailed and were bevelled in one direction to make them drive ?f ; Concrete Sheet- pile Wall, Baltimore, Md. 110 WHARVES AND PIERS close together. They were driven by jetting and steam hammers. It was not always possible, however, to make them fit closely, and in some cases narrow piles were driven in the interstices, and in others additional piles were driven in the rear of the gaps. This wall is said to have cost only $58.00 a linear foot exclusive of dredging and $87.00 inclusive of dredging. ^ 1 1 1 jii i iii i Tie 3 Spaced 20 ~0 "C fo C Fig. 65. Concrete Sheet-pile Wall, Raymond Patent, Barge Canal, Albany, N. Y. A sheet-pile wall entirely of reinforced concrete has been designed and successfully built, in many places, by the Raymond Concrete Pile Co. Some of the features are patented. This wall consists of a line of reinforced concrete sheet piles with their heads supported by a horizontal girder, located above the water line, which rests on a row of concrete bearing piles some three or four feet in front of the sheet piles. The girder carries a vertical facing wall which is held against the overturning forces by buttresses RETAINING WALLS 111 supported on a row of piles in the rear. The whole struc- ture is tied back to concrete deadmen. This design, though expensive in comparison with other types, is efficient where it is absolutely necessary to use concrete for the whole structure, but rather extravagant in the use of concrete for ties and anchor piles. The use of concrete for this purpose is justified, however, in some non- tidal waters where the anchor piles cannot be cut off low enough to ensure their safety from decay. A wall of this type at the Barge Canal Terminal at Albany, N. Y., is shown in Fig. 65. CHAPTER V PIERS COMPARISON OF TYPES OF the three types of piers pile-platform, block-and- bridge, and solid-fill the first is usually the most ad- vantageous in localities where the water is not too deep and the bottom is suitable for piles. It offers less obstruc- tion to the free flow of water, sewage, and ice, does not materially affect the tidal prism, may be rapidly constructed, and may be readily altered, removed, or enlarged. In piers of ordinary proportions of length to breadth, where marine borers are not active, it is usually cheaper than the filled-in type. The block-and-bridge model is rather limited in its applica- tion, as it is economical only for small piers in shallow water and on hard bottom. It has the advantage that if the blocks are of cribwork it may be built without the use of expensive equipment, such as pile drivers and floating derricks. The solid-filled type of pier may be used where the ob- struction to the flow of the water, sewage, and ice and the diminution of the tidal prism are not serious objections. It has been urged that a large vessel lying alongside a pile pier offers nearly as much obstruction to the flow of water as a solid-filled pier, but it is to be remembered that in tidal waters the bottom of the ship is near the bottom of the slip only a portion of the time and that for some portions of the time, parts of the pier are not obstructed by ships, thus permitting the flotsam, ice, etc., which accumulate in a slip to pass away. The disadvantage of PIERS 113 the solid-filled piers, especially where they are built in groups, is, in this respect, real and important. Filled-in piers may have greater stability than pile piers, depending on the nature of the retaining structure, but when so built are liable to do more damage to vessels which may collide with them. The comparative cost of pile and filled-in piers depends on the local conditions and on the ratio of the length to width of the prer, the filled-in type having the advantage where the width is very great. For piers in Brooklyn 1300 to 1800 feet long, the filled-in type with one-story sheds was considered cheaper for widths over 100 feet; and in Philadelphia, for a length of 550 feet, the economical limit for pile piers with two-story sheds was estimated at 200 feet. The comparative durability of a filled-in pier depends on the nature of the retaining structure. If this structure is of the same nature as that of the sides of a pile pier, there is, when decay is the only agent of destruction, very little advantage in favor of the filled-in type, as the interior portion of a carefully designed pile pier is very durable, especially if it is covered with a shed. Where there are borers, how- ever, a solid-filled pier may be surrounded by a cheap non- permanent type of marginal construction affording a smaller area subject to the action of the borers than in an open pile pier. One of the most important objections to the filled-in type is the length of time required for construction and the time required for the filling to settle so as to furnish a stable support for a smooth and level flooring or pavement, which is essential for the economical use of freight-handling trucks, either hand-operated or electrical. The solid-filled pier, however, will ordinarily support a comparatively heavy live load on those portions of the floor not near the edge. Filled-in piers are less combustible than wooden-pile piers in that, even when surrounded by a timber platform, the timber 'forms only a small portion of the structure. 114 WHARVES AND PIERS The filled-in type has a great advantage whenever a large amount of excavated material has to be disposed of, in that it affords an economical method of utilizing such material. This is usually the case, as such piers are generally located where the water is shallower than that required for shipping and dredging is required in the adjacent slips and channels. Filled-in piers are, however, sometimes built in deep water, as at Victoria, B. C., where the depth is 60 feet. PILE-PLATFORM PIERS Classification. The pile-platforrn type of pier may be subdivided into various classes, according to the nature and material of the piles and platform as follows: 1. Wood piles extending up to deck. a. Wood caps and deck. b. Wood caps, concrete decks. c. Concrete caps and deck. 2. Wood piles cut off near low water. a. Earth or cinder fill on platform. b. Reinforced concrete posts or cross walls, con- crete deck. 3. Composite piles of wood and concrete. 4. Metal piles or cylinders. a. Cast-iron piles. b. Wrought-iron or steel piles. c. Wrought-iron or steel cylinders. d. Cast-iron cylinders. 5. Reinforced concrete piles. 6. Reinforced concrete columns. There are other possible combinations of different kinds of piles and platforms, some of which are described in this chapter. Advantages of Different Classes. Wooden piles, un- protected against marine borers, are not suitable, except for temporary structures, in waters in which these animals are present. If a pier is built on creosoted piles it may be PIERS 115 expected that some of the piles will need renewal at the end of 12 or 15 years, and as the worm-eaten portion cannot be replaced without replacing the whole pile, they must be removed and replaced or additional piles driven and pulled under the caps. This requires the removal of a portion of the deck and, if there is a shed on the pier, the removal of a portion of the roof. On the other hand, where borers are absent, the various types in class 1 are suitable and economical, as the portions of the piles subject to decay can be replaced by splicing on new pieces. The prices for materials and other local conditions in New York have caused this class of construction to be used in building the municipal piers in that city. The building of wooden-decked piers has been abandoned as far as possible in favor of those with a reinforced concrete deck, as the wooden deck is the part of the structure which requires the largest amount of repairs and the cost of the concrete deck is very little more than that of wood. This type, however, is not used on deep mud bottom where settlement of the structure is expected. In such locations a thin layer of reinforced concrete is placed on a plank deck and where great settle- ment is anticipated no concrete is used at all. This type of construction is, however, subject to a fire risk from floating oil, cotton bales, etc., which may drift under the pier. In Philadelphia conditions as to borers, tides, shipping, etc., are similar to that in New York and in designing municipal piers the Department of Docks and Ferries obtained bids on six different types of construction in order to obtain a comparison of costs. The bids showed a differ- ence of only 8 cents a square foot, or a little over 3 % between the design similar to that used in New York in which the piles extend up to a reinforced deck and one in which the piles were cut off about three feet above mean low water and supported square concrete posts or columns carrying reinforced concrete beams and deck as in class 26 in the table above, and illustrated in Fig. 76. 116 WHARVES AND PIERS In considering the design of the New York type it was estimated that the tops of all the piles would have to be renewed in 10 or 15 years. This is very different from the New York estimate that only 33| % would have to be renewed every 20 years. As the difference in cost would not pay for splicing the number of piles that it was thought would require renewal within the commercial life of the pier, and as the latter type required no renewals and was free from the fire risk, it was adopted. Another variation of the same general type in which the deck is supported on concrete walls extending from side to side of the pier was also used. It is interesting to note that in spite of the above, recent piers in New York City are being built on a plan similar to that in Fig. 70 with the exception of the addi- tion of side caps. The contract price for these piers is about $1.20 per square foot, including the asphalt pavement, which is less than one half the cost of the Philadelphia piers. It must be remembered, however, in making the comparison, that the New York piers were designed for one-story sheds and those in Philadelphia for two stories with very heavy live loads which required heavier column foundations and more piles. Concrete pile piers have a disadvantage in comparison with those of wood in that it is difficult to brace them transversely. With wood piles it is easy to apply horizontal braces just above mean low water and diagonal braces between them and the caps, thus forming a truss several feet deep. This, so far, has been practically impossible with concrete piles, and they have been braced entirely with inclined piles or by deepening the caps so as to reduce the length of that portion of the piles subject to bending. A difficulty is found in the construction of piers with concrete superstructures, in the support of the forms for the girders, joists and deck, which are often of very long span, and in the removal and transfer of the forms from bent to bent. Steel beams encased in concrete have been used in many cases instead of reinforced concrete for these PIERS 117 118 WHARVES AND PIERS members, as they support themselves as well as the forms for the deck. Piers with Wood Piles Extending up to Deck. While reinforced concrete may be more economical than timber for piers where the estimated life of the structure is taken at fifty or seventy-five years, it usually cannot compare in economy with timber for an estimated life of forty years. For this reason there will always be a demand for good wooden piers whenever lumber of good quality can be Fig. 67. Pier with Wooden Piles and Deck. B. & A. R. R., Boston, Mass. obtained at low prices, as on the Pacific Coast and on the Atlantic since the opening of the Panama Canal. An excellent example of a pier of the class designated in the table as No. la, of a type adapted to general use is that described in Chapter III. This design, after over forty years of experience, has undergone little alteration and is still used where the concrete deck is not desirable. The North German Lloyd Steamship Company's piers, which were built to replace those which were destroyed in the great fire in 1900 are chiefly notable for the vertical sheathing on the outside, extending from the deck to low water and for the layer of concrete on the wooden deck which was added for fire protection. This concrete carried PIERS 119 a wearing surface of plank. A section of these piers is shown in Fig. 66. Piers of this class on the Pacific Coast differ notably from the above in the use of 2-inch by 14-inch joists for supporting the deck instead of 12-inch by 12-inch " rangers." In 1910 the Boston & Albany Railroad constructed several piers at East Boston to replace those destroyed by fire, the main features of which are shown in Figs. 67 and 68. ? "Spruce Wearing Su'foc Section at Column Fig. 68. Portion of Fig. 67 enlarged, showing Column Foundation, Ventilator, Floating Fender and Details of Deck. The larger piers are about 770 feet long and 250 feet wide, and the slips between them were dredged to 35 feet at low water. A part of the central portion of them consists of a natural bank of earth extending up nearly to the elevation of high water. The general construction is of timber with wooden piles. Inclined piles were used freely and the ten- foot range of tide with the deck at 10J feet above mean high water permitted the use of efficient transverse bracing on the vertical piles. In one of the piers the piles are cut off 2 feet above mean low water and capped, the deck being supported on posts resting on the caps, this saving in the 120 WHARVES AND PIERS length of the piles and providing an easy method of replacing a portion of the structure subject to rot. These piers were designed with the purpose of providing cheap, durable, and economical structures. Great attention was paid to fire protection and the prevention of rot. A line of sheet piling was driven all around the earth cores of the piers to protect the sloping banks from erosion. From high water to low water the sides of the piers are sheathed with heavy planking to exclude burning oil and other floating materials. This sheathing is surmounted, between high-water mark and the deck, with vertical, reinforced concrete slabs 4 inches thick. Thorough ventilation is provided in order to prevent as far as possible the decay of the timber. This is accom- plished by openings 2^ feet by 3| feet spaced 9 feet apart in the concrete slabs and by ventilators on the sides of the track pits. A novel feature is the provision of an inspection walk under the deck to facilitate the observation of the condition of the structure, particularly in regard to decay. The decks are of concrete outside the sheds and inside they are of unusual construction, being formed of a layer of 4- inch plank on which are placed two layers of four-ply plaster board, a protecting layer of J inch spruce, and a renewable wearing surface of 2-inch spruce. The details, fastenings, and bracing of these piers were designed with exceptional care and thoroughness. In designing a large State pier for New London, Connec- ticut, shown in Fig. 69, a combination of various types of con- struction was selected. The pier consists of a filled portion 100 feet wide surrounded by a pile platform 50 feet wide. The filled-in portion only is covered by a shed. The pile platform is built of creosoted piles, caps, and bracing, which support a deck of pre-cast reinforced concrete slabs, each 23 feet long and 6 feet wide, weighing about 7 tons. The slabs rest on the pile clamps, but are not fastened to them in order that the structure may not be so rigid as to injure vessels. On the slabs is a 2-inch asphalt wearing surface. PIERS 121 122 WHARVES AND PIERS The shed on the filled-in portion of the pier is to be used as a warehouse and not merely as a pier shed for the tempo- rary storage of cargo in transit between the ship and ware- house. The function of the pile platform is merely that of an unshedded pier with railroad tracks on it. The absence of the necessity for covering the platform with a shed had a decided influence on the design, in that, as the shed does not cover any portion of the platform and as the slabs can be removed at comparatively small expense, any portion of the piles or timber structure may be repaired or renewed without destroying the deck or the roof. The retaining walls for the filling are of riprap surmounted by rubble walls on piles. The method of obtaining a uniform bearing for the masonry on the foundations is interesting. The piles were driven first, and the riprap was put in place around them. Quarry stones were then placed on top of the riprap in such a way as to form a channel on top of each row. This channel was lined with waterproof paper, forming a mould in which was cast a reinforced concrete girder, which conformed to the tops of the piles, no matter how uneven they were either in line or elevation. The design adopted for this pier was based on the in- vestigation of four different types: these were (a) steel cylinders filled with concrete supporting steel beams encased in concrete; (6) concrete piles and deck; (c) wooden piles, with wood deck and concrete sheathing and (d) creosoted piles cut off at mean tide and supporting inverted concrete boxes which formed the deck. The economy of the design was calculated on the assumption that the commercial life of the structure would be only twenty-five years. The total cost for the purposes of making the comparative estimates was considered to consist only of the original cost and the serial sum of the interest on the investment, and the annual average maintenance charge. One of the first of five large piers built with wooden piles, wooden caps, and concrete decks is that at 33d Street, PIERS 123 Brooklyn, N. Y. It is shown in Fig. 70. In this design the wood is reduced to a minimum, even the side caps which in the previous designs of the New York Dock De- partment were placed on the side piles below the cross caps or clamps were omitted. The cross rows of piles, spaced 10 feet apart, were braced and clamped in the usual manner, except for the omission of the side caps and the addition of four rows of longitudinal bracing which were found ^"Distributing Rods /' .^Diam.Tension RocfsY l '^% ' ^- Half Cross- Section at Foundation Row Half Cross Section at Intermediate Row Fig. 70. Pier with Wooden Piles and Reinforced Concrete Deck., 33rd St., Brooklyn, N. Y. necessary to hold the transverse rows of piles straight during the construction of the decks. The illustration shows the method of constructing the concrete deck. The slabs were cast in alternate bays 10 feet wide extending from side to side of the pier. It was intended to have the granolithic finish on the concrete act as the wearing surface, but it did not prove durable and the deck was covered with a IJ-inch asphalt pavement. Provision was * made for carrying sewer boxes to the outer end of the pier, as shown in the illustrations. 124 WHARVES AND PIERS The pier carries a single-story steel shed with four rows of posts. The two outer rows of piles are spaced twelve feet apart and the deck over this portion consists of a concrete slab reinforced with wire mesh, supported on wooden planks resting on rangers built up of two 12-inch by 12-inch timbers placed one on top of the other. Adjacent piers commenced within the last year have the wooden side caps restored, as it was found that their omission allowed lighters to float under the deck of the pier and rip it up when the tide rose or when there was a heavy swell. A freight pier of this type for the Central Railroad of New Jersey at Communipaw is notable in that all the piles and lumber are creosoted to prevent decay and that the presence of rock under the sand and gravel of the bottom allowed a pene- tration of only 8 feet for the piles. To give the structure stability cribs extending from side to side of the pier and covering the space of four rows of piles were placed at the outer end and midway between that point and the bulkhead. In Boston concrete caps and deck on wooden piles were PIERS 125 used in the reconstruction of Commonwealth Pier No. 5, shown in Figs. 71 and 72. This pier was built in 1900 and re- built in 1913, the wooden pile-caps and decks being replaced with concrete beams and slabs. Where a portion of the Section G'H ^"Spacing Kbds-. sfKhMbk T 6 /Jw?/.,g- Section E-F r Spacing "Cross- Section of Platform. Burned Section Fig. 72. Pile Platform with Wooden Piles and Reinforced Concrete Caps and Decks. Commonwealth Pier No. 5, Boston, Mass. platform had been destroyed by fire the concrete beams were 7| feet deep and extended down practically to high water. A feature was the placing of cast-iron extension piles in the beams, so that the latter would be supported in case the lower portion should be disintegrated by frost and sea water. 126 WHARVES AND PIERS Piers with Wooden Piles Cut off near Low Water. The pier on wooden piles with the platform at low-water level with incombustible materials above has the advantage over the type in which the piles extend up to the deck, that no portion of the structure is subject to decay and that it is free from fire risk from cargo on deck, vessels alongside, or from burning oil, cotton bales, or similar articles floating under it. When the platform supports a solid filling held in place by a masonry wall it has the disadvantage that the piles Fig. 73. Pier with Platform at Low Water Level on Wooden Piles, D. L. & W. R. R., Hoboken, N. J. carry a heavy dead load and many more piles are required than in class 1 or in class 2, where the platform supports a concrete deck on posts. This type is not suitable for waters in which the marine borers are active, even if the piles are creosoted, if a life of more than fifteen or twenty years is desired, as the nature of the structure above the platform renders the renewal of the piles practically impossible when the creosote is washed out and the piles are eaten away. A pier of class 2a, 100 feet wide and 600 feet long, is shown in Fig. 73. In this case the pier was built by a railroad which had close at hand a large supply of cinders, PIERS 127 which afforded a cheap and light material for filling. The mud at this location was 185 feet deep and the piles were 85 feet to 95 feet long. They were driven 3 feet apart in transverse rows 5 feet apart and were designed for maximum, loads of 12 tons. The depth of water at the sides of the pier varied from 20 to 30 feet. Another pier near by has a portion of the piles in hard bottom and a portion entirely in mud. In this case the loading is varied from 17 to 12 tons, according to the nature of the bottom. An example of type 2b is that adopted for some piers at the U. S. Navy Yard in Brooklyn, Fig. 74. In this case Pit Vpes l*T"/f J 1 Wood Block P -.,. Cable&Elec. )f?.R.Track: Pavement? t< ' /P /f! Tracks Due h . Columns ore precast in units and keyed fa 6 the cross octps. 2-0'- Fig. 74. Pier with Timber Piles supporting Reinforced Concrete Deck on Reinforced Concrete Posts, Navy Yard, Brooklyn, N. Y. reinforced concrete columns with spreading tops were cast on shore and fastened to a timber platform on piles, located just above low water, by keys and wedges. A reinforced concrete deck was then laid on top of the columns. This method avoided all the uncertainties of concrete deposited in forms below high- water mark and subject to the action of the water before hardening, did not put a very heavy unit load on the supporting piles, and gained all the ad- vantages of the low, platform type. Some criticism has been made, however, of the possible plane of weakness between the platform and the concrete structure which it supports. In Philadelphia two piers, each 550 feet long and 180 128 WHARVES AND PIERS feet wide, with wooden piles cut off just above low water ^ ^ and with concrete above have re- ^!i ^ cently been built. One has cross if\*i> **J| o3 walls of concrete supported on a: ^ double rows of piles 20 feet apart o3 - , := 3 an d one has columns on groups of ^ piles spaced 20 feet in each direction. g The tidal range is about 6 feet and g the concrete walls and columns were 1 cast between tides. The two sec- ^ tions are shown in Fig. 75. These designs were selected from six on 1 which bids were received. The A . T5 other designs were for pile platform * types 2a and Ib and solid-filled piers. The second of the chosen designs was the cheaper, but it was 2 desired to give both a trial, as a (!) O O 'S === ^ number of similar piers was to be built. Piers on Composite Piles of Wood and Concrete. Two large steamship piers have been built in the tropics on wooden piles pro- g tected with concrete, one at Bocas del Toro, Panama, and one at Port au Prince, Haiti. The pier at Bocas del Toro is o shown in Fig. 77. 1 It was built ^ parallel to the shore on a shelving g bottom, where the water was 10 feet | deep on one edge of the structure and 22 feet on the outshore side, o The tidal range was only 9 inches be and the locality was free from k ocean swells. Untreated wo'oden 1 T. H. Barnes " The Reinforced Concrete Wharf of the United Fruit Com- pany at Bocas del Toro, Panama." Trans. Am. Soc. C. E., Vol. LXXI, p. 295. r- F PIERS 129 piles were driven ten feet apart in both directions, with an average penetration of 40 feet, and over them were placed, by a floating pile-driver, tapering, conical, reinforced concrete shells, extending from below the mud 130 WHARVES AND PIERS line to above high water. These shells are 2 inches thick, 20 inches in diameter inside at the top, and 16 inches at the bottom. The space between the pile and the shell was sealed with concrete deposited through the water, the water pumped out, and the remaining space filled with lean concrete to within 5 feet of the top of the shell. Reinforce- ment for the columns which extended from the tops of the shells to the pile caps was then put in place, the shells Fig. 77. Pier with Composite Piles and Reinforced Concrete Deck, Bocas Del Roro, Panama. filled to the tops, and the whole protected pile straightened and stay-lathed. Forms supported by steel rails which rested on the tops of the shells were then built for the reinforced concrete columns, beams, braces and slabs, and the concrete portion of the structure completed. One of the most difficult points in the design of nearly all concrete piers is the transverse bracing, and a notable feature of this pier is the use of horizontal and diagonal braces of reinforced concrete. These were successfully constructed, though with some difficulty. The horizontal PIERS 131 braces were placed at about mean high water and the diagonals had a rise of about 4J feet, the deck being about 8J feet above mean tide. The shells were reinforced with electrically welded wire fabric with a 6-inch square mesh. They were from 16 to 30 feet long and were made at the rate of about six in a day. It was estimated that the pier cost about as much as one built of creosoted piles with creosoted timber beams and deck, but that it would last much longer, as the life of such piles was considered to be only 15 years. Various designs for concrete piles were considered, but were discarded, as Port Section A-A Port Section B-B Fig. 78. Pier with Composite Piles and Reinforced Concrete Deck, Port au Prince, Haiti. the length of 70 feet, which was required, was unprecedented in 1906, when this pier was built. Only a small plant was required consisting of a floating pile-driver in addition to the stone crusher and concrete mixer. The slab is 7 inches thick and calculated for 250 pounds live load. Test piles were driven and loaded to determine the bearing power. A pier of similar construction was completed at San Francisco in 1913. It was 800 feet long and 126 feet wide. The pile caps were of steel encased in concrete and carried wooden stringers and a plank deck. A pier at Port au Prince, Haiti, was built in 1912 on timber piles protected by encasing them, before driving, 132 WHARVES AND PIERS with wire mesh and cement mortar. The pier is 825 feet long and from 50 to 60 feet wide, and is located in water with a minimum depth of 27 feet. The design is shown in Fig. 78 and the method of constructing the pile in Fig. 79. The piles had a maximum length of 57 feet and the penetration varied from 15 to 30 feet. The protective coating on the piles reached from the tops to within 5 feet of the points. They were spaced 10 feet apart each way, and were capped with reinforced concrete girders 18 inches wide and 5 feet 6 inches deep, arched between the piles, supporting longitudinal beams and a 5 to 7 inch slab. The Fig. 79. Composite Pile, Port au Prince, Haiti. forms for the superstructure were supported by means of wooden collars clamped to the piles. Piles of somewhat similar construction, in which the mortar was applied by the cement gun, were used in con- structing a bulkhead wall at San Juan, Porto Rico, in 1913. These piles were driven to a 20-ton bearing with a 3000- pound drop hammer without damage to the protective coating. Piers on Metal Piles or Cylinders. Before the advent of reinforced concrete, piers on piles or large cylinders of cast iron, wrought iron, or steel were built in many places where marine borers were active. Some have withstood corrosion very well and have lasted for 30 years or more and some, notably those built on piles made of steel pipes, PIERS 133 for steamboat landings on the ocean shore, have lasted only 10 years before they needed extensive repairs. One of the earlier piers of this design was built at Fortress Monroe, Va., thirty-two years ago. This pier was designed for a steamboat landing and is in a location exposed to strong winds and currents and at times a heavy sea. The piles were of cast iron, one inch thick, and where there was a firm bottom, had a disc on the lower end and were jetted into place. In a portion of the pier where there was a layer of mud overlaid with sand, creosoted wooden piles were first driven and cut off above the bottom; cast-iron screw piles were then forced down over them. All the iron piles were pumped out and filled with concrete. A platform of creosoted piles with wooden deck was built around the por- tion of the pier at which the steamboats landed, as the iron structure was thought to be too lacking in elasticity for boats to lie alongside it. Recent reports state that the cast- iron piles are in as good condition as when put in place, but that the beams of the deck are badly corroded, the scale being J inch or more in thickness. An iron coal pier was built at Lamberts Point, Norfolk, Va., in 1892 which carried an elevated steel railroad struc- ture for loading coal. The piles were of commercial tubing 12 inches in diameter and J inch thick, 45 to 57 feet long, and were filled with concrete. They were fitted with discs 4 feet in diameter and were jetted into place in a sand bottom. The jetting was aided by pulling down on the piles and each pile was weighted to bring it to a firm bearing. The iron piles were surrounded by a braced fendering of creosoted piles. Iron cross bracing, extending considerably below the low-water line, was used to give lateral strength. An ocean pier for a steamboat landing was built in 1879 at Coney Island, N. Y., of wrought iron tubular piles about 57 feet long and 8f inches in the outside diameter and \ inch thick. They were fitted with cast-iron discs and were sunk from 12 to 15 feet into a sand bottom. This pier had two decks 12 and 24 feet above high water and the piles 134 WHARVES AND PIERS were cross braced between the water and the lower deck. Another pier of somewhat similar construction was built at the same place several years later. Another example of a tubular steel pile pier is that built in the open ocean for a steamboat landing at Atlantic City, N. J., in 1897-1898. The piles were 10f inches in outside diameter and f of an inch thick and the caps were of plate- girder construction. In 1905 the piles and particularly the girders had rusted so that they were reduced in section by from to ^. The pier was entirely rebuilt by encasing the piles and beams in reinforced concrete designed to take the entire load independent of the remaining strength of the original structure. Another similar pier was built at Old Orchard Beach, Me. Many piers have been built with iron or steel cylindrical columns filled with concrete, both plain and reinforced. A wharf of this type was built at Tampico, Mexico, in 1900, for the shipment of petroleum, to replace one of creosoted timber which had been burned to the water line. The bottom at the site of the wharf was formed of fine sand about 50 feet below the water level overlaid with silt. The cylinders were about 50 feet long and 6 feet in diameter of ^-inch steel plate, except the portions above water, which were f inches thick. Most of the cylinders were sunk by pulling down with jacks attached to the old piles and by driving with a light hammer, but some were sunk by the pneumatic process. Piles were driven inside the cylinders by means of a 30-foot follower, and extended into the sand. The mud and water were removed from the cylinder and they were filled with concrete, the portion required for sealing being placed by means of a tremie. They were spaced about 20 feet apart each way and were calculated to carry from 116 to 235 tons each. The deck was of steel beams supporting a concrete arched flooring designed for a live load of 800 pounds per square foot. The two upper sections of some of the cylinders were gal- vanized and the piles were creosoted. The purpose of PIERS 135 creosoting the piles, which were entirely protected by the concrete, silt, and water from rot and borers is not apparent. The design is well shown in Fig. 80. Fig. 80. Wharf with Steel Cylinders, Tampico, Mexico. Two piers of similar construction, one of which was 70 feet wide and 600 feet long, were built in Manila in 1906. The columns were spaced 20 by 25 feet. They rest on clusters of piles cut off at various heights. The steel shells were placed over the piles, the mud and water pumped out, 136 WHARVES AND PIERS the bottom sealed with concrete, reinforcement placed, and the shells filled with concrete. The columns were capped with plate girders carrying steel beams and a reinforced con- crete slab with a wood block pavement at 10 feet 5 inches above mean low water. The steel cylinders were very thin in these piers and the concrete which filled them was heavily reinforced. Such cylinders act merely as forms for the concrete above the bottom, as they soon rust away. The cylinders were braced with diagonal rods of steel. Another huge coal pier was recently completed at Lam- berts Point, Norfolk, Va., in which the steel superstructure which carried the railroad tracks was supported on steel cylinders 41 feet high and 18 feet in diameter filled with concrete resting on piles which were driven by means of a follower and telescopic leads to 27 feet below low water. The concrete was not reinforced. A protective structure of timber with creosoted piling was built around the cylinders to provide wharfage for vessels. A pier with cast-iron cylinders 30 inches in diameter and If inches thick was built at Cienfuegos, Cuba, in 1906. The cylinders weighed 420 pounds per linear foot and carried a load of 50 tons each. They were braced with 2-inch square steel rods. The deck beams were steel-plate girders and the deck was of reinforced concrete. One of the first ventures in the use of reinforced concrete piles for large steamship piers is found in those built by the Atlantic and Birmingham Railway at Brunswick, Ga., which were completed in 1907. Two piers were built 140 feet wide, one 350 and one 750 feet long, and the method of construction is shown in Fig. 81. The superstructure was entirely of wood. The piles are rectangular, 10 inches by 16 inches in section and from 32 to 50 feet long, and were driven by jetting through a centrally located pipe. The deck of the pier is 7 feet above high water and 14 feet above low water. The piles were capped with double timbers resting one on each side on shoulders in the piles. The caps carry 6-inch by 14-inch wooden joists notched down on PIERS them and fastened with drift bolts, and a 3-inch plank deck was laid on the joists. Horizontal braces of creosoted 6-inch by 10-inch lumber were bolted to the piles just above low water and four rows of inclined braces were placed be- tween the horizontal braces and the caps. In order to make the sides of the piers elastic, so as not to injure vessels lying alongside, the outside row of bearing piles on each side was of creosoted timber braced with in- clined piles and protected by fender piles of the same material. The pier sheds did not project be- yond the concrete piles, so that the wooden piles could be renewed with- out making holes in the roof of the shed. One of these piers was rammed by a steamer during the construction, without serious damage to the structure. A similar pier was built at the U. S. Navy Yard at Charleston, S. C. In reconstructing the steel pier on the ocean 138 WHARVES AND PIERS shore at Atlantic City in 1906 additions were made with re- inforced concrete piles. A portion of them were of 12 inches diameter with a maximum length of 32 feet 6 inches, driven 8 to 14 feet into the sand, and part were 25 inches in diam- eter with a maximum length of 52 feet and a penetration of 16 feet. The 12-inch piles were cast on end complete with knee braces at the upper end. The 25-inch piles had the lower 12-feet first cast in one piece. A watertight form of galvanized steel or of wood, long enough to reach above the water when the pile was in place, was then attached to the 12-foot section, which with the concrete form was then jetted down to the required depth and the form filled with concrete. Both the steel and wooden forms were left on the piles. The piles had enlarged bulbs on the lower ends, 30 inches and 42 inches in diameter respectively, to give additional bearing power. The original steel piles were encased in a reinforced con- crete jacket with a wooden outer form and a sheet-steel inner form. These jackets were cast above water in section of con- venient length, as they were sunk by water jets to the discs at the lower end of the steel piles. The space between the concrete jacket and the steel pile was filled with concrete. The details of the 25-inch new piles are shown in Fig. 82. A pier in which piles of somewhat similar construction were used was built to serve as a recreation pier and to carry a sewer outfall pipe at Santa Monica, Cal., in 1908. It was 1600 feet long and 35 feet 8 inches wide, 24 feet above mean low water, and the depth of water at the outer end was 25 feet. There were three piles in a bent and the bents were 20 feet apart. The piles were 14, 18, and 23 inches in diameter and had a 30-inch bulb at the lower end. They were about 70 feet long at the outer end of the pier. They were driven by the water jet, a pipe being cast for the purpose in the axis of each pile. The 14-inch piles on a portion of this pier were jacketed with a steel cylinder 22 inches in diameter, made of No. 10 plate from 2 feet above high water to 2 feet 6 inches below the ground line, PIERS 139 the space between the jacket and the pile being filled with concrete. The piles in the outer portion of the pier were not jacketed, as it was found that they were covered with a heavy protecting growth of mollusks soon after they were driven. There were three rows of beams of 9-inch by 18- inch reinforced con- crete between the bents to give longi- tudinal stiffness. The pile caps of 9- inch by 30-inch rein- forced concrete car- ried 4-inch by 16-inch by 22-feet fir joists spaced 30 inches apart and stiffened by 2 rows of 2 by 4 bridging in each bent. On the joists were laid 2-inch plank and a 3-inch concrete slab. Another ocean pier was built on rein- forced concret piles at Long Branch, Fig ' 82 ' N. J., in 1912. The piles were hollow, 22 inches square outside, with a circular hole in them 13 inches in diameter. They were from 45 to 68 feet long and were driven into the sand, clay, and gravel bottom about 22 feet by means of four water jets. A 150 H. P. pump was required. The deck of the pier was 22 feet above low water and the outer portion of the pier, which was intended for a landing place for steamboats, was braced with inclined piles. The shell of the hollow piles was of 1 : 1J:3 concrete and the interior portion was filled with a leaner mixture. The hollow section of the piles provided Ocean Pier with Reinforced Concrete Piles, Atlantic City, N. J. 140 WHARVES AND PIERS a convenient means of splicing those which were too short to reach the hard gravel layer to which it was desired to drive them or which could not be economically handled if made of the required length in one piece, rods being placed in the core to strengthen the joint. Piles made with this /^ J ^^^^J ^- ---U Longitudinal Section of t2$30' Girders Elevation of Fenders Cross Section Through Wales Fig. 83. Reinforced Concrete Pile Pier, Oakland, Cal. rich mixture have proved durable in this locality, while those of 1: 2: 4 concrete have been badly abraded by the sand on the beach between high and low water. The caps, joists, and deck of this pier were of reinforced concrete. Another pier, one of the first large piers entirely of con- crete, 295 feet long by 124 feet wide, was built at Oakland, Cal., in 1911 and is illustrated in Fig. 83. The piles were octagonal, 16 inches in their short diameter and from 30 to 50 feet long. Driving the piles with a hammer in PIERS 141 the clay and tightly packed gravel of the bottom fractured the heads and they were put in place by jetting and " churn- ing" or " spudding." Horizontal bracing was provided by putting in three concrete brace walls reaching from the deck to the water, extending about 21 feet each side of the centre line of the pier. The deck system is of reinforced concrete girders and beams supporting a 4-inch reinforced concrete slab with a 2-inch asphalt pavement. Fenders are of the timber and car-spring type and the mooring piles are of timber driven through holes in the deck. All timber was creosoted. Concrete of 1: 1|: 3 mixture was used for the upper five feet of the piles and 1: 2: 4 for the bal- ance. The piles were spaced about 10 feet in each direction. Three notable steamship piers have recently been built on reinforced concrete piles of great length, one at Halifax, N. S., where the climatic conditions are most severe, and two at Havana, where the conditions in a tropical climate and a sheltered harbor are most favorable for the durability of the concrete. In the Halifax pier the piles were placed in rows and carried the deck on the ordinary girder and beam construction, but at Havana they were driven in clusters and the deck slab was carried on shallow beams between rectangular pile caps. At Halifax inclined piles were used throughout the pier to give lateral stiffness, but at Havana bracing piles were used only in the two outer rows of pile clusters, as it was not considered that they would give sufficient stiffness in addition to that afforded by the piles, the weight of the structure with its two-story con- crete shed, and the connections between the piles and caps, to pay for their extra cost. For the construction of the Halifax piers an enormous combined floating pile-driver and derrick was built, but at Havana the piles were placed with a floating derrick and driven by a steam hammer resting on and fastened to the heads of the piles. Piles were chosen for the Havana design instead of the large columns such as are used on the Pacific Coast because they 142 WHARVES AND PIERS were considered the cheaper on account of the length of the columns required. A notable difference between the two designs was that while both piers had to carry two-story sheds, the Halifax pier was calculated to carry, a live load of 1000 pounds on the first floor and 500 on the second and 110 on the roof, and those at Havana, only 250 and 400 pounds respectively, r juZ ru M " '" ; -&' H M^r'zfca>tm/7 ^,^ ! ,j&* j>6'- Fig. 84. Reinforced Concrete Pile Pier, Halifax, N. S. and none on the roof. At both places large yards and considerable plant were necessary for fabricating the piles, handling them in the yard, and transferring them to the piers. The Halifax pier is shown in Fig. 84. This pier is one of four to be built in the inner harbor. It is 693 feet long and 235 feet wide, located in water 60 . to 70 feet deep, on a rock bottom, 61 to 87 feet below the pier floor, overlaid by from 5 to 12 feet of clay and hard pan and with 30 feet of soft mud at the shore, and 5 feet at the outer end. The PIERS 143 mean range of tide is about 6 feet and the height of the deck is 14 feet 2 inches above extreme low water. Special precautions were taken to make the concrete durable under the extreme conditions of service. The alumina in the cement was limited to 6.3%, to reduce the chemical action of the sea water on the cement; the pro- portion for all concrete below high water was made 1: 1J: 3 to resist the absorption of water by the concrete and all concrete surfaces were sheathed from low water to 2 feet above high water with two layers of creosoted 2-inch plank to prevent freezing and erosion by waves, ice, and driftwood. The piles were designed to carry 100 tons, including their own weight in water. They are 24 inches square, 55 t-f- f , i-i to 77 feet long, and weigh from 12 to 23 tons. The bracing piles were cast with a camber to com- pensate for the bending of the piles under their own weight. A 12-ton /2"x8'xli"Creosoted Oak Bearing Pieces, 2'c.toc. 2"in Fig. 85. Side Detail, Halifax Pier. steam pile hammer, especially built for these piers, was used. The piles are spaced 10 feet apart in the bents and the bents are 18 feet apart longitudinally. There are six rows of shed columns and under each column there is a bracing pile and one or two extra vertical piles, making 33 vertical and 6 inched piles in each bent. The upper portion of the piles was cast after the piles were driven. They were capped with girders 36 inches deep, carrying beams 24 inches deep and an 8-inch deck slab. Especial attention was given to transverse stiffness, owing to the great unsupported length of the piles. The vertical piles were stiffened by a bank of dredged material deposited around them and by the inclined piles. The Havana piers are 164 feet wide and 660 and 680 144 WHARVES AND PIERS feet long and are located in water from 12 to 40 feet deep, on a bottom consisting of 15 to 20 feet of soft mud over- lying sand or clay. The range of tide is only 18 inches and the deck was elevated only 5 feet 3 inches above mean low water to have it conform to the level of the marginal street. The two-story concrete sheds are carried on columns spaced about 20 by 30 feet apart. The extraordinarily low elevation of the deck required for these piers presented peculiar difficulties in the design, and the problem was solved by supporting the deck slab b^-U44 ^Tm ^*3? Part Transverse Section p ar f Longitudinal Section Fig. 86. Reinforced Concrete Pile Piers, Havana, Cuba. on wide shallow beams carried on clusters of piles located under the shed columns. The clusters contained from four to eighteen piles and were capped with reinforced concrete 3^ feet thick, including the thickness of the slab. The caps measured from 7 by 8J feet to 20 by 24 feet in area. The longitudinal beams were 15 and 18 inches thick and 11 feet wide supported on recesses in the sides of the caps and the transverse beams were cantilevers 7 feet wide. The deck slab averaged 12 inches in thickness. Fig. 86 shows typical pile clusters and sections. In Havana Harbor there is little or no current and the close spacing of the piles and pile clusters was unobjectionable. The piles were 16, 18, and 20 inches square and from 45 to 85 feet in length, with a maximum weight of 17 tons. A notable PIERS 145 feature was that they were reinforced for bending stresses in one plane only, in order to reduce the amount of steel to a minimum. Pipes were cast in the concrete at the proper places for attaching the lifting ropes, and the piles were kept with the proper side uppermost until they were raised to the vertical position. Driving the piles with a water jet proved unsuccessful and they were driven with a six-ton steam hammer at the rate of about ten in a day. Fifteen tons dead load and 25 tons live load were allowed on a pile and the bearing power was determined by loading numerous test piles. Another large pier on concrete piles in San Francisco was begun in 1914. It is 975 feet long on one side and 817 on the other and 200 feet wide. The depth of water is from 41 to 57 feet. The most notable feature of this pier is the extraordinary length of the piles, which have a maximum of 106 feet in the outer rows. They are 16, 18, and 20 inches square and were designed for a load of 40 tons in addition to their own weight. The penetration was about 35 feet, ten of which was in soft material. Piers on Reinforced Concrete Columns. -- The columns in use on the Pacific Coast have been developed to the present successful form through several stages. The design grew partly from a method of protecting wooden piles which was considerably used, and partly from the steel cylinders filled with concrete previously described. The method of pile protection consisted of placing a wood-stave pipe around a pile after it had been driven and filling the space between the pile and the pipe with concrete. The concrete deposited in this manner in many cases, often due to depositing the concrete in water, was imperfect and allowed the teredo to get at the piles, but where the forms were carefully pumped out and the concrete reinforced, success was obtained. In some cases such protected piles failed because the mud line was lowered below the bottom of the casing by dredging subsequent to the completion of the structure. 146 WHARVES AND PIERS The first step was to use a wood-stave cylinder of about 3^ feet in diameter. As it was found that a column of a diameter sufficient to carry the vertical load did not have sufficient area to give the required bearing on the bottom, the foot of the pile or column was enlarged to 7 or 8 feet in diameter. The method of construction was as follows: a wood-stave pipe with a cast-iron bell bolted to the lower end was jetted and hammered down through the mud into the hard bottom. The water, mud, and sand were then removed from the interior, the bottom sealed with concrete, the reinforcement placed, and the cylinder filled to the top with concrete. The wooden form was left in place. A pier in which the concrete for the columns was deposited through the water was destroyed, owing to the disintegration of the imperfect concrete. The next step in the development was by the use of open, cylindrical steel cofferdams in which the columns were built. Some of these were 1\ feet in diameter and 60 feet long, weighing about 20 tons. They were driven by floating pile-drivers, or land leads of enormous size and strength supported on temporary pile trestles. These ma- chines were used to operate the bucket for excavating the sand and mud from the cylinders and for pulling up the cylinders after the columns were cast, also for operating swinging leads which were lowered into the cylinders for driving wooden foundation piles, which were necessary where the bottom did not have sufficient supporting power without them. The cylinders were pumped out and the wooden forms built in them. The concrete was deposited by means of chutes, and was tamped into place by a man inside the forms. The steel cylinders were then withdrawn, the forms being left in place on the concrete columns. Some difficulty was found in keeping these cylinders plumb if the mud for any cause moved while they were in place, and the concrete columns had to be braced to neighboring columns as soon as the steel cylinders were removed. In some cases it has been found impossible from various PIERS 147 causes to seal the steel cylinder. This difficulty was over- come by putting a wooden bottom in the form and suspend- ing it above the water in the pile-driver leads, hoisting the concrete to the top of the form and lowering the completed column down through the steel cylinder. In another case the bottom of the steel cylinder was made detachable, filled with concrete to make a seal, and left in place when the upper portion of the cylinder was raised. In comparing the pier built on concrete piles with that built on columns, the advantage of one over the other, aside from the cost, which may be favorable to either plan, depending on the local conditions, is in the matter of brac- ing. The columns cannot conveniently be braced against horizontal forces except by shallow knees between the heads of the columns and the deck beams, or by steel braces fixed to collars fastened to the columns, which are subject to conditions which produce a maximum amount of corro- sion. Such piers depend on their weight, the stiffness of the columns, and the shallow knee braces to resist the thrust. On the other hand, where the concrete piles are used bracing piles can be driven and the direct resistance of the bottom utilized. Both these types require floating derricks of large capacity, or huge pile-drivers, or both, for handling the piles or the steel cylinders in which the columns are built. While the column method has been used in building several large piers in San Francisco, it is doubtful if it is as economical as concrete piles where the nature of the bottom is such that piles can be driven. Three great piers have been built during the last five years on the Atlantic, one at Halifax on rock at great depth and two at Havana on soft bottom, and the latest pier designed for San Francisco is now being built on concrete piles some of which are of unprecedented length. An early example of the type of pier built on concrete columns is shown in Fig. 87. Two piers Nos. 38 and 40 were built on this plan. In these piers the concrete columns 148 WHARVES AND PIERS were cast in a wooden form with an enlarged cast-iron bottom section, driven by jets and hammered into the impervious clay overlying the rock, and pumped out before the concrete was put in. The depth of the clay was about 40 feet below the water. These piers were about 130 feet by 650 feet and the cylinders were spaced 15 feet each way. The columns carried steel cross-girders and longitudinal Cylfnder Reinforcement 643-3 jjfo End of Pier 629-J%"foC.L.ofLasfCo/. *o* , Outer End I KooT Framing Floor Framiny Plan Fig. 87. Pier on Reinforced Concrete Columns, San Francisco, Cal. beams encased in concrete which supported a reinforced concrete slab and asphalt and brick pavements. They carried single-story sheds built with steel frames and con- crete walls and roofs. Later piers were constructed with columns built in steel cofferdams similar to those at Ft. Mason, and the caps and joists were of reinforced concrete instead of steel. A floating pile-driver with 118-foot leads was used, also one 90 feet high supported on falsework. PIERS 149 The three piers at Ft. Mason, in the construction of which cylindrical steel cofferdams referred to above were first used, are 500 feet long and 81, 118, and 81 feet wide. They are in a locality where heavy ground swells, swift currents, and strong winds rendered the use of floating equipment impracticable and made the work especially difficult and costly. The water was 25 feet deep at the outer end of the pier and the depth provided alongside was 31 feet. The bottom consisted of layers of sand and mud to a depth of from 70 to 90 feet. The columns were spaced 18 J feet each way and were capped with steel beams encased in concrete carrying a reinforced concrete slab supported on beams similar to the pile caps. The columns were 4 feet in diameter above the bell at the bottom and were cast in wooden forms which were built in open steel cylindrical cofferdams. The latter were placed and removed by means of very large pile-driver leads 86 feet high, supported on a temporary pile falsework. Each column rested on 7 timber piles 60 to 85 feet long driven from 20 to 70 feet below the dredging line, and cut off about 11 feet above it. They were driven by means of a follower in a steel guide tube 40 feet long which was accurately located by means of a template and removed after the pile was driven. The steel cofferdams were used after attempts to place the forms without them had been found very difficult. They were 8 feet in diameter and weighed 17 tons. The pile-drivers had a lifting capacity of 100 tons to provide the necessary power for pulling the cofferdams out of the mud. The concrete in the columns was mixed in the proportion of l:lf:3. A pier was built on similar principles to those of the two preceding examples at the Navy Yard at Charleston, S. C., in 1915 in which was introduced a novel feature which permitted the inspection of the concrete in the columns. The lower portion of the steel cofferdam 5 feet long was fastened to the upper portion by means of bolts. The enlarged concrete footing surrounding the wooden piles 150 WHARVES AND PIERS was cast in the steel cylinder as a form. Steel forms for the column were then set on the concrete footing and the column poured. The forms were then stripped, the concrete inspected, and the bolts holding the two parts of the cylinder taken out and the upper portion of the cylinder removed, the necessity of heavy lifting devices for pulling the cylinders out of the mud being thus done away with, a 25-ton float- ing derrick being sufficient. The cofferdam cylinders were from 42 to 52 feet long and 8 feet in diameter. The 45- foot piles were driven with extension leads and a 40-foot follower. Several piers have been built with the decks supported on concrete columns in which thin shells of reinforced concrete, cast on shore, have been used in place of the wooden forms described above. These had the advantage that it was possible to inspect the surface of the concrete exposed to the action of the water and to reject any portion that was imperfect. One of two built at Olongapo, P. I., in 1910 is illustrated in Fig. 88. It is 332 feet long by 45 feet wide and is located parallel with the shore with the outer edge in 25 feet of water. The cylindrical shells are 30 inches in diameter, 2J to 3 inches thick, with an enlarged lower portion to enclose the wooden piles which support them. They are from 25 to 30 feet long. The concrete deck slab was supported on steel girders and beams encased in concrete. The construction of the shells was accomplished without the use of a core-form by using a sheet of wire cloth with 2| meshes to the inch fastened to the inside of the reinforcing hoops. The wire cylinder was then placed inside a wooden exterior mould in a horizontal position. Mortar was then poured into the mould and protruded through the wire cloth just enough to make a key. No interior form was required and a man smoothed the mortar on the inside of the wire with a trowel. The shells were driven from 2 to 4 feet into the sand bottom by water jets, and stay-lathed. A concrete seal was then put in place by bottom dumping PIERS 151 buckets, the shells pumped out, and the interior of the cylinders filled with concrete. These piers were braced transversely with diagonal steel rods placed by divers. A similar pier was built at Puget Sound Navy Yard in 1912. Metal lath of the form known by the trade name of "Hy-rib" was used for the shell of the shaft and ^-inch square wire mesh for the enlarged bottom portion. The Hy-rib was plastered with mortar and the balance of the M.H.W. ML.W itassg*^fl* II tr //*/ Y f i U '] ! 1 1| i .! Fig. 88. Marginal Pier with Reinforced Concrete Columns, Olongapo, P. I. shell was made of very wet mortar poured into the forms. Trenches were dredged for the shells, as the bottom was so full of old piles, boulders, and hard, gravel that the use of the water jet was impracticable. The longest cylinder was 39 feet in length. Diagonal braces of steel rods were used to give transverse strength to the pier, which was only 60 feet wide. No piles were used under the columns. The specification allowed alternate bids on the method of constructing the cylinders in steel cofferdams or wooden shells and the above was chosen in preference to them. 152 WHARVES AND PIERS An interesting method of construction of a pier or wharf on concrete columns is shown in Fig. 89, which illustrates a marginal wharf platform at Iloilo, P. I. In this case the cluster of piles was surrounded with a steel shell drum forced down into the bottom. The earth around the tops of the piles was then removed by a diver and concrete deposited in the drum to within 6 inches of the tops of the piles by means of a canvas bag. The drum was then Section at Lower Horizontal Bars Fig. 89. Wharf Platform on Concrete Columns, Iloilo, P. I. filled to the top with gravel and the concrete columns, which were cast on shore, set up in the gravel. Grout was next forced into the gravel through a one-inch pipe with a funnel on its top. The columns were hollow and when pumped out did not leak and showed that the grouting was perfect. Philipino divers on this work were paid only $1.00 a day. At Balboa, Panama, a concrete marginal wharf, 708 feet long and 55 feet wide, was built in 1911 on large cylindrical, reinforced concrete columns driven to rock at a depth of 60 to 70 feet and spaced 35 by 30 feet. This wharf was PIERS 153 built in a tidal inlet which was cut off by a cofferdam and the construction carried on in the dry. After trying various methods it was decided to cast the cylinders in 6-foot lengths and handle them by means of a locomotive crane. The lower section was 10 feet in outside diameter and the 6,1 Anchor Koc/s Sleeve Nuts anot C.I.Washers Fig. 90. Wharf Platform on Concrete Columns, Balboa, C. Z. upper portion 8 feet, with walls one foot thick. The con- crete in the shells was mixed in the proportion of 1: 2: 4. The vertical reinforcing rods were placed in holes moulded in the shells and rods were connected, at each joint of the latter, by sleeve nuts. The interior of the columns was filled with 1: 3: 5 concrete, reinforced with old rails, after sealing and removing the water. The greater part of the mud and clay was removed by hand excavation, as water 154 WHARVES AND PIERS jets did not work well in the clay, even with 120 pounds' pressure and orange-peel buckets were not as efficient as hand work. The work being performed in the dry per- mitted the placing of heavy transverse and longitudinal reinforced-concrete braces between the columns below low- water level. The mean range of tide is about 13 feet at this location and the bottom along the outside of the wharf was dredged to 40 feet below mean sea level after the wharf was built. BLOCK-AND-BRIDGE PIERS Two masonry piers have been built on the block-and- bridge plan in New York. Pier New No. 1 was begun in 1872 and completed in 1876, and as it was the first pier to be seen from vessels coming from the sea, its design was of a monumental character. It is 453 feet long and 80 feet wide and is formed of 18 semicircular concrete arches of 11 feet, 6 inches radius, 18 inches thick at the crown, sup- ported by cross-walls 5 feet, 6 inches thick, except at the outer end of the pier, where the wall is 12 feet, 6 inches thick. These cross- walls are built of concrete blocks made in air and set by derricks and divers. They rest on beds of concrete deposited by means of buckets in weighted, wooden forms placed on the rock bottom, which is from 25 to 50 feet below the water surface. The sides of the pier are faced, above low tide, with granite about two feet thick. This structure is said to have cost $14.00 a square foot. Pier A was built in 1885, not for commercial purposes, but for the offices of the Department of Docks. The deck is of concrete arches, one foot thick at the crown, supported on longitudinal steel girders resting on cross-walls of concrete blocks, similar to those in Pier 1. The cross-walls are 5 feet, 6 inches thick at the bottom and 4 feet, 9 inches at the top and are spaced 35 feet apart. The cost was about $11.60 a square foot. A small block-and-bridge pier was built near Glen Cove, PIERS 155 N. Y., for a yacht landing. In this case the blocks were hollow, reinforced concrete caissons set in place by large floating derricks and filled with sand. The bridges were of wood. SOLID-FILLED PIERS Solid-filled piers may be divided into two classes. First, those in which there is a pile platform outside of the retain- ing structure, and second, those in which there is no such platform, vessels being moored directly against the vertical or nearly vertical face of the retaining wall. The. former type is usually the cheaper in first cost and most of the large solid-filled freight piers, except the narrow ore piers of the Great Lakes, are of this type. This is due to the fact that such piers are usually built in comparatively shallow water, permitting the use of a wall of relatively small section with the bottom sloping from the wall to the edge of the platform. An example of filled-in piers built with the idea of reducing the first cost to a minimum is that of the Bush Terminal. These piers are located on a sand-and-gravel bottom with a general elevation slightly below low water. The main retaining structure is a line of wooden sheet piling supported by tie rods across the piers and a bank of riprap in front, as shown in Fig. 43. The filling was obtained by dredging the slips. The wharf platform is of the usual New York type of timber construction. These piers were covered with sheds and the flooring over the filled portion was of plank laid on wooden sills resting on the filling. They have lasted from 12 to 15 years without many repairs except where they were damaged by fire. The wooden flooring has been replaced by concrete in some places and some of the piers have recently undergone extensive repairs to the outer portion of the platform. A design for similar piers adjoining those of the Bush Terminal but of more durable construction was made by the New York Dock Department, as shown in Fig. 91, but was abandoned in favor of the design shown in Fig. 70. 156 WHARVES AND PIERS A solid-filled pier without a marginal platform, known as Commonwealth Pier No. 6, and used for the fishing in- dustry, was completed in 1914 by the Board of Directors of the Port of Boston. The pier is 1200 feet long and 300 feet wide. The fill is retained by a granite masonry wall which is illustrated in Fig. 19. Two notable piers are being built at Victoria, B. C., with vertical walls, extending 35 feet below low water, formed of concrete caissons on a rubble mound in water Fig. 91. Design for a Solid-filled Pier, Brooklyn, N. Y. up to 60 feet deep. The wall is shown in Fig. 30. These piers are 800 feet long and 250 feet wide, with a 300-foot slip between them. Another large pier of this type is being built at Halifax by the Canadian Government. It is the first of a group of six similar piers which are planned for a railroad and steamship terminal. The wall in this case is composed of stacks of cellular, pre-cast, concrete blocks filled with concrete and stone which are described on page 63. The choice of this design was influenced by the large amount of rock to be disposed of from the excavation of the slips to PIERS 157 the required depth of 45 feet, and of materials from the large cuts required for the construction of the railroad leading to the terminal. Other considerations were the Fig. 92. Solid-filled Ore Pier with Wooden Sheet Piling, Marquette, Mich. ground swell and waves which rendered the use of floating plant difficult and uncertain. Several of the solid-filled coal and ore docks on the Great Lakes have been described in Chapter IV. A number of these piers have been built recently, in which sheet piling of wood or steel is used to retain the filling instead of the timber cribs formerly used. Fig. 92 illustrates one at Marquette, Mich., in which 158 WHARVES AND PIERS wooden sheet piling is used, and inclined piles are added to increase the stability. The ore bins and their supports are of reinforced concrete. A feature is the sheathing of the face of the concrete with steel plates from 6 inches below the water level to 3 feet above it to prevent disin- tegration by frost and abrasion. Fig. 93 shows one of A-*-, f -Sheer Piling Fig. 93. Solid-filled Ore Pier with Steel-sheet Piling, Duluth, Minn. more recent date at Duluth, Minn., in which steel-sheet piling retains the filling. In these narrow piers the columns supporting the heavy bins are supported on concrete footings, carried on wooden piles cut off just above the water line. These footings also form the exposed facing of the piers. The sheet piling retains the filling, the only function of which is to stiffen the piles and to give a surface on which to deposit the concrete. The sheet piling is supported at the tops by rods embedded in the concrete and extending from side to side of the pier. CHAPTER VI WHARF AND PIER SHEDS SHEDS IN GENERAL THE function of sheds on wharves and piers is to shelter freight and passengers from the elements and to prevent theft Fig. 94. Inshore Elevation, Reinforced Concrete Construction, Chelsea Pier Sheds, New York, N. Y. of merchandise. They are usually used for sorting both in- bound and outbound freight and for its temporary storage while in transit between the vessel and the ware- house, but in some cases are used as warehouses. The general features of their construction are not essentially different from those of similar struc- tures not located on the water front and are usu- ally regulated by the building laws of the cities in which they are built. Fig. 95. Outshore Elevation, Sheet-metal Construction, Chelsea Pier Sheds, New York, N. Y. On deep-pile foundations lightness is of great impor- tance in decreasing the cost, and on piers subject to 160 WHARVES AND PIERS unequal settlement and to distortion from the impact of vessels elasticity is essential. Pier sheds are one or two stories in height. The upper Fig. 96. Inshore End-33rd St. Pier Shed, Brooklyn, N. Y., Showing Sheet- metal Construction. Fig. 97. Front Elevation of Head-house of Hollow-tile and Stucco, Commonwealth Pier 5, Boston, Mass. Fig. 98. Outshore End of Shed, Commonwealth Pier 5, Boston, Mass. story is commonly added for the use of passengers, but there are a few very large piers equipped with two-story sheds on which freight is handled on both floors. WHARF AND PIER SHEDS 161 The inshore ends of pier sheds are often joined to bulk- head sheds, extending along the bulkheads on each side of the pier, and to head-houses on the bulkhead which contain offices and are in many cases two or more stories in height. The fagades of such buildings as well as the outshore ends of the pier sheds call for archi- tectural ornamentation and embellishment to fit the aesthetic requirements of the structure and the locality. Sheet copper or galvanized iron on steel frames which are more or less elastic are fre- quently used where the foun- dations are liable to settle- ment, but on the Chelsea Piers in New York the face wall shown in Fig. 94 is of con- crete reinforced with expanded metal supported on steel girts. As this wall is on filled-in land overlying deep mud, settlement is expected and the wall at the ends of the piers and the steel frame of the bulkhead sheds are arranged so that they can be jacked up independently of each other whenever the necessity may arise. The de- tails of this arrangement are shown in Figs. 100 and 101. Where the foundation is not liable to settlement, brick, concrete, cement mortar on 162 WHARVES AND PIERS metal lath, and hollow tile covered with cement stucco have been used. The equipment of pier sheds with cargo-handling devices is described in Chapter VIII. In this connection may be mentioned a shed of the Tehuantepec Railway which has the novel feature of having removable hatches in the roof, through which the freight is hoisted and lowered by loco- motive cranes. A number of piers in New York and other cities have two-story sheds the upper deck of which is designed for recreation purposes and the lower deck for freight, as illustrated in Fig. 102. FIRE-RESISTING CONSTRUCTION Fire-resisting construction, though it increases the cost and weight, should receive most careful consideration in the de- sign of sheds which are to contain large quantities of valu- able freight. Many existing sheds on both the Atlantic and Pacific coasts are built entirely of wood, but in recent years there has been a tendency to use only incombustible or fire-resisting materials. Unprotected steel frames are sometimes cheaper than those of wood, but do not last as long in case the freight takes fire. Sometimes a combina- tion of the two is economical, as at Seattle, where a two-story shed has timber posts, Bethlehem I-beam girders, and deep timber joists. Some steel frames have been encased in tile to render them fire-resistant, but the increase in weight is considerable and increases the cost of pile founda- tions. The steel columns, second-floor trusses, and joists of the B. A. R. R. piers in Boston are protected with plaster board which is comparatively light and a galvanized sheet- iron jacket has been used in some New York Piers. The unprotected steel frame, when used with an adequate equip- ment of automatic sprinklers, offers some solution of the problem, but to build a really fire-proof shed the frame of which is light, elastic, cheap and economical presents many WHARF AND PIER SHEDS 163 H 164 WHARVES AND PIERS difficulties. Reinforced concrete is heavy and expensive and requires many columns at frequent intervals which obstruct the handling of freight. Plate girder construc- tion has the same objec- tions and is uneconomical in the use of the metal. This problem appar- ently has been solved in large steel pier sheds recently completed in the Panama Canal Zone, by covering the individual members of the roof trusses, longitudinal trus- ses and monitors with cement mortar 1^ inches thick. All the members of the trusses were cov- ered except the upper chords which were en- closed by the concrete roof slabs. Light wooden platforms on wheels were provided for the work- men to stand on in per- forming the work. The steel was first thoroughly cleaned with wire brushes and then cov- ered with expanded Vertical Section Y -Y. Vertical Section x-x. Fig. 101. Details of Concrete Wail, Chelsea Pier Sheds, New York. metal, fastened with wire. Wooden troughs were supported under the horizontal and inclined members and filled with mortar, the mortar over the vertical legs of the angles being shaped with a combined trowelling and screed- ing tool. No forms were used on the vertical members which, together with the joints were plastered and trowelled. WHARF AND PIER SHEDS 165 The cement gun was tried but was unsuccessful because the waste due to the small size of the truss members was Wooden forms for the entire section were also excessive. Fig. 102. Recreation Pier, New York, N. Y. Commerce. Lower Deck used for it'Morhr tried, but on account of the thinness of the mortar coat, could not be entirely filled. The cost of the fire proofing of the trusses was about 12 cents per square foot of floor area (see ap- pendix), and even if the labor should cost much more than it did at Panama, a shed frame of steel protected in this manner f 'Lumber J would, in many cases, be cheaper than Fl s- 103> Fir e-proof- . /. . i .1 n ing for Steel Shed reinforced concrete or any other really Frames , Balboa, fire-proof construction. C. Z. FRAMING Shed posts, except those located in the walls, form a seri- ous obstruction to the movements of wagons and trucks and should be as limited in number as possible on piers on which such vehicles enter. In the North German Lloyd piers at Hoboken, N. J., this was considered to be of suffi- 166 WHARVES AND PIERS cient importance to warrant the extra cost of suspending the second floor from the roof trusses as shown in Fig. 104. About 20 feet is an ordinary spacing for trusses. This fits ten-foot spacing of pile bents and gives an economical length for purlins. Sheds up to 100 feet in width are fre- quently built in one span. For those of 125 feet two spans are economical and for 150 feet three spans give a good arrangement of posts. The usual clearance under roof trusses and under floor beams in two-story sheds varies from 17 to 22 feet. If Fig. 104. North German Lloyd Pier Shed, Hoboken, N. J. travelling cranes and telpherage machines are used for handling freight, this height is increased by from 10 to 15 feet. A quadrilateral form of truss is the most economical for roofs. The longitudinal members of the frames, the bracing of the end walls, and the diagonal bracing in the roof are similar to those of other structures and need no particular description. SIDE COVERINGS The materials most used for the side covering of sheds on pile piers are wood, galvanized sheet iron, and reinforced concrete. On solid-filled wharves which afford good founda- WHARF AND PIER SHEDS 167 tions hollow tile and reinforced concrete are more commonly used. Corrugated galvanized iron is cheap, light, elastic, and incombustible. When exposed to the air, however, it deteriorates rather rapidly when near salt water, and the greatest care should be taken to keep it covered with an impervious and unbroken coating of paint. Before the paint is first applied the galvanized iron should be carefully washed with an alkali in order to insure adhesion. Even with the greatest care it is difficult to make paint stay on it for any length of time, owing to the formation of zinc chloride on the surface wherever the salt air reaches the metal. Corrugated iron protected on both sides with a, layer of asbestos felt treated with asphalt and an outer layer of asbestos fabric has recently been placed on the market. It is claimed for this material that it has all the advantages of galvanized corrugated iron and that it is very durable without painting and requires little or no maintenance. The use of wood for siding is objectionable on account of the exterior fire risk. If covered with sheet metal on the outside this risk is diminished, but it still aids the spread of interior fires. ROOFING The "tar and gravel" type of roof laid on wooden plank has many advantages over other materials in the ease and cheapness with which it can be constructed, its elasticity and lightness, and its resistance to fire on the outside. It has one disadvantage in that unless it is protected on the underside it will aid in spreading a fire. If it is protected by plastering it may be subject to dry rot. This may be prevented by the process known as vulcanizing or similar methods of preservation. Such protection, however, adds to the expense, and the fire risk may be safeguarded to a certain extent by automatic sprinklers. On the B. & A. R. R. piers in Boston the heavy 3-inch roof plank are pro- 168 WHARVES AND PIERS tected on the under side with plaster board. Fire-retarding paints are also of some assistance. Concrete tile is fairly light and has a pleasing appearance, but requires a steep slope, which is objectionable in wide, sheds on account of the resulting height and wind stresses. Reinforced concrete is heavy and inelastic and is liable to be cracked by the impact of vessels on an elastic pier, but it excels in fire-resisting qualities inside and out. Sheds should be provided with a cornice along the sides to form a gutter and prevent the rain water from running off the edges. Down spouts should be carried inside the building. The lower portion should be of steel pipe to prevent damage from wagons and trucks. Cornices should not, however, overhang in such a way as to interfere with cargo-hoisting gear. Sheds are sometimes built with sloping sides, which is of some advantage in this respect, but such sloping sides reduce the storage capacity, do not permit the use of sliding doors, and are unnecessary except for piers for the accommodation of square-rigged vessels. LIGHTING AND VENTILATING Sheds should be well lighted and ventilated. The cheapest method of attaining the result is by the use of skylights and galvanized iron ventilators. Monitor sky- lights with machinery for opening and closing movable sashes are better but much more expensive. Where it is not necessary to provide doors extending in height to the eaves of the shed a row of windows just under the eaves is of advantage. As wired glass in metal frames is one of the best fire-resisting materials the window area should be as large as possible. DOORS The design of cheap and efficient doors for the sides of pier sheds is a subject of considerable difficulty. For steamship piers it is necessary to have the doors come opposite all the hatches in the vessels, and for this reason WHARF AND PIER SHEDS 169 nearly all recent pier sheds have doors in every panel. Doors for freight which is hoisted in and out of steamships and other vessels should be as high as possible to allow the merchandise to be swung inside the shed. Those for freight handled by trucks do not require great height. Doors for pier sheds should be capable of being rapidly closed by one man in case of fire, showers, or heavy winds. There are four types in general use: horizontally sliding, vertically swinging, vertically lifting and folding, and rolling. Horizontal sliding doors are the simplest and cheapest. They are usually made as light as possible, with wooden frames covered with diagonal sheathing boards protected on the outside with sheet metal, as shown in Fig. 105. They are hung on tracks with ball or roller bearing hangers, and where the doors fill every panel in the side of the shed provision must be made for one door to pass another. This type of door is liable to jam when being closed in a heavy wind unless it runs in a groove at the bottom pro- vided with rollers to prevent friction; and such grooves are liable to interfere with freight-handling trucks. On account of the necessary lightness of construction this type is not very durable in the large sizes. For openings 20 feet square on steamship piers such doors are usually made in two leaves and this is about the limiting size for this type. Vertically swinging doors may be of similar construction or may be made much heavier with steel frames and cover- ing. When not counterbalanced they should not reach in one piece below the height of a man from the deck, as they are liable to fall and cause accidents. The lower portion of the opening should be closed by small multiple shutters or by a flap folded back on the upper portion of the door. Swinging doors which reach the deck have also the disad- vantage that they cannot be opened when freight is piled against them. Large vertically swinging doors if strong enough to be durable are so heavy that one man cannot 170 WHARVES AND PIERS raise them without the aid of counterweights and gearing, which add very greatly to their cost. An elaborate door of large size used on the Chelsea piers Dwarf Doors on/y where specified *I5/ Guide Roller ^fjsTSWilcox Wedge If** Wearing Sfrip' bofh sides Sheafhing fo project in 1 "fop and sides fo form rabbet. Ga/v.sfee/ fo be carried inside and lapped over 2 " 1 Fig. 105. Wooden Door for Pier Sheds. in New York City is shown in Fig. 106. The upper por- tion is swung up by means of a fourfold rope tackle. The lower portion is raised vertically in guides at the sides by means of counterweights and gearing operated by a hand chain. It is not connected to the upper portion, but WHARF AND PIER SHEDS 171 the joint between the two parts is closed by a hinged flap. When in the upper position the lower portion overlaps the upper and may be swung up with it. This arrangement allows (1) the entire doorway to be open or closed; (2) the upper portion to be closed and the lower open for the passage 172 WHARVES AND PIERS of men with hand trucks; and (.3) the upper portion open for light and air and the lower portion closed to prevent theft of merchandise. These doors are used in every panel on the sides of the piers and those in adjacent panels WHARF AND PIER SHEDS 173 do not interfere with each other. One man can close them but cannot raise the upper portion alone. Doors to lift vertically are made to fold when raised, as in Figs. 107, as there is not sufficient headroom in pier sheds to make them in one piece. Such doors may be opened when freight is piled close against them. Steel rolling doors for large openings formerly had many objections. They were liable to rust and stick and failed when attacked by fire. They have been greatly improved in recent years and have been placed on many piers of recent construction where the openings are not too large. All patterns which require gearing or other machinery for operation are comparatively expensive and form a large item in the cost of a shed. Wicket or dwarf doors for the passage of watchmen and the escape of men in case of fire should be provided at convenient intervals. Doors at the ends of the sheds are usually of the sliding type divided into units which can be handled by one man or may be of larger size and operated by machinery. PROTECTION AGAINST DAMAGE AND ACCIDENT The exterior corners of sheds should be protected against damage by mooring lines. The outside of lintels and door- posts should be similarly protected against injury by hoist- ing lines, and the protection should be of such materials that it will cause a minimum of wear on the ropes. Exterior walls and all posts and doorways require pro- tection against damage from wagons and hand trucks. Wooden sheathing is commonly used for the inside of cor- rugated iron siding, but it increases the amount of com- bustible material. Wheel guards of various forms are used to prevent wagons from striking doorposts and interior shed posts. The distance between the side of the pier shed and the edge of the pier should be sufficient to provide a safe space 174 WHARVES AND PIERS for handling the mooring lines of vessels. It usually varies from one to six feet. There should be some sort of foot rail on the edge of the pier to prevent men from slipping off. In New York it is customary to make this rail or " backing log" one foot high, but this interferes in many cases with gangplanks and freight handling. A hand rail should be placed on the outside of the shed for further protection against men falling overboard. EXAMPLES OF TYPICAL SHEDS A simple form of truss entirely of wood for a pier 70 feet wide is shown in Fig. 108. This truss is built of planks. Roof Covering -5 lag/ <* Cement on / T& 6 Boards Purlins 3 "*/?"- 26 j ctoc Alfernat ~ Splicing Piece axtOx 6-0 , .6 Camber Fig. 108. Wooden Shed Truss, for 70 Foot Wide Pier, N. Y. Dock Co. It has the advantage that the lumber can be obtained in the sizes used of superior quality at a reasonable price. The large amount of wood surface and the spaces between members of the chords of the trusses are objectionable on account of the fire risk. The sides of the shed were made entirely of steel, to comply with a local building law. The trusses are spaced 20 feet apart. A steel truss on similar lines is shown in Fig. 109. A two story pier shed with timber frame recently com- pleted at Seattle, is illustrated in Fig. 110. It was de- signed for a second floor live load of 300 pounds per square foot and 30 pounds dead load. A maximum fibre stress of WHARF AND PIER SHEDS 175 1,600 pounds was allowed for the timber with 400 pounds per square inch in compression across the grain. A fea- ture is the cast iron caps on the columns which are en- 8x20 Box Sky light- Each Jic/e '\/n d/fernafe Panels /a% Felt ana/ Aspha/f- Ctmertt If 'Dressed Spruce Boards Leaders 40/4parf: Fig. 109. Steel Shed Truss for 70 Foot Wide Pier. Fig. 110. Two-story Timber Shed, Seattle, Washington. larged at the top to increase the bearing area of the beams. This design was chosen in competition with one of steel which required 30-inch I beams in place of the 16 inch by 18 inch trussed, Douglas fir timbers. It was esti- mated that the wooden frame would save 20% over the steel, and that it would last for 20 years. 176 WHARVES AND PIERS Such a frame as this would probably withstand a fire in the contents of the building fully as long as one of unpro- tected steel though the size of the timbers in the roof are rather small for slow burning construction. Fig. Ill shows a very economical shed for a 150-foot wide pier. The trusses are 20 feet apart. Two light wooden sliding doors 20 feet high are used in each alternate panel. A similar truss, but of quadrangular form with cargo masts, is shown in Fig. 112. A shed with steel frame and reinforced concrete sides and (Berts 20' Apartj I (Weight of Steel Frame 2000 Ib. per lin. ft of Sheet) A II I Half Section of Pier-Shed Framing Fig. 111. Pier Shed 33d St., Brooklyn, N. Y. M roof built on a pile pier on deep mud bottom is illustrated in Fig. 113. A similar shed one story high on an adjacent pier was arranged so that the walls were independent of the floor and could be jacked up in case of settlement. The walls, however, gave considerable trouble from cracking. The interior columns and the floor and roof beams of these sheds were not protected against fire in any way. Fig. 114 shows the sheds on the reinforced concrete pile piers at Havana. The columns and roof beams are reinforced with rivetted structural steel strong enough to WHARF AND PIER SHEDS 177 support the forms in order to facilitate erection. The sides and roof are of cement mortar on metal lath with raised ribs. The down spouts for rain water were placed in the centre of the shed columns. 178 WHARVES AND PIERS Fig. 113. Pier Shed with Steel Frame and Concrete Roof and Sides, D. L. & W. R.R., Pier 9, Hoboken, N. J. of Pier No.t ^^^z^^&ssft ^1 ^'Sffrrups ^\: ; i j-nT) 77 IteS^^ i. <. ::. ! -- : .:/ jK _l *L 3ii>x ^ U-^'..>l > (Centra/ Bays) &/ Cross- Sec+ions of Transverse 6irder Fig. 114. Reinforced Concrete Pier Shed, Havana, Cuba. An unusual form of shed is shown in Fig. 115. In this case the posts were placed 10 feet from the sides of the WHARF AND PIER SHEDS 179 building and sliding doors arranged to pass each other were hung from the eave-truss. Grooves formed of angle iron were placed in the deck to hold the lower edges ** ^ of the doors. Fig. 116 shows a tim- ber truss of 100 feet span on the municipal docks of Los Angeles, Cal., also a steel truss of the same . Fig. 115. Sheds on Piers 40 & 41 E. R., size with cargo masts. New Yor k. A steel shed with con- crete roof and siding is shown in Fig. 117. The trusses were spaced 30 feet apart. Section of Outer Harbor Wharf and Shed Fig. 116. Timber & Steel Shed Trusses, Los Angeles, Cal. The two-story steel sheds on the Chelsea piers in New York are illustrated in Fig. 118. The cargo masts are of 180 WHARVES AND PIERS elaborate construction and carry a foot walk for men to rig the hoisting gear. The side covering was of galvanized corrugated iron and the roofs were of felt and slag on plank. The shed on the large concrete pile pier at Halifax is 2j Concrete S/c*b~ wTre Mesh4"*/2'' -V * i Web Members: , ^} D/agrona/^ti, 3x2j* N Vertical - ^ ''A/I Web Members: K- -37-O-"-- >r<- -34 L O-- *~*- -37-O-- ->i Cross Section Fig. 117. Shed with Steel Frame and Concrete Sides and Roof, Pier No. 38, San Francisco, Cal. Fig. 118. Two-story Shed, Chelsea Piers, New York, N. Y. illustrated in Fig. 84. This shed is 200 feet wide and di- vided into five bays. It is designed for a live load of 500 pounds per square foot on the second floor and 110 pounds on the roof. The roof is of concrete, on which is laid a layer of boards and a felt and gravel surface finish. The bents WHARF AND PIER SHEDS 181 are spaced 18 feet apart. The doors of the sliding pattern are in alternate panels in the upper story, but are continuous in the lower. The lower columns are 25 inches in diameter and are protected at the bottom with |-inch steel plates. 'CO I bC Expansion joints were provided in the roof of the shed, but not in either the upper or lower decks. A two-story steel shed for the 1000-foot 46th Street pier in New York, shown in Fig. 118a, although it may be of limited interest in that it is designed for the latest and larg- 182 WHARVES AND PIERS est transatlantic passenger steamers, contains many interest- ing details. The posts are spaced 20 feet apart longitudinally except for a distance of 400 feet at the inner end, where those in the rows on each side of the center line are spaced 40 feet apart in order to reduce the obstruction to wagons and trucks. The depth of the soft mud in the outer portion of the pier rendered the 40-feet spacing impracticable except at the inshore end. The interior posts are 32 feet 4 inches apart transversely, which was considered sufficient for a driveway, leaving unobstructed bays about 50 feet wide on each side. The second floor consists of a reinforced con- crete slab supported on steel beams. Provision is made for depressed railroad tracks on this floor, the depression being filled with a temporary wooden platform, as there is no rail- road connection with the pier at present. The cargo hoist girders on this pier are of structural steel supported on posts spaced 20 feet apart and are designed for two five-ton loads applied five feet from the supports with 100 per cent added for impact. Light and ventilation are afforded by ventila- tors and skylights instead of by the monitors used on the Chelsea piers. CHAPTER VII EQUIPMENT OF WHARVES AND PIERS FENDERS FENDERS have two functions: one is to prevent injury by abrasion and the other is to absorb the energy of impact of vessels coming in contact with the wharf. The necessity Qcof. J. ""p --..-.-............-. _.. ....... ...... .....I.. ^| 4BniisedtoKhorbol'1s, \ '*'?' ! 1 1 l]te*4 _....>U;. ....!_....... ............ / ....... ............. W ..L. -J i-Jv IBruiseJanchorboffs, < *>**/ /J/.,JL- il/f // Z.-. SmkffxR Hip n yis?>/?>/ J^ 2hamfer-- Section A-B Fig. 119. Fender on Concrete Piers, Havana, Cuba. of fenders depends somewhat on the absence or presence of waves, swells, and currents in the water adjacent to the structures. They are almost universally used in this country, but are often omitted from European structures, particularly in the wet docks. Wooden pile structures, on account of their elasticity, need only protection against abrasion, but on inelastic wharves and piers of steel, stone, or concrete, compressible fenders to prevent damage to both vessel and wharf are usually considered necessary. There are some examples, however, of inelastic piers on which the fenders are compressible only to the extent furnished by 184 WHARVES AND PIERS timber fixed to or suspended from the face of the structure. Examples are those shown in Figs. 19, 50, 80 and 119. Fenders are of three general types, fixed, spring, and floating. Fixed fenders may take the form of piles, vertical or horizontal strips, or sheathing. Horizontal strips of heavy timber should be interrupted at frequent intervals with vertical chocks. If this is not done they may be ripped off by tugs and similar vessels which have con- siderable sheer and projecting guards and waling strips. An excellent form of fender for the sides of wooden pile 8x10" Oak TT I II Fig. 120. Continuous Tendering for Wooden Piers. piers is shown in Fig. 2. The piles may extend above the deck of the piers if required. Another form covering the entire exposed portion of the sides of wooden piers for use in places where there are many car floats, scows, and other square-cornered vessels which would damage the fender piles ordinarily used, is shown in Fig. 120. Such fendering should always be put on with a space between the strips in order that persons who fall overboard may climb out on them. The standard corner fender for the wooden piers of the New York Dock Department and the rounded corner used for piers for large passenger steamships are shown in Fig. 2. EQUIPMENT OF WHARVES AND PIERS 185 Fenders for concrete surfaces are shown in Figs. 31, 76, and 121. t-T> _Hor. Section A-B x^ imr [" Fig. 121. Fender for Concrete Wall, Oakland, Cal. \- Top of Mooring ctnot C/usfer Piles A/ Beams under Roof Co/s. have 8 "* * "Cover PL Top c*naf Bottom Detail of Haunch Fig. 122. Spring Fender for Concrete Pier, San Francisco, Cal. A spring fender supported on fender piles for a concrete pier at San Francisco is shown in Fig. 122. It was found, however, that the creosoted exterior por- 186 WHARVES AND PIERS tion of the fender piles was rapidly worn off by vessels and the piles destroyed by the teredo. This required such frequent renewals of the piles that the suspended spring fender shown in Fig. 123 was substituted on piers of recent construction. Floating fenders consisting of round logs or rafts built up of timber are more suitable for masonry walls than for pile structures, as they cause rapid wear of the piles. This is particularly undesirable where the piles are creosoted, as the marine borers attack them as soon as the creosoted Fig. 123. Suspended Spring Fender for Concrete Pier, San Francisco, Cal. exterior portion is worn through. Examples are shown in Figs. 35, 57, 68 and 90. Compressible fenders made of bundles of saplings bound with wire are used on the large concrete-pile pier at Halifax. A fender consisting of a row of spring piles, connected by horizontal wales, located about a foot from the face of a concrete wharf wall but not connected to it, has been used in some places. On the composite pile pier at Port au Prince, Haiti, which is more or less elastic, creosoted fender piles sheathed above water with 8 inches of yellow pine were used, as shown in Fig. 78. EQUIPMENT OF WHARVES AND PIERS 187 MOORING DEVICES Devices for attaching the mooring lines of vessels to a wharf may be in the form of piles, posts, cleats, or rings. Mooring posts, belay posts, snubbing posts, bitts and bol- lards are local names for the same general class of mooring fixture. These fixtures should be designed for use with hemp or wire ropes, arranged so that the lines may be readily attached and detached, and made of materials which will not be easily worn out by use and which will not cause undue wear on the ropes. The diameter should be .large so as not to cause sharp bends in the lines. Mooring devices should also be so shaped that the hawsers of a large vessel the decks of which may at times be far above the deck of the wharf will not slip off. They should be capable of easy replace- ment and renewal when worn out or broken. Timber piles, driven through a properly braced opening in the deck of a wharf structure, or into a Fig. 124. C. I. Mooring Post, f r Piers ' New York Dock Dept. solid fill, are easily worn out, are . . J . subject to decay, and are usually not sufficiently cheaper than other kinds to justify their use for permanent structures. Granite has been tried in some cases, but mooring posts of this material, while they have a handsome appearance, are expensive, brittle, and difficult to replace when broken. Reinforced concrete has also been used. It is, unless protected by metal, rapidly worn out by wire ropes and it wears out the rope. 188 WHARVES AND PIERS Cast iron and cast steel are the most suitable and most generally used materials for this purpose. The large post shown in Fig. 124 has been in use for Fig. 125. C. I. Small Bitt, New York Dock Department. the outer corners of piers for many years in New York. The horns were added to prevent the slipping off of the hawsers of very large vessels. Mooring posts of such great height are unnecessary except at the corners of piers, where it ma y be necessary to fasten a num- ber of lines at the same time. Posts for the corners of piers should b 6 stronger than those on the sides, ag ex ^ ra heavy stresses are put Fig. 126. C I. Mooring Cleat, Qn them in docking ves sels. The New York Dock Dept. _,. , - small bitts, Fig. 125, are used for the sides of piers and are suitable for all but the very largest steamships. Cleats of the pattern shown in Fig. 126 are used for lighters, tugs, etc. They are also used as fair- leaders in connection with corner mooring posts, as shown in Fig. 127. EQUIPMENT OF WHARVES AND PIERS 189 A mooring or " belay" post of steel plate filled with rein- forced concrete was used on the B. & M. R. R. piers in Fig. 127. Corner Mooring Post with Cleat used as a Fair-leader. Boston. Fig. 76 illustrates a form of "bollard" common in European practice. An unusual form of double bitts was designed for the piers re- cently built in San Fran- cisco and is shown in Fig. 123. An excellent form of mooring post is that used on the concrete wall at Oakland, CaL, shown in Fig. 128. Other forms are shown in Figs. 13, 18, 51, and 77. The usefulness of double Fig 12g Mooring Post> Oakland> Cal posts or double bitts on a wharf is not apparent where the mooring devices are used 190 WHARVES AND PIERS simply to hold a line in the end of which a loop is spliced or tied. Appliances of this form are more useful on the vessels where the lines are handled, adjusted for length, and made fast. Mooring rings are sometimes placed in the faces of Fig. 129. Wharf Drop. masonry walls or on the top. They are not to be recom- mended, as they are clumsy, inconvenient, and cause sharp bends in the hawsers and consequent injury. WHAKF DROPS Wherever it is necessary to transfer freight between wharf and vessel by means of trucks in localities where EQUIPMENT OF WHARVES AND PIERS 191 there is a considerable rise and fall of the water surface, " wharf drops" or movable gangways are required. These are sections of the deck hinged at one end and suspended from overhead frames at the edge of the wharf so that they may be raised or lowered by hand-power gearing or by electric motors, as shown in Fig. 129. It is evident that if more than one of these gangways is to be used on a vessel at the same time they must be located to match the side ports of the vessel. These gangways may be fitted with electrically driven chains equipped with projections to engage the axles of freight trucks and assist them up the grade, as described in Chapter VIII. PAVEMENTS Pavements for wharves should offer a good foothold for men and horses. They should be smooth where trucks for moving freight are used. They should be non-absorbent, so that water and other liquids cannot soak into them. The wear on wharves where there are many horse-drawn trucks is frequently concentrated in narrow lines, and on many wharves the traffic is so dense that pavements wear very rapidly. Such pavements should therefore be easily removed and repaired when worn out. Those for pile wharves should be light in weight. The substances used for pavements and wharves are plank, concrete, sheet asphalt, wood block, brick, asphalt block, and granite block. Plank is the least durable material, but it is absorbent, and where there are very many horse-drawn trucks it acquires an offensive odor. It is, however, light, elastic, and low in price. Pacific Coast white cedar is said to be superior to other woods for this purpose. Vertical grain fir is also used on the Pacific Coast. In New York 3-inch yellow pine sheathing requires complete renewal after six years. In San Francisco Douglas fir is said to have lasted only one year and white cedar two years. Concrete is low in first cost, but it is very difficult to 192 WHARVES AND PIERS make it durable where there is much horse trucking. The grinding action of heavy loads on narrow-tired wheels, due to the frequent turning necessary in manoeuvring wagons in the narrow roadways, is particularly destructive to it. A light sheet asphalt pavement on a concrete base has been found very satisfactory. It is cheap, elastic, and can be easily repaired. In New York a pavement 2| inches thick costs only from 10 to 15 cents a square foot with a five-year maintenance guarantee. An objection to such pavements, however, is that they are liable to be indented in warm weather by sharp objects, such as the ends of casks and barrels. Sheet asphalt pavements the surface of which is composed of broken stone and sand are less subject to this defect than those made with sand only. Pavements of creosoted wood blocks have been used with great success on many piers. They are light and can be laid directly on either plank or concrete foundations, but the first cost is very high, and where there is little traffic the blocks are said to shrink and become loose. In Philadelphia the price is about double that of asphalt. Brick, asphalt blocks, and granite blocks are, on account of their weight, more suitable for solid-filled wharves than those on pile foundations. They are somewhat difficult to repair satisfactorily when unevenly worn. RAILROAD TRACKS Where it is necessary to have railroad tracks on a pier they may be placed in the middle or at the edge and may be placed at the elevation of the surface or depressed so that the floors of the cars are on a level with the deck. They should be arranged so as to waste as little wharf space as possible and to produce a minimum cost in handling the freight. Depressed tracks have the great disadvantage that they form a barrier against the movement of trucks. They may be crossed on movable bridges, but the latter interfere with the shifting of cars. Where motor trucks are used EQUIPMENT OF WHARVES AND PIERS 193 for handling freight, portable platforms and ramps may be used to enable trucks to enter box cars, instead of de- pressing the tracks, and where overhead cranes or telephers serve the cars, portable platforms will provide all the advantages of depressed tracks. The space occupied by depressed tracks cannot be used for any other purpose, while if the tracks are at the level of the top of the wharf the space occupied by them when not filled with cars can be used for trucks or storage. A double track in the middle of a pier wastes less deck room than a track on each side and has the advantage of permitting the installation of cross-overs between the tracks which facilitate the shifting of the cars. A single track on each side of the pier can seldom be kept full of cars, and, even if not depressed, the space it occupies on a shedded wharf cannot be used for other purposes when not occupied by cars. If the tracks are placed on the sides of a pier there is some saving in the width of the shed required. It is seldom practicable to transfer general cargo, with the appliances in use at present, directly from car to ship or from ship to car. In the first case a double track on the side of the wharf is required with frequent cross-overs if more than one hatch is to be loaded at the same time and the loading is not to be interrupted by the shifting of the empty cars. It does not pay to run a travelling crane longitudinally on a wharf for transporting freight from the end of a string of cars to the vessel's hatch, as so much time is lost in travelling that it is usually cheaper to keep the crane stationary and transport the goods from the car to the machine by hand or motor trucks. In unloading a vessel the freight nearly always has to be sorted before it can be put in the cars. Direct transfer between car and vessel is much more common in Europe than it is in this country. This is probably due to the nature of the rolling stock. The cars used abroad are very much smaller than ours and open cars 194 WHARVES AND PIERS or what are termed " gondolas" in this country are used for everything but very small and valuable packages, the freight being protected from the weather by tarpaulins. Our box cars are not adapted for rapid loading and unload- ing with cranes or telephers, but it is possible that as the demand for the use of such machines increases, box cars will be made with removable roofs so that they may be loaded and unloaded without the use of platforms or hand trucks. In New York there is considerable direct transfer of freight between cars and lighters. It is to a great extent limited, however, to machinery and similar goods carried on flat or gondola cars. Special piers are provided for this purpose, equipped with several lines of tracks and with locomotive revolving cranes or gantry cranes of the pattern shown in Fig. 140. FIRE PROTECTION The fire risk on freight piers is considerable, both external and internal. Fires on wooden wharves have frequently resulted in the total destruction of the structures them- selves, the freight, and the vessels lying alongside. There have been cases, however, where the sheds and freight have been destroyed and the wooden pier decks were not even burned through. The principal risk is from the cargo, which is often of much greater value than the pier and shed, so that it is of more importance to safeguard the cargo from fire than the wharf structures. Among the most usual known causes are defective electric wiring, spontaneous combustion of baled cotton, fires on vessels alongside, and burning oil floating on the surface of the water. Many wharves have been constructed, not only without any regard whatever to fire protection but in such a way as to increase the risk in many unnecessary ways, and it is only within the last few years that much attention has been given to this subject. The general requirements for protection against fire are, for piers and sheds, as follows: EQUIPMENT OF WHARVES AND PIERS 195 1. The division of the space in the sheds and under the deck of the pier by fire walls, with self-closing fire-proof doors in all openings, in order to confine a fire to a com- paratively small space and to permit of its being extinguished by the firemen. This is the most important of all the requirements. 2. The use of automatic sprinklers properly maintained and inspected, also of water curtains along the outside of pier sheds. 3. The use of materials which are not destroyed by fire, such as reinforced concrete and steel encased in concrete or tile; or which resist fire, such as heavy timber and the elimination of destructible materials such as unprotected steel frames, wooden beams, joists, and purlins of small section, and wooden siding. 4. The use of automatic alarms. 5. The installation of fire buckets, chemical extin- guishers, and hose. 6. The elimination of openings as far as possible in the upper floors of sheds which are more than one story high. The enclosure of all elevator shafts, stairways, and other openings with fire-proof walls, equipped with self-closing fire-proof doors. Fire Walls. - - The huge undivided space in large pier sheds has often acted as a furnace when filled with freight. If the fire starts with the doors open at both ends it spreads with incredible rapidity so fast that men at work on the piers have no time to escape except by jumping overboard. The heated gases sweep through the shed and set every combustible thing on fire. If the fire once gets under way, buckets, extinguishers, and hose cannot be used. The shed if not built of fire-resisting materials usually collapses in a few minutes, the roofing makes the efforts of the firemen of little use, and the fire usually burns itself out. To make fire walls effective the openings in them should be as few and as small as possible and should be fitted with self-closing fire-proof doors. Such walls in the sheds are 196 WHARVES AND PIERS inconvenient, as they interfere with the handling of the freight and are strenuously objected to by most pier super- intendents, but these objections are being overcome and the use of walls is rapidly increasing. The use of thin wooden deck joists and of pile caps and rangers or stringers in pairs, separated by a narrow space, are particularly objectionable as far as the fire risk is con- cerned. Such caps and rangers afford the best possible conditions for maintaining a fire under the deck of a pier and are most difficult to reach with fire hose. To offset this objection the New York Dock Department places reinforced concrete fire walls about 300 feet apart in their wooden piers, extending from the deck to low water and from side to side of the pier, with hatches in the deck at intervals of about 50 feet to provide access for firemen to the space underneath. Such walls help to confine a fire under the deck of a pier to a small area. Sprinklers. - 1 The automatic sprinkler is the best and most economical method of prevention and control of fires on piers and wharves and costs only about 10^ a square foot of floor space. The installation and maintenance in efficient condition of this device in a pier shed is of more importance than the construction of the shed of materials indestructible by fire, as the sprinklers protect the freight as well as the shed, even if the latter is built of materials which do not resist fire. It is the freight which usually furnishes the greater part of the fuel, and often causes a greater money loss than the shed. Even if the shed is of the best fire-resisting construction the sprinklers should in no case be omitted if freight is to be stored in it at any time. It is only of late years that sprinklers have been used on piers and their use is spreading but slowly. This is due in some instances to lack of capital and perhaps some explana- tion may be found in the way in which the interest in fire protection is divided among the parties which own and use the " pier. For example, one company may own a pier and rent it to a steamship company which carries freight EQUIPMENT OF WHARVES AND PIERS 197 owned by individual shippers. The latter pay for the insurance on the cargo, which is carried by the steamship company and is included in the freight rates, and they supply the greater part of the fuel in case of fire. The steamship company which leases the pier maintains and inspects the sprinkler system, which is owned by the party who owns .the pier. The owner is interested in the possible loss of income if the pier is burned, but as it is difficult for him to make sure of the proper care and in- spection of the apparatus, without which it is worthless, he hesitates to spend money on the installation. The interest of the steamship company lies in the decrease of the risk of destruction of freight and vessels lying alongside the pier, and in the decrease of rent which includes the insurance on the pier, and in a possible decrease in the insurance of the freight. The shipper is only slightly interested, as the difference in freight rates due to the sprinklers on a pier may be com- paratively unimportant. It is difficult to understand why the owners and lessees of piers do not see the advantage of sprinklers, which is shared by both, in a stronger light and why any difficulties in maintenance of the apparatus cannot be obviated by clauses in the leases requiring proper .maintenance and inspection by the companies which make a specialty of such work and are thoroughly reliable. The best practice requires that a sprinkler system should be supplied with water from at least two different sources, one of which should be an elevated tank properly protected against frost. The other supply should be from the city mains, if available, or from fire pumps. Connections should be supplied at both ends of the pier for fire engines and fire boats. The dry-pipe system of water distribution is necessary on piers where water in the pipes is subject to freezing. Cornice sprinklers or " water curtains" should be installed on the outside of the sheds for protection against exterior fires, such as burning ships. Perforated pipes 198 WHARVES AND PIERS with connections for fire boats and fire engines have in some cases been placed under the decks of wooden piers. Roof Hydrants. Roof hydrants are useful for fighting fires on ships and lighters lying alongside a shedded pier. Fire-resisting Materials. - - The use of fire-resisting materials, such as reinforced concrete or steel encased in hollow tile or concrete, makes a pier shed so heavy that it increases the cost of a pile foundation very considerably and for this reason structures having fire-proofed walls, frames, and roofs are unusual on pile piers. Their number, however, has increased considerably in recent years. Unprotected steel roof trusses or second-story floor beams, though incombustible, will collapse in a very short time if subjected to a fire in the freight under them, as has happened in many instances. Such collapses have often resulted in the fire burning itself out as stated above. Heavy wooden columns and trusses will stand up much longer in a fire than unprotected steel, but are usually so reduced in section after a fire that they have to be replaced. They are useful in that they are slow burning and permit of effective work by firemen in saving the cargo. The sides of a shed should always be of incombustible material and all glass in windows and skylights should be wired. Piers which are constructed of wood between the water and the deck are subject to fire risk from vessels alongside and from floating burning materials. They may be pro- tected from this risk by sheathing on the outside, provided that sufficient ventilation is provided under the deck to prevent rot, as has been described in previous chapters. Automatic Fire Alarms. Automatic fire alarms which operate from local application of heat should be used in sheds to give notice of incipient fires in the freight. Miscellaneous Equipment. Piers should be equipped with fire buckets and in cold climates with tanks of water to which enough salt has been added to prevent freezing. Such tanks, containing both salt water and a number of EQUIPMENT OF WHARVES AND PIERS 199 buckets, are sold by the dealers in fire-extinguishing supplies and are most suitable for the conditions existing on piers. Hydrants and hose should also be installed and should be arranged so that they will not be obstructed by freight piled in front of them. Watchmen's clocks should be included in the fire pro- tective apparatus in order to ensure the efficient patrol by the men employed for the purpose. CHAPTER VIII CARGO-HANDLING MACHINERY GENERAL CONSIDERATIONS THIS chapter treats of machinery for handling package freight and does not cover apparatus for bulk cargoes, such as coal, ore, grain, and oil, for which special machinery is required for each kind of material. Object. The object to be attained by the installation of freight-handling machinery on wharves is the reduction of the cost of transportation by saving in the cost of labor, by increasing the speed of loading and unloading vessels, and by reducing the cost of high tiering of freight on the wharf. The increase of speed increases the efficiency of the vessels by increasing the tonnage carried by ships in a given time, and economical high tiering reduces the area of wharf necessary to handle the required amount of freight. Function. - - The function of cargo-handling machinery for wharves is the transfer of freight between the wharf and the vessel and its transportation on the wharf. The commonest method is by use of the ship's hoisting gear and two- wheeled or four-wheeled longshoreman's hand-trucks. This method may be made very' rapid, but it is very ex- pensive, the principal factors being the large amount of highly paid labor and the large area of wharf required. Up to within a few years ago little progress had been made in reducing the cost of cargo handling by the introduction of improved machinery and appliances. Some explanation of this may be found, as in the case of fire protection, in the number of parties involved in the various operations. For example, one company may own the wharf and shed and lease them to a steamship company which makes a CARGO-HANDLING MACHINERY 201 contract with a stevedore, at so much a ton .for unloading the freight, which he deposits on the pier for the consignee's truckman to take away. It is difficult under such condi- tions to obtain cooperation among those interested and to introduce new methods and machinery involving large outlays of capital, the abolition of long-established customs and emoluments, and the overcoming of the objections to the introduction of labor-saving devices. In a very few instances, however, all the operations involved in the transfer of freight between vessel and consignee are con- trolled by one party, and where such conditions occur, may be found progressive policies and methods, and the success- ful use of machinery with reduction in cost and increase of efficiency of vessels and wharves. Another reason why improved machinery has been intro- duced to such a small extent may be found in the fact that the advantage of any machinery involving high fixed charges depends largely on the "load factor," or ratio of employed to idle time. Where freight handling is con- ducted night and day the opportunity for economies by its employment is much greater than where such an equipment is only in use say one fifth of the time, as is often the case. Operations to be Performed. The operations to be performed in cargo handling may be divided into three classes : 1. Hoisting and lowering on the steamer, lighter, or other vessel. 2. Transfer between the vessel and the wharf shed, warehouse, car, dray, or another vessel. 3. Transfer between the shed and the warehouse, car, or dray. Incidental to the transfer are sorting, weighing, gauging and measuring, marking, customs examining, sampling, recoopering, and checking. On outbound freight, in order to keep the idle time of the vessel at a minimum, the sorting is usually limited to 202 WHARVES AND PIERS putting the freight for each port of delivery together and stowing it with reference to its weight, bulk, and perisha- bility. When the vessel has only one port of call a large part of this sorting is eliminated. The result of this kind of loading is that when the cargo is unloaded it comes out of the ship with the consignments all mixed together. The sorting is usually done on the wharf, in order to save the vessel's time, and, with the other incidental operations, forms the greatest obstacle to the economical use of machinery on the wharf. The average consignment may vary from half a ton to one or more car loads, and the cost of handling and the possibilities for saving by the use of machinery depend to a considerable extent on this average size. In the sorting of small consign- ments the two-wheeled hand truck has the greatest ad- vantage and motor trucks, telphers, or other carriers of large capacity are inefficient. It is obviously impossible to formulate any general plan in regard to cargo handling and the object of this chapter is to describe various conditions which, in various com- binations, may have to be provided for, and the methods and machinery in use. Classification of Vessels. --Vessels may be divided, for consideration in connection with cargo-handling machinery, into those in which the cargo is hoisted on and off and those in which the cargo is trucked on and off. Trans- oceanic freight ships usually load their cargo through comparatively small hatches in the deck. Many coastwise vessels which carry both passengers and freight have extensive deck houses, few deck hatches or none at all, and load partly or wholly through side-ports, by means of trucks. On side-port vessels having more than one cargo deck, the cargo is hoisted from the lower decks to the deck on which the trucks enter by means of elevators or cranes installed on the ship. Bay, sound, and river steamboats usually are in the second of the above classes. Canal boats are in the first class but do not carry hoisting gear. Derrick CARGO-HANDLING MACHINERY 203 lighters are in the first class and covered lighters in the second. Heavy Packages. Packages weighing over five tons cannot usually be handled by the ship's gear. Floating cranes and derricks are used in most ports for this purpose, as it is not economical to equip the wharves with machinery capable of handling occasional loads of such weight. CLASSIFICATION AND DESCRIPTION OF MACHINERY AND APPLIANCES Machinery for freight handling may be classified into that used for hoisting and transporting. The ap- pliances for hoisting are cargo booms, winches, hatch-cranes and elevators, on the vessels, and cranes of various patterns, telphers, cargo masts and portable winches on the wharves. Fig. 130. Two-wheel Freight Truck. Fig. 131. Four-wheel Freight Truck. For transferring freight between vessels and wharf shed there are, in addition to all the above, except the ships' cranes and elevators, two and four-wheeled hand trucks, 204 WHARVES AND PIERS motor trucks, and portable conveyors, and for transporting freight on the wharf there are, in addition to these, flat- boards or low four-wheeled trucks drawn by horses or mules, motor trucks with trailers, and overhead travelling cranes. Other appliances are portable electric controllers, inclined truck elevators, slides between wharf and vessel, and chutes and other devices for use be- tween the floors of double deck sheds. Ships' Gear. Freight ships for trans-oceanic trade are usually equipped with masts and from two to seven cargo booms and winches to each hatch. Fig. 133 shows a recently built type of freight steamer with a very elaborate equip- ment of cargo gear which permits of handling cargo from each of the two largest hatches on both sides of the ship at the same time. One cargo boom on each mast is designed to handle extra heavy loads. Fig. 134 illus- trates a steamer with the or- Fig. 132. Loading Ship with Inclined Skid. dinary equipment of cargo booms. The winches are placed on raised platforms to permit the operators to see into the hold. This platform is only found on the newer ships. Fig. 135 shows a lumber schooner with very high booms and elevated platforms for the winches. The usual method of unloading with this equipment is to rig the booms of each pair at about 45 with the keel, hoist the load with both lines, and lower it with one. In loading the opera- tion is reversed. With this arrangement the cargo can be CARGO-HANDLING MACHINERY 205 H hi | SI I H t q i :l S 206 WHARVES AND PIERS handled on either side of the vessel without shifting the booms. The winches are arranged so that one man handles both lines and the extended operating platforms permit of a good view into the hold. The type of winch in which the rope is not wound on a drum but on an extension winch head, thus re- quiring an operator for each line, is much in use and is apparently wasteful of labor. Double and triple drum, steam-driven winches, which wind the rope on the drums, are rapidly and safely operated by one man in handling derricks on land, and there is no obvious reason why similar machines should not be used on ships and wharves. Winches of this nature have re- cently been placed on the market and are shown in the illustrations. Hatch cranes and elevators for vessels which load through side ports are shown in Fig. 138. Wharf Machinery. Wharf machinery is operated by steam, hydraulic, or electrical power, but the latter is almost universally used in new installations. Cranes. Of wharf cranes there are several patterns. The revolving crane is the most common. This consists of a derrick with a boom or jib which may be raised or lowered by an independent motor mounted on a turn-table which is carried by some sort of a car moving on tracks. The car may be of the ordinary low railroad type or may be of the " portal crane" or " gantry" type in the form of a movable bridge, spanning a roadway or one or more railroad tracks on the side of the wharf or pier. One of the rails may be placed on the side of a shed, in which case the machine is called a "semi portal crane." Such machines are usually built with little regard to the load on the track and are very heavy on account of the counterweights which are employed to balance the boom and the moving load. This is of considerable disadvantage on pile foundations, and some recent machines have been designed in which the weight has been reduced as much as possible. Revolving CARGO-HANDLING MACHINERY 207 I I I n o J= E' H -a 208 WHARVES AND PIERS CARGO-HANDLING MACHINERY 209 cranes are also mounted on cars which run on the roofs of freight sheds. Roof cranes may also be of the " straight line" type with Fig. 136. Ordinary Type of Ship's Winch: Two Lines Operated by Two Men. Fig. 137. Winch for Two Lines operated by One Man. a vertically hinged arm carrying a trolley. Another pattern has the trolley arm suspended on trunnions in such a way that when it is in position for operating, it extends both over 210 WHARVES AND PIERS the vessel and inside the door of a shed so that the loads can be landed inside the latter. Telphers. - - Telphers are electric cars running above the Fig. 138. Hatch Cranes and Elevator for Ships with Side Ports. Fig. 139. Electric Locomotive Crane. deck of a wharf at a height sufficient to clear the cargo, on single rails suspended from frames, either those of a freight shed or, in the case of an unshedded wharf, those CARGO-HANDLING MACHINERY 211 erected specially for the purpose. The car carries its motors, the operator, and electrically operated hoists for raising and lowering the loads. Each motor car may also be provided with a number of trailers similarly equipped with hoisting gear. The loads are carried in crates or on "flat boards" suspended from the motor car or trailers. If the tracks are fitted with fixed switches they require many parallel lines of rails to cover a given area. A device called a gliding switch has been used considerably in Europe, and to a small ex- tent in this country, which permits a rail on a travel- ling bridge or shop crane to be connected with another rail at right angles to it wherever the travelling crane may be, as shown in Fig. 145. This device allows such a travelling crane to be substituted for the nu- merous parallel cross rails Fig. 140. Gantry or Portal Crane. necessary in the system using fixed switches. The combin- ation of a travelling bridge crane fitted with rails' and gliding switches permits the telpher to serve the entire area served by the travelling bridge. New York Cargo Hoists. Cargo hoists, such as are shown in Figs. 96, 112, 116 and 118, have been developed in New York for transferring cargo between the wharf and steamships equipped with cargo booms and winches. For want of a better name they may be called the New York Cargo hoist. They consist of upright steel or wooden columns at the side of the pier shed which support wire cables or steel girders to which cargo-hoisting pulleys or blocks may be attached. The function performed by these hoists may be performed by an extra cargo boom on the ship, but they have the advantage of supplying a point of 212 WHARVES AND PIERS suspension for the block at the best location, which cannot always be supplied by the ship's boom, especially when the Fig. 141. Semi-portal Crane. ship is moored at some distance from the wharf to allow coal lighters to lie between the ship and the wharf. Fig. 142. Straight Line Crane on Roof of Wharf Shed, Rotterdam. Portable electric winches are used on the wharves to operate whips or single hoisting lines rove through the blocks on the cables or girders between the cargo masts. CARGO-HANDLING MACHINERY 213 Motor Trucks. Electric freight trucks operated by stor- age batteries have been placed on the market in recent years to take the place of hand-operated trucks. They have a capacity of about two tons and a speed of five to seven miles an hour. Some of them are arranged to run under a skid or platform with short legs, raise it a few inches, and Fig. 143. Straight Line Crane delivering Freight inside Wharf Shed. transport it with its load of freight. If these skids, which are inexpensive, are supplied in excess of the number of motor trucks, the efficiency of the motor truck is increased by reducing the time spent in loading and unloading it. Some motor trucks are fitted with cranes and some are designed to act as locomotives and haul a number of trailers. Conveyors. Portable, electrically operated conveyors, such as are illustrated in Fig. 150, are used for transferring freight in uniform packages, such as sugar, coffee, cement, canned goods, etc., from the vessel's hatch to the wharf. 214 WHARVES AND PIERS They are made in sections which can be easily moved about. A slightly different form is used at the end of a line for tiering. Portable Controllers. Portable electric controllers have been used for some years in Europe and have recently been Fig. 144. Telpher Train. put on the market by one of the large electric manufacturing companies in this country. They are carried on a belt worn by the operator and are connected to the motors of a hoisting winch or crane by flexible electric conductors. By use of this device the operator of a hoisting machine can stand at the edge of a ship's hatch and see the load he is hoisting at all stages of the operation, thus increasing the speed and dispensing with the services of signalmen. As they are made to control two motors, one man can operate a double-drum winch or two machines, such as a ship's winch and a dock winch. CARGO-HANDLING MACHINERY 215 Inclined Truck Elevators. Inclined truck elevators con- sist of electrically driven chains running in a slot in a wharf- drop or inclined ramp. The chains are fitted with lugs or hooks which engage the axles of hand or motor trucks and carry them up the grades on which they require assistance. LOADING AND UNLOADING SHIPS Cranes vs. Ship's Gear. --The two principal appliances in use for hoisting freight to and from vessels not equipped with side ports are the ship's cargo gear and wharf cranes. In Europe the wharf crane is the most common and in this A c' . c B \lr * '/$- - ii ii n |D' Moveable Bridge D or ,. Transpherer i & 1 i . x N> S^> > Y Fig. 145. Travelling Bridge with Gliding Switches. country the ship's tackle is almost universal. When the ship's tackle is used one hoisting block is suspended from the end of a cargo boom over the hatch and another from another boom or from the cable or girder between the cargo masts on the wharf, over the point on the wharf where the load is to be deposited. Two lines are attached to the sling which carries the load, each leading to a drum of a hoisting winch. The load is first raised by one line, then transferred to and lowered by the other line. Where wharf cranes are installed, they are usually used to hoist the freight from the hold of the vessel but sometimes the cargo is hoisted to the deck by the ship's winches and transferred to the wharf by the crane. The comparative advantages of the two methods may be summed up as follows: The revolving crane wastes time in its rotary motion and the length of the path described by the load, also in stopping the hook or load at the proper 216 WHARVES AND PIERS point. The crane is limited in its action by the shrouds on the ship's masts. The modern ship's gear is said to be as rapid on package freight as the revolving crane, even though the latter may lift a larger load. The crane requires Fig. 146. Telpher System with Gliding Switches for a Freight Pier. a larger outlay of capital than the New York cargo hoist and dock winch, and may be in use only a small portion of the time. It is often heavy and increases the cost of founda- tions in pile structures. It requires only one operator, while the two-line method usually requires two or more. This disadvantage may be overcome, however, by means of the portable electric controller described above. The crane is a necessity where cargo is to be transferred to and from barges and other vessels which have no cargo gear. The modern crane and the modern portable electric dock winch combined with the New York cargo hoist are CARGO-HANDLING MACHINERY 217 both much superior in speed, and require fewer men to operate, than the ships' winches in ordinary use. For this reason they should, where there is sufficient traffic, be placed on wharves and piers except in cases where the ships using the wharves are equipped with an ample number of cargo booms and winches of the most economical type. =13 'TiTttf Fig. 147. New York Cargo Hoists, showing Use of Winches on the Ship and on the Pier. The New York cargo hoist is more economical than the crane, is fully as rapid, and is therefore superior wherever it fulfils all the conditions. The crane serves a larger area than the ship's tackle and can, therefore, prevent congestion on the wharf due to delays in clearing the point where the freight is landed. The straight-line crane does not serve so large an area as those of the revolving type, but its load does not have to follow as long a path. In loading vessels the loads are often dragged up an inclined skid or slide between the wharf and the ship, thus 218 WHARVES AND PIERS avoiding the use of two hoisting lines and the accompanying labor. It is somewhat difficult to understand why the use of cranes is so prevalent abroad and so exceptional in this country, and why, when a steamship company with almost unlimited capital, a few years ago, rebuilt its piers which had been burned, it equipped them with the New York pattern of cargo hoists when the piers of the same company Fig. 148. Electric Motor Truck. in Germany are equipped with over one hundred revolving cranes. Many reasons have been suggested. One of them is that the crews are discharged and fires drawn in home ports in Europe, but retained here, and that boilers, winches, and crew are available here to work cargo. On the other hand, it is stated that one line of steamships handles cargo in its home port in Europe with the ship's gear, though the wharf is supplied with cranes ; moreover, most ships are fitted with donkey boilers for operating winches, etc., when the main boilers are out of use. Besides this, the dock winch with the portable controller would be sufficient even if there were no power available in the ships. Another reason given is that the tidal range in some European ports is so great CARGO-HANDLING MACHINERY 219 that ship's tackle cannot be used to advantage when the tide is low. The New York cargo hoist would solve this problem Fig. 149. Motor Truck with Separate Cargo Platform. as well as the crane. Another possible explanation is that the cranes are supplied by the municipalities which own the docks, and that the steamship companies would not in Fig. 150. Sectional Portable Conveyor. many cases install them at their own expense. Probably the best reason is that at nearly all European ports there are a great many deep-hulled barges and similar vessels 220 WHARVES AND PIERS which have no cargo gear at all and that many steamships are more or less deficient in their equipment of booms and winches, and that the revolving crane has a greater range of usefulness than any other form of cargo-handling ma- Fig. 151. Portable Electric Controller for operating Winches on Wharves or on Ships. chinery. In New York, practically the only vessels which have no cargo gear which come to steamship piers are those which unload their freight by means of trucks from deck to wharf, and coal barges for coaling ships. The coal is hoisted by means of light temporary booms, ship or dock winches, or winches on small scows which accompany the coal barges. When the New York State Barge Canal is CARGO-HANDLING MACHINERY 221 completed it is expected that the vessels which will be used on it will be of over 2000 tons' capacity and that they will carry their cargoes in hulls about 12 feet deep and that they will have no cargo gear. It is probable that the wharves constructed by the State at the terminals on this canal will be equipped with cranes for cargo handling. Neither the New York cargo hoist nor the crane will transfer freight between a steamer at a wharf and a barge or lighter lying on the opposite side of the vessel. The ships' tackle may perform this work if the hatch is large Fig. 152. Portable Electric Winch with Two Independent Drums and Portable Controller. enough while a wharf crane is working on the opposite side of the steamer. If a steamer is equipped with only two cargo booms to a hatch the New York dock cargo hoist could not be used while freight is being transferred between ships and lighters unless a temporary boom were rigged up. Speed-limiting Points. --The limiting point of speed in loading and unloading is usually on the vessel. The rate at which cargo can be handled is not limited ordinarily by the speed at which the hoisting apparatus can be operated but by the rapidity with which the cargo can be stowed in the hold or broken out and made up into loads for hoisting. With some kinds of cargo, when ships' gear and hand 222 WHARVES AND PIERS trucks are used, the limiting point in unloading may be the landing point on the wharf, but such a condition is unusual. Reservoirs. As the operations in the vessel as well as those on the wharf are both subject to interruption and irregularities and in order that one may not delay the other and cause men and machinery to stand idle, a reservoir or place of deposit must be provided between the two Fig. 153. Inclined Truck Elevator. operations where the freight may accumulate and diminish. It is essential that there should be ample deck space at the point where freight is landed on the wharf by cranes or ships' gear to supply such a reservoir, and that, in order to avoid extra handling in the reservoir, an adequate supply of extra carriers should be provided except where the two- wheeled truck is the only means of conveyance. An ex- ample illustrating the above is found in unloading coffee in bags. The latter were hoisted by the ships' gear and deposited on four-wheeled platform trucks. Only enough trucks were provided to equal the capacity of the hoisting CARGO-HANDLING MACHINERY 223 apparatus. In spite of all efforts the trucks became grouped and there were times when it was necessary to stop the hoisting and with it the work of a large gang of men in the hold of the vessel, or deposit the bags on the deck of the wharf, to be subsequently loaded on to the trucks by addi- tional labor. A reservoir consisting of an inclined slide with a capacity of two or three truck loads obviated the difficulty and made the hoisting apparatus the limiting element of speed. A similar condition may occur at the end of a line of conveyors. FREIGHT HANDLING ON THE WHARF The cost of freight handling may be divided into that incurred on the vessel in stowing and breaking down cargo, the transfer between yessel and wharf, and the handling on the wharf. The average cost of unloading steamships has been estimated as follows: Hoisting and lowering with cranes $0. 02 to 0. 05 " with two winches ... $0. 04 to 0. 10 Distributing and tiering $0. 29 to 0. 36 Loading on drays $0. 20 Sorting before hoisting doubles the cost of hoisting and lowering. As there are almost no mechanical devices for reducing the cost of the work in the vessels' holds, and as the cost of transfer between vessel and wharf is only about one fifth of the cost of handling the freight on the wharf, the latter becomes the main point for attack in reducing the cost. The principal appliances which today are available for this purpose, in place of the ordinary hand trucks, are storage-battery trucks and telphers. Other appliances to be considered are horse-drawn trucks, conveyors, and stackers. Hand Trucks. - - The two-wheeled longshoreman's truck transports a large load for one-man power, it is very flexible, allows of rapid sorting of small consignments, can be operated in narrow roadways, and has very low fixed charges for 224 WHARVES, AND PIERS interest repairs, depreciation, and insurance. It can be made rapid in operation, but it is high in labor cost. It can perform any of the functions of the other machines mentioned above except tier and load drays or railroad cars. It requires no expensive overhead structure or extra founda- tions, but it does require a smooth surface to operate on. Electric Trucks. - - The electric truck carries a larger load than a hand truck, moves faster, and requires less labor, but has a very high first cost, high charges for interest and insurance, a high maintenance cost, and should be charged with a high rate of obsolescence. It can go up grades without extra cost for labor, and, by means of portable ramps, it can enter box cars standing on the deck of the wharf. Equipped with a crane, it can load drays and cars, transport heavy packages, and tier to a limited extent. It will work at a speed which is uneconomical for hand trucks and thus increase the efficiency of ship and wharf. As it carries a larger load than the hand truck, it is not as flexible in sorting and distributing small consign- ments. When it is used in combination with a tiering machine, cargo can be tiered up to whatever height is re- quired. Like the hand truck it does not require any special construction in the wharf shed. Telphers. - - The great advantage of a telpher system is that it- serves every cubic foot of space in a shed, thus in- creasing the storage capacity by high, tiering. It also decreases the amount of deck space required for passage- ways for trucks which operate on the deck. It can load and unload heavy packages from drays and cars. It .can, by means of travelling loops extending over the decks of vessels, hoist directly in and out of the ships and can transport goods directly from a vessel to a warehouse on shore. It has a special advantage where it is possible to transfer freight directly between car and vessel. It does not require depressed tracks nor does it require frequent shifting of cars, as it costs little more, within reasonable limits, to transport a load a long distance horizontally at high speed than a CARGO-HANDLING MACHINERY 225 short one. In fact, it is a universal tool which can perform all the operations of freight handling on a wharf. It has the disadvantage, however, of requiring a building of special height, extra strength in the posts or columns, extra founda- tions, and, on wide piers, extra long spans in the roof, together with the necessary girders, tracks, switches and movable bridges, which entail large outlays of capital and increase of fixed charges. The rolling stock is some- what cheaper than an equivalent number of motor trucks, as no storage batteries are required. The telpher system cannot be applied to sheds of ordinary height without sacrificing the high tiering which is one of its chief ad- vantages. In a design for a pier 1100 feet long and 150 feet wide, to be equipped with a telpher system, the estimated increase in the cost of the pier and shed due to extra height and weight of shed, a roof with three rows of posts instead of four, heavier foundations, etc., was about 5 or 6% and the cost of the equipment, which included overhead tracks, electrical equipment, 6 travelling bridges with gliding switches, 16 main track switches, and 4 trains, each con- sisting of one tractor and 3 carriers, was estimated at over $50,000. Such a large initial outlay of capital is a great obstacle to the introduction of this system, especially where the amount of traffic cannot be definitely estimated. While this system is ideal from a mechanical standpoint, it has not had enough applications to prove whether it can be made more economical than hand or motor trucks. Horse Trucks. For long-distance transportation, such as that between a pier shed and a warehouse on shore averaging from 1000 to 1500 feet, the motor truck has to compete with trucks hauled by horses or mules. These are arranged so that the horse is easily shifted from one truck to another, so that the horse and driver do not stand idle during the unloading of the trucks. These are more economical than hand trucks for this purpose and are 226 WHARVES AND PIERS governed by about the same conditions. Motor trucks for this purpose may carry the load or may be arranged as tractors to pull a separate truck. It is improbable that at present prices they can show superior economy to the horse as a tractor except for longer distances than those mentioned above, where their speed will have a large in- fluence. A motor truck carrying a crate or flat board, which can be filled in the vessel, picked up by the motor truck from the deck of the pier and left at the warehouse to be unloaded while the truck is making another trip, Fig. 154. Horse Truck for use between Piers and Warehouses, Brooklyn, N. Y. would probably show the best results. Some such scheme could, however, also be applied to the horse-drawn truck, and it is doubtful if the superior speed of the motor truck for this service can compensate for the high fixed charges, except where they can be operated with a much higher load factor than is usual. Direct Transfer between Cars and Ships. A very considerable saving in the cost of handling freight could be made if it were possible to transfer direct between ships and railroad cars. The small percentage of freight which it is possible to handle in this manner is evidenced by the location and number of tracks on the piers in this country. CARGO-HANDLING MACHINERY 227 It is essential, if a large percentage of the freight on a given wharf is transferred directly between cars and ships, to have two or more tracks on the edge of the wharf. Such installations, with the exception of the case in New York mentioned in the previous chapter, are very rare in this country, but common abroad. unics i '-lOPib* transverse rile DentsSLfoC. All Piles H'diom. & from " Transverse Bents 20'CtoC. Transverse Column Bents.20C.toC. butt. At except those under column foundations art in fwo rows A-CONCRETE CROSS-WALL Transverse Pile L Transverse Colur, TYPE B - EARTH FILL ON PLATFORM Substructure designed for a tw&deck pier Pile Bents') --lOPiles, ' 9Piles 10'CtoC. TYPE C - SOLID EARTH FILL TIMBER PILES "Pi!e'Bents.5ttoC ALTERNATE BID -SOLID EARTH FILL CONCRETE PILES IttffConc Seams, \ | I Cast-steet r6'ConcrefeSlob ^Bollard 9 Piles TYPE -COMBINED TIMBER AND CONCRETE TYPE E - CONCRETE CROSS - BEAM Fig. 155. Comparative Designs for Piers, Philadelphia, Pa. APPENDIX COST OF WALLS, PIERS, SHEDS, ETC. WALLS THE cost per linear foot of the following walls on the New York Barge Cana) are based on the unit contract prices and on quan- tities estimated from the drawings. They do not include excava- tion or filling behind the wall. They are all designed for 12 feet of water except those at Buffalo and Oswego, which were in water 23 feet deep, and at Gowanus Bay, which provided for 17 feet at low tide. In the unit prices will be found the comparative costs of wooden piles, concrete piles, steel-sheet piles and concrete sheet piles which are useful in estimating the comparative costs of piers as well as walls. N. Y. BARGE CANAL AMSTERDAM: TIMBER CRIB AND CONCRETE. SIMILAR TO FIG. 12 Quantity Measure Item Price Amount 68.3 Lin. ft. Round timber $ .30 $20.49 3.14 Cu. yd. Stone filling 1.75 5.50 2.44 Cu. yd. Second-class concrete 7.90 19.28 .38 Lb. Structural steel .05 .02 1.0 Lin. ft. Mall. C. I. nosing 1.00 1.00 4.46 Lb. Iron castings plain .035 .16 Total per lin. ft. $46.45 230 APPENDIX N. Y. BARGE CANAL FT. EDWARD: TIMBER CRIB AND CONCRETE Quantity Measure Item Price Amount .136 M. ft. B. M. Sawed lumber $50.00 $6.80 59.7 Lin. ft. Round timber .20 11.94 5.1 Cu. yd. Stone filling 1.60 8.16 .015 Pile Mooring piles 8.00 .12 1.17 Cu. yd. Second class concrete 6.90 8.07 1.00 Lin. ft. Mall. C. I. nosing 1.00 1.00 .3 Fastening Fender fastenings 1.00 .30 Total per lin. ft, $36.39 This wall was similar to that at Amsterdam, except that the crib was 3 feet higher and the concrete 5 feet lower. It included two longitudinal strips of wooden fenders. N. Y. BARGE CANAL BUFFALO: SAWED TIMBER CRIB AND CONCRETE. FIG. 15 Quantity Measure Item Price Amount .007 M. ft. B. M. Sheeting and bracing $40.00 $0.28 1.0 Cu. yd. Lining 1.25 1.25 2.0 Cu. yd. Ballast 1.50 3.00 .740 M. ft. B. M. Sawed lumber 50.00 37.00 12.31 Cu. yd. Stone filling .40 - 4.92 .633 Cu. yd. Block con., sec. class 9.00 5.70 .9 Cu. yd. Second-class concrete 7.25 6.52 50.0 Lb. Structural steel .05 2.50 1.0 Lin. ft. Mall. C. I. nosing 1.25 1.25 6.0 Lb. Iron castings plain .04 .24 .4 Each Fender fastenings 1.20 .48 Total per lin. ft. $63. 14 APPENDIX 231 N. Y. BARGE CANAL OSWEGO: SAWED TIMBER CRIB AND CONCRETE FIG. 16 Quantity Measure Item Price Amount 1.06 Cu. yd. Ballast $1.75 $1.86 1.100 M. ft. B. M. Sawed lumber 47.00 51.70 11.68 Cu. yd. Stone filling .75 8.76 .6 Cu. yd. Block concrete 9.00 5.40 .98 Cu. yd. Second-class concrete 7.50 7.35 203.0 Lb. Structural steel .03i 6.60 1.0 Lin. ft. Mall. C. I. nosing 1.20 1.20 .5 Each Fender fastenings 1.10 .55 5.0 Lb. Iron castings plain .05 .25 Total per lin. ft. $83.67 N. Y. BARGE CANAL SCHENECTADY: CONCRETE RELIEVING PLATFORM. FIG. 39 Quantity Measure Item Price Amount .024 M. ft. B. M. Sawed lumber, fenders, etc. $50.00 $1.20 44.8 Lin. ft. Foundation piles .25 11.20 .1 Pile Fender piles 10.00 1.00 1.40 Cu. yd. Second-class concrete 8.00 11.20 .20 Cu. yd. First-class rein, concrete 15.00 3.00 5.35 Cu. yd. Third-class riprap 3.00 16.05 5.8 Lb. Structural steel .05 .29 52.3 Lb. Metal reinforcement .035 1.83 4.7 Lb. Iron castings plain .035 .16 1.0 Lin. ft. Metal wall protection .25 .25 Total per lin. ft. $46. 18 This wall as built had timber piles substituted for the concrete piles shown in the illustration. There were some other variations. 232 APPENDIX N. Y. BARGE CANAL WHITEHALL: TIMBER RELIEVING PLATFORM. FIG. 40 Quantity Measure Item Price Amount .222 M. Ft. B. M. Sawed lumber $55.00 $12.21 33.6 Lin. ft. Foundation piles .35 11.76 .1 Each Fender piles 11.00 1.10 1.1 Cu. yd. Second-class concrete 8.00 8.80 4.3 Cu. yd. Second-class riprap 3.50 15.05 6.0 Lb. Structural steel .06 .36 4.59 Lb. Iron castings .04 .18 Total per lin. ft. $49.46 N. Y. BARGE CANAL ROME: STEEL-SHEET PILE. FIG. 63 Quantity Measure Item Price Amount .042 M. ft. B. M. Sawed lumber $60.00 $2.52 5.71 Lin. ft. Anchor piles .30 1.71 .143 Pile Fender piles 13.50 1.93 22.3 Lin. ft. Steel-sheet piling 1.20 26.76 .02 Cu. yd. Second-class concrete 8.00 .16 .407 Cu. yd. Reinforced concrete 15.00 6.10 77.0 Lb. Structural steel .05 3.85 24.0 Lb. Metal reinforcement .04 .96 2.0 Lb. Wrought iron .10 .20 8.0 Lb. Iron castings plain .05 .40 1.0 Lin. ft. Metal wall protection .25 .25 Total per lin. ft. $44.84 APPENDIX 233 N. Y. BARGE CANAL ITHACA: CONCRETE SHEET PILE. SIMILAR TO FIG. 65 Quantity Measure Item Price Amount .025 M. ft. B. M. Sawed lumber $50.00 $1.25 .11 Pile Fender piles 11.00 1.21 .013 Pile Mooring piles 8.00 .10 .57 Cu. yd. Reinforced concrete 14.00 7.98 46.0 Lb. Metal reinforcement .04 1.84 6.0 Lb. Structural steel .06 .36 11.0 Lin. ft. Rein, concrete sheet piles 1.40 15.40 .8 Lin. ft. Rein, concrete square piles 1.25 1.00 1.28 Lin. ft. Rein, concrete round piles 1.50 1.92 1.0 Lin. ft. Metal wall protection .25 .25 Total per lin. ft. $31.31 N. Y. BARGE CANAL ALBANY: CONCRETE SHEET PILE. FIG. 65 Quantity Measure Item Price Amount .086 M. ft. B. M. Sawed lumber $60.00 $5.16 1.12 Cu. yd. Reinforced concrete 14.00 15.68 5.4 Lb. Structural steel .05 .27 184.2 Lb. Metal reinforcement .035 6.45 4.6 Lb. Iron castings, plain .04 .18 11.5 Lin. ft. Rein, concrete sheet piles 1.45 16.68 5.06 Lin. ft. Rein, concrete square piles 1.25 6.32 2.0 Lin. ft. Rein, concrete round piles 1.75 3.50 1.0 Lin. ft. Metal wall protection .30 .30 .31 Fastening Fender fastenings 1.00 .31 .4 Pile Anchoring rein. con. piles to rock 7.20 2.88 Total per lin. ft. $57.73 The top of the Albany wall was 13 feet above mean water sur- face and that of the Ithaca wall only 3i feet. 234 APPENDIX N. Y. BARGE CANAL GOWANUS BAY, BROOKLYN: TIMBER RELIEVING PLATFORM. FIG. 31 Quantity Measure Item Price Amount .192 M. ft. B. M. Sawed lumber $48.60 $9.33 66.54 Lin. ft. * Foundation piles .27 17.96 .092 Each Fender piles 10.60 .98 1.27 Cu. yd. Concrete 6.25 7.94 19.6 Cu. yd. Riprap .72 14.11 8.5 Lb. Wt. iron and steel .035 .30 2.5 Lb. Cast iron .03 .08 Total per lin. ft. $50.70 BULKHEAD WALL DEPARTMENT OF DOCKS, NEW YORK Type Fig. Cost per lin. ft. Depth of water (Min. $166.89) Rock bottom 20 ] Max. 313. 83 > About 36 feet at low tide (Av. 260.00) (Min. 198.42) Hard bottom 21 < Max. 269. 21 > About 13 feet at low tide 'Av. 238.00) (Min. 217.28) Deep Mud, 1876 44 ] Max. 392. 27 [ About 13 feet at low tide (Av. 288.00) Deep mud, 1899 47 Av. 278.50 About 13 feet at low tide Includes dredging, but does not include filling and other inci- dental work. Cost per Linear Foot of Principal Items Item Rock bottom type Hard or firm bottom type Relieving-platform type Min. Max. Av. Min. Max. Av. Min. Max. Av. Dredging $ 6.60 4.50 156 '.66 $107.00 12.50 309 .'66 $30.00 10.40 254.66 $11.00 12.50 49.00 125.00 $44.00 19.50 62.00 133.00 $32.00 16.00 56.50 129.50 $13.00 24.00 72.00 88.00 $62.00 84.00 139.00 139.00 $30.00 44.00 89.00 109.00 Riprap and cobble Piling and timber work . . . Concrete and granite * Measured in place after cutting off. This price was considered very low. The engineer's estimate was 32^. The excavation for this wall cost $. 185 per cu. yd., scow measure, and the pumped filling $. 125 per cu. yd. bank measure. APPENDIX 235 ITEMIZED COST PER LINEAR FOOT OF A TYPICAL SECTION OF THE WALL OF 1876. FIG. 44 Dredging $32. 41 Riprap and cobble 60. 61 Piling and timber work: Vertical piling $47. 40 Bracing piles 6. 88 Binding frames 9. 32 Sawing off piles 4. 76 Longitudinal caps 5. 12 Transverse caps 8. 37 Decking 2. 74 Backing log in place .74 $85.33 Masonry: Concrete blocks: Fabrication $23. 89 Setting 9.35 Filling chain-holes . 1 . 64 $34.88 Granite: Facing $39. 25 Coping 10.91 Pointing 1 . 34 $51.50 Concrete backing 23. 38 $109.76 Total for retaining wall proper $288. 11 General charges: Examination of the river bottom $ . 05 Removal of old wall 18. 27 Filling in and grading 10. 19 Temporary paved approach to Pier No. 19 1.19 Temporary tool house, fences and plumbing .07 Levels on an examination of the wall .14 Paving 62. 20 $92.11 Total cost of improvement $380. 22 Average Unit Costs Concrete blocks ready to ship per cu. yd $7. 44 Setting concrete blocks per lin. foot of wall 38. 00 Bag concrete foundation, deep rock type per lin. ft 48. 30 236 APPENDIX CONCRETE CAISSON WALL WELLAND SHIP CANAL. FIG. 29 Caissons, 111 feet long cost, $11,000 each in place or $99.09 per lin. ft. Concrete wall on top of caissons cost 4. 50 per lin. ft Total cost of wall exclusive of filling of caissons and be- hind wall $103. 59 If filling of caissons cost 25 per cu. yd., the total cost would be $112.00 per lin. ft. It is stated that the contract prices for this work were very low and that 25% should be added in estimating the cost of similar work. This would make the cost for the wall, including filling of caissons, $140 per lin. ft. The depth of water is about 34 ft. WALLABOUT BASIN, BROOKLYN, N. Y. TIMBER RELIEVING PLATFORM WITH WOODEN SHEET PILING. FIG. 34 Cost per linear foot $80. 00 STANDARD CRIB WALL, DEPARTMENT OF DOCKS, NEW YORK. FIG. 10 This wall costs about 8^ a cubic foot when riprap is 50?f a cubic yard. This would make the wall shown in Fig. 10, cost about $150 per linear foot for 40 feet of water at low tide. CLEVELAND ORE DOCK CONCRETE AND SHEET PILE. FIG. 54 This patented wall is said to have cost, per linear foot $28. 40. SAVANNAH, GA . INCLINED CONCRETE PLATFORM. FIG. 41 Cost per linear foot $50. 00 A similar wall designed for Baltimore with reinforced concrete piles was estimated to cost about the same as that at Savannah. APPENDIX 237 PIERS Locality Fig. Type of construction Cost per sq. ft. New York, N.Y. 1 All wood $1.00 for single pile row portion $2.50 for double pile row portion San Francisco Clusters of three timber piles in cylinder of plain cr } re- inforced concrete; timber decks Same as preceeding except caps are of steel I beams Single pil:s encased in plain or reinforced concrete; timber decks; steel I beam stringers All wood; creosoted piles $1.00 $1.50 $1.50 to $2.40 $.80 to $1.00 33d St. Brooklyn, N. Y. 70 1616' X 150' for one-story shed. Wooden piles; wooden caps; concrete deck slab; asphalt pavement; no side caps $0.97 35th St. Brooklyn, N. Y. 1740' X 175' Wooden piles; wooden caps; concrete deck; slab wooden side caps $1.08 29th St. Brooklyn, N. Y. 1199' X 80' Wooden piles; wooden caps; concrete deck slab; wooden side caps; as- phalt pavement; no sewer $1.21 30th St. Brooklyn, N. Y. 1134' X 125' Same as preceding $1.19 238 APPENDIX PIERS Continued Locality Fig. Type of construction Cost per sq. ft. Philadelphia: Piers 38 and 40 tentative bids for comparison of costs. Riprap added and other corrections made to bring all on same basis for comparison 155 551' X 180' for two-story sheds. Type A. Wooden piles; con- crete cross walls and deck Type B. Wooden pile platform supporting concrete walls and earth fill Type C. Solid fill Alternate. Concrete piles Type D. Wooden piles and caps; concrete deck slab Type E. Wooden piles; con- crete posts, cross beams and deck $2.87 3.07 3.02 3.32 2.43 2.51 New York, Pier New No. 1 Concrete cross walls on rock bottom; concrete arches 14.00 New York, Pier A Concrete cross walls on rock- bottDm; steel girders, concrete arches 11.60 Bocas del Toro, Panama 77 Concrete protected, wooden piles; concrete deck beams; concrete slab 2.13 Brunswick, Ga. 81 Concrete piles; wooden caps, bracing and deck 1.40 Charleston, S. C. Concrete piles; wooden caps, bracing and deck 2.60 Oakland, Cal. 83 Concrete piles; concrete beams and deck $3.25 Halifax Pier 2, 1. C. R. 84 Concrete piles, beams and deck 2.89 Puget Sound Navy-yard, Washington, Pier 8 Concrete columns, steel deck- beams, concrete deck-slab 3.32 San Diego, Cal. 130'x800' Concrete columns, single wooden pile under each column; steel beams cased in concrete; concrete deck 3.36 Olongapo, P. I. 88 Concrete columns; steel deck- beams; concrete deck-slab 2.60 Balboa, Canal Zone 90 Concrete columns, beams and deck 3.28 APPENDIX 239 UNIT PRICES IN TENTATIVE BIDS FOR PHILADELPHIA PIERS 38 AND 40 1913-14 FIG. 75 (All prices are for materials in place in the work) Types "A", and' "B"