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This proof is sent to you for discussion only, and on the express understanding that it is not to be used for any other purpose what- ever. — (See Sec. 47 q/ the ConitituHon). ^anadiaij ^ocietij of ^ioil Engineers. INCORPORATED 1887. TRANSACTIONS. ^f.B — This Society, as a body, does not hold itself responsible for the facts and opinions stated in any of its publications. BUILDING IIAILWA^S ACROSS PEAT HOGS OR SWAMPS. By I). A. Stewaut, M. Can. Soo. C. E. In some parts of Canada lari;e areas of peal boi^s or .swamps are mot with ; and when iocatini; lines for riiilwjya, the engineer frei]uently has to carry the line over these, or avoid them by taking a line objec- tionable in other wayn. and in some oases it may be impossiijle to avoid them altogether. The following observations may be helpful to some engineer who may have tj handle such work without iiaving had pre- vious experience in ih.it way. In building railways over such ground, the method of construction will, in most eases, either bj to form a raft of some kind on which the weight of the track and trains will 1 s it were, floated over the yield- ing mass beneath, or to fill in hard muteiial until a solid bank is formed from the bottom of tiie >wamp upwards. The use of timber trestles, being intended usually iis only a temporary expedient, need not be con- sidered here. If the swamp is at all deep the plan of filling in is both expensive an^' uncertain, so tliat the tirst method should be adopted whenever practicable, which will be the case almost always when the grade line can be kept down close to the surface of the swamp. When the swamp can be drained to a depth of from two to five feet, the cheapest and most convenient plan will ^be to cut side ditches on both sides of the road bed, with such off take drains as may be needed to take the water out of the side ditches, and to use the material taken out of the side ditches to make a light <'mbimkment. The body of partially dried peat between the side ditches is then sufficient to carry the liuht embankment with the track and trains In this way railways have been carried over swamps so deep and soft that one man could push a pole into the muck lor twenty feet or more, and pull it out again. If the covorod on the sidcH :is well as nn the top with sand "i- graved us sotm as pussiblo after tlic tr.irk is laid, to keep tiiem from t;ikins fire iind biirninj,' away, ihc muck banks should not be made more than twelve feet wide on top I'ni- a standard' ,;,'ange railway, so tiiat the (|uan- tiiy ^ot ficm si.le ditches of the size mentioned above' will be ample to fiirm the roadbed. It is usual to make the sides of the ditclies vertical or nearly so, and they will stand in this way for many ytars without iiiliing in, but it would be as wdi, if oul.s lor the sake of ippearaiieo, to have theiri slopeii. U will prove true eoonouiy in the long run to be liberal in the matter olort-take ditches. The light moss from tlic top of the dilehes and roots and sticks found among the muck are fre- nt into the bank, they should he burned for the sake of appearance. The berms .shonld not be left very wide, one and a half times the depth of the side diteh plus five I'eet, measured from the slope stake to the inside edge of the bottom of the ditch, woidd be a good rule in most eases, uidess allowance is being made for a second track, in which case the width of the roadbed should be added on one side to the above. The objection to-wide berms is that the wei-lit of tlic bank causes the inner side of the berm to sink lower than the outside, thus forming a depression along the foot ol the slope in which water collects, forming unsightly pools and softening tlie banks. As the surfaces of such swamps are either level or slope gently, a sur- face line will always give easy grades; and the grade lino should as nearly as possible be a line parallel to the surface of the swiiinj), thus making the side ditches of uuilorm size. The swamp will settle as it is drained, and the bank as it becomes consolidated, but in ordinary eases no attempt should be made to raise them up to the original profile grades, the cost will be greater than any gain, and the additional weight may even cause the bank to brc.k through the crust. When the swamj) is too wet to allow a bank to be made in this way, and drainage cannot be got, and the grade line can be k.-pt close to the ground, a raft may be made of logs or brush, or both, with enough peat on top tti hold the track and keep the ballast from sifting through. In this case it would be better to take the peat or muck from some dis- tance outside the ('nds of the legs, as by cutting the skin of the swamp clo.se to the road its bearing power would be dimini.shed. One tier of logs shonld bo laid lengthways of the road, to help to diminish the un- dulations (if the track under trains. The cross logs should be as Ion" as can he conveniently got and handled, so as to distribute the weight ovitr as wide an area as po.ssible , but then' is no gain in putting down more than two or three tiers of logs, as tlie weight will tend to sink the raft down, and the object is to carry the track over the crust of the swamp without bceaking through. But when the cru>l of a soft swamp has been broken, and the hole has to be filled up, if timber is plentiful and convenient, it may be used simply as filling, and will have a cer- tain advantage from its not being softened and ilissipated by the water as earth or sand wimld he, and in deep bogs may form a sub- merged rait capable of carrying ilu? required load. .Sawdust has been used with success for filling low trestles on the Wabigoou section of the Western division of the Canadian Pacific Railway, both in eases where the banks had broken through the sur- face and where greit cjuantities of gravel had been put, in, but without bringing the bank as high as the original surface of the swamp, and also in one case wliere no other fillinj- had been used and the .surface \mi\ not been broken. In this case the trestle was about sis hundred feet long and eight feet high, and soundings had bacn taken to a depth ol'sixty Ibet without 6ndiiig firm bottom. The sawduat was spread out to slopes of three to one to distribute the weight, and track ties iwi!ivc feet long were used. Both top and slopes were covered with six inches if gravel. The sawdust settled unequally, and a wutohnjao was kept on for four months, iiud the track lifted and tamped oocasionally, but after that t'r.-'e there was no farther trouble. The eulveiis in such swamps should be made of wood, the banks will usually be too low for ma.sonry culverts, and the foundattons would be very expen.xive, pipes either of cast ir,,n orearth.-nware would he liable to be broken or parted at the jointj by the movements of the soil, while wood, if properly put together, would yield to aueh move- ments without injury. Being always damp, or at least the lower pitrts of them, they would last well, espocially if made of cedar, and the banks being low, they could easily be replaced at any time. The chief objection to rail\y.iys built in this way is the exoessivo creeping of the rails, caused by the undulations of the track un ler trains. To remedy this the use of cinder ballast and ties twelve feet long was introduced on the Western division of the Canadian PaciUc Railway by Mr. Whyto, the general superintendent, and these have been succe.sslul to a considerable degree. The evil might be still further lessened by the use of .stiffer rails. When the bog is too soft to carry any embankment, however light or the grade line cannot bo kept near i,..e surfaco, there will usually bo no other way than to till in firm material until a solid bank is formed from the bottom up. In making estimates for this, not only should the bottom of the fill be assumed to be at the bottom of the soft material instead of the surface, but large adilitions should be made to the quantities so calculated, because the .soft material, being displaced by th2 filling, will .slip out sideways and carry portions of the latter with it . In many cases the division between the bog and the underlying material will not be distinct, but the one will merge gradually into the other, and in such cases the quantities of filling required will be corres^-ondingly uncertain. The worst cases are usually where the soft muck is underlaid by soft and slippery clay. It is a common practice to get the track over such pi ices by using timber trestles, leaving the permanent work to be donclater; but '.fhen this is done, careful sound- ings should be taken and the method of doing the pernianoiit work and its probable cost fully considered. This nii,'ht not seldom result in the adoption of some other line, or a chacge of grades, which though more costly iu the first place would be very much cheaper in the long run iia well as safer. It should be kept in mind that the uUing of these tres- ties is often lift until the traffic over the road is large, then not only will the work of filling be delayed by the traffic, but the latter will also be hindered or possibly interrupted for days together by the accidents which are almost sure to happen in the course of filling high trestles over soft ground, in spite of all the care and precautions that can be taken, and in addition to these delays there will be the cost of main- taining the trestles in a passable condition, perhaps even of rebuilding them. If all these things were taken into account, it would often be found to be really cheaper to take heavy rock work than to make high fills through these bogs ; this will be understood when it is borne in mind that rock increases in bulk when broken up, that it will not take flatter slopes for being wet, as is the case with earth filling, and will not be .so readily carried away by the movement of the soft material as would sand or gravel. Besides, in many cases a rock embankment would avoid the need tor a culvert. But when it has been decided to cross any snoh soft ground at a high level by means of trestle work, to be filled in afterwards, the per. 3 raanont structure, if any roquirod for the passaj^e of water, slioiild be -o witli its proper location ai.d construction aftorwar.js. in noiilcct of tliis it often Imp- pena Iha', the rim of firm uronnn nt the ,.d;;c of the bo^' is filled over by the niaierial from euitin-;.* on both sides, miilciii;;- the foundations of the permanent si ruetun^ a matter of great difficulty un.! expense. «uch ho-s are often buiin.hMl l,y loelcy fid-es; ;.nd wiioii these are sO shaped that tunnels la,- tlio passnue of the wator "an I..' driven tliroujjh them without beinji too long, tliey uiay be cheaper as well a- more secure than ma>uiiry euiv'cri;s ; tiic enniparison will drp.^nd ,.|iieHy on tho respective len-tlis of the culvert and the tunn.l and the size of the openin- required. lUit tiiis (|U(stion should be decided before the site of the proposed tunnel is cov.Ted over, the tunnel sliould be located, test pits duit or borings made, and tlic r.'sults left on record, otherwiso it may be difficult afterwards to ascertain whether the rock is suitable fir a tnnnel or not. If a stream tunnel is not possible or suitable, the culvert will, of enurse, ir at all josMbJe, bo placed on Hrm .irround,' beyond any danjrer of movement ; il this is not possible, it would per'. haps bn b.'tter to build it "tron-ly of wood, makiiii;; it so lar-e that a pipe or brick culvert lar^'i' eiioiij,di to earry i he water can be built itiside it after the bank lias done srttlin,'. Som.'linies a platform of |oi.'s is used under ilie fill ; but il the fill i. at all heavy, this is not of any use as it will hebioken uporsunk, andin any case will count (miy as so uiucli filluiL', when it will seldom hi' as cheap as u'ravel, and will ipake it more difficult to keep the trestle in shajie. If clean, coarse urav fill sh.jies steeply, if tho fillino j., ploui:hed off iinit'ormiy over the leiiglii (d' the tresti", it is apt to .slide towards the middle ot the trestle, .and so crowd the bents ; this nuiy be prevented to sowe c.Ntcnt by filling from the middle towards both ends. In such w.ay.s, by cairiul watching and distribution of the fillinir, much may be done to preseiTo the tre.~tle in a pa.ssable condition, butiu i;ll bad eases, a bridge crew - .mhl be kept on the work, and plenty of material lor repairs should be kejit on the ground.' It will bo an .■Klvantage to have as many as possible of the men working at the all boarded i lo.s.. by, and arrangements shoul.l be made so tha't additional men can lie ^ot and aeconuuodated, and ample material and tools procured at short notice in case of craoraeney. The objections to undertaking heavy Hlls across soft bogs, and the precautions that should betaken when such work has lo be done, noted above, apply cvn mor.. strongly to t!,e case of ponds or lakes' with soft and muddy bntton.s. wldch may be considered as bogs with their surfaces covered to a greater or less depth with water. Th^e most valiucblo assistance the engineer can have will be a few good men who have had some experience on similar w(u-k. 4