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(All rights reserved. 
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 .onadiaij ^ociety of ^ioil (^ii^in«ei'5, 
 INCOUruUATEl) ISSl. 
 
 TRANSACTIONS. 
 
 N.B— This Society, us a body, docs not hold itself responsible for the facts 
 and opinions stated in any of its publieations. 
 
 THE CONSTRUCTION OP A SMALL TUNNEL. 
 By J. 0. G. Keruv, \. M. Cax.Soc.C.E. 
 To be read Thnrsdaij, lUtth March. 1894. 
 
 INTRO miCTION. 
 
 Tho West Vnro;inia & Pittsburgh R.R., a feeder of the H. & O. 
 system, \v:is built to open up the Sparsely settled and formerly inaeeessible 
 counties of Central West Vi.-^inia. Tr.poi?raphieally, these counties 
 show series ol' heavy narrow parallel ridj^es with deep .iividing valleys ; 
 thes(! ridiies run roughly east and west, and are some of the many chains 
 of mountains eomprisiim the ;jreat AUe-rhany range ; the valleys are 
 drained by tributaries of the Great Kartiiwha lliver, one of the main 
 feeders of the (Jhio. The slopes of these ridges arc short and rough, 
 and tho line in its general course due southward cut directly acros'* 
 them, necessit;iting a difficult location with heavy grades aud expensive 
 work. At the divide between tiie lattle Kanawha and Elk River 
 valleys, it was found impossible to locate over tlie summit while main- 
 taining the desired maximum grade ol 1.5 per lOO.and the tunnel whose 
 construction is <l-. scribed in this p.ij.er was needed to pass this point. 
 
 'L'he railroad was built by the West Virginia Improvement Co., of 
 which Mr. .l.A Fickinger was Chief Knuincer and Manager, aud the 
 contract foi this work wa.s let in January, 1891, to T. J. St€er8 & Co. 
 of Weston, W.Va. 
 
 LOCATION. 
 
 As finally located, the lim- passes through the north approach out and 
 into the tuimel on a 7 = :'.0" curve, the V.'W of which lies some 40 ft. 
 beyond the portal ; the remainder ol the luimel and the south approach 
 cut arc on the tangent to this curve. The tuiiiud is built on a 0.25 
 per 100 grade falling to the southward, and is on the nummit between 
 two 1.50 per 100 grades. The portals were laid out so that the cut on 
 centre Unc at the head ol the portal slope would be 50 feet, the distance 
 between them being 624 foot. 
 
 M.\^TERIAL. 
 
 The material through which the tunnel \s as driven was a soft blue 
 cliiy shale, nearly dry. and showing little stratiUcation. This shale rap- 
 idly <lisintegrate(l on exposure to the air, and tunneling- through it with- 
 out timbering would iiave been dangerous if not impossible. The company 
 not being prepared to line the tunnel throughout with ma.sonry at tho 
 time of eonstruetion, il was necessary to use a .system of timbering 
 amply strong for several year,-;' service and largi! enough to contain the 
 masonry wlien it should be built. The unusually large excavation section 
 Bhown in Fig 1 (18.77 cub. yds. per lin. ft.) was rendered necessary 
 by this double lining. The shale was overlaid wi'.h beds of heavy and 
 Strong sandstone dii)pinu; slightly U)wurd the north and so low that 
 near the north portal souu; of the sandstone had to bo blown down to 
 make room for the timbering. 
 
CmJ 
 
 "^^^mw^^w^- 
 
 
 METHOD K\V EXCAVATION. 
 
 When the contractors had lull forces, t.lu' cxcavaiion w:is curriud on 
 by day and niu-ht shifts, workiii}; ten hours I'licli from both ends of the 
 tuuni'l. It was but raiily, however, thiit full forces wen ■ cuiployed, as 
 th(^ iidji'Cent gradiuf; w:i,s mort^ backward than the tunnel and the men 
 were drawn otf to it. The excavation was all done by h md work, no 
 special tunnel machinery beins^- employed, and it was conducted on the 
 general principle *hat nothing is so expensive in tunneling as a cave-in 
 
 HEADING. 
 
 The shifts were divided into heading and bench giuigs, the foreman 
 of the bench gang being, however, subject to directions from the foreman 
 of the heading. The heading gang consisted of a foreman, 8 miners, G 
 muckers and a " nipper ; " and its work was to excavate the material 
 from the bottom of the wall-plates up (7,70 cub. yds. per lin.ft.) to 
 place the wail-plates in position, to erect the aiehes upon them, and 
 to lag and pack the same. 
 
 Coming back into the heading alto- a blast, the miners first pulled 
 down all dangerous material from the roof, then cleared away enough 
 of the debris of the blast to give themselves working room, and proceeded 
 ■with the drilling. Three sets of holes (two wet and one dry) were 
 usually drilled in the face of the heading ; each set consisting of four 
 holes about 4 ft. deep, the exact placing of each hole depending on the 
 success of the last shot ; twenty-four lin. It. of hole was considered a 
 day's work for two miners. The holes were loaded with from 4 to (i 
 sticks (\ lb,) of dynamite apiece, and fired by battery or fuse, as might 
 be desired j as far as practicable, all blasts were fired at the end of the 
 five hour spells, so that th(! dynamite fumes might dissipat(! during the 
 idle hour ; the average fall from a heading bl:ist was 2,^ ft. 
 
 While the drilling was progressing, the muckers cleaned up the heading, 
 the scaffold car. Figs, 4, 5 and 0, being necessary for this purpo.se. This 
 was a mounted plattbrm, with heighta little lower than the heading floor 
 and with its frame so arranged that dump ears could lun right under it 
 and be loaded through shoots from the platlbnn above. It ran on a 
 special track, and was provided with long detaehed planks which were 
 laid from the platform on to the heading floor, the muck being wheeled 
 down them and dumped through the shoots. The car was provided 
 \fith a small derrick for handling timber, lagging and packing. 
 
fT ..■!■' OF fJ.rir/!7/0/V 
 
 no 5 
 
 ^n(jff7 eroM Arac0 <rf ^.4i^ 
 
 r/fo/rr j-/e y/fT/o// 
 
 
 ■ a»mmA mmaf 
 
 Fig 6 
 
 
 hencii. 
 
 The bench u^&ws ciiii>istc(l (il'a rurfinim. S drilleia, 10 inuckiTs unJ a 
 " uijipcr " ; ;inc.l its work was to cxciivate the iiiaUMiul ii'Uiaiuinu; in the 
 section (11,117 cub. yils. jier lin. i't. ), .to place the plumb posts, and to 
 lag anil pnuic liehinil llieni. 
 
 Alter a beneh blast, tlic whole ,t;aiii;, was put at work cleaning off the 
 rails of the acatrolJ ear tiaek, and pushinii tlii.s up as way was made 
 for it, it beinu' alway>* run baek for safely befnr.' a hla.st. When the 
 sealfold oar was brnunlit far «mioii;j;1i ahead to couiniunicate with the 
 headin<f, the drillers olearnd off [il.iei's for their new set of holes, and 
 weiit to work on tliem. The beneii was shot down in four foot holds, 
 two half-depth blasts beinj;' made for each hold ; each blast consisted 
 of four holes, two beini^ centre holes and two drilled as nearly vertically 
 under the inside edge of the wall-plate as possible ; the charges were 10 
 
sticks of dynamite to an outside liolo and 15 to u centre one. The 
 drillinj; and blastiuj^ of tiie bench though Himplo required »i{illful nian- 
 a!,'(nnt'nt, f'".. points to be i^uavdi^d against being : dani;i;,'e to plumb 
 posts and areli timiters, daniicr of uneovcrinj; too great a length of the 
 wall-plate at a single shot, and complete avoidance o( any interference 
 with tlie progress of the headinj;. 
 
 Tlie muck was taken out to the dump in side-duinperw of about one 
 yd. practical capacity run in trains of iwo, the heading muckers loading 
 one through the seailoid car shoots, while the bench men loaded the 
 other, the bench men having to clean up to the face of the bench before 
 the next blast was ready. Where the rock shot down in largo masses, 
 progress was much aided by the use of stone flats mounted, so that the 
 plattorms were liush with the tops of their wheels, on to which heavy 
 rook could bo barred without blocKlioHng or extra handling. The 
 bench was ke[)i aboui. two wali-plato lengths behind the heading, and 
 made the same average progress. This progress was about 2h h. per 
 shift ; the aciual excavation was made at a rate of 5 ft. per shift, but 
 the time consumed in pointing down odd i>rojectiotis, timbering, lagging 
 and packing being eqii.il to that spent on rough excavation, the pro- 
 gress rate was only 2^ ft. per Bliift. 
 
 PROURKSS OP KXCAVATION. 
 
 The north heading starled under on April 17th, tlio south headin<' 
 being delayed by a heavy approach cut, until .Juno 3rd. No record was 
 kept of the monthly progress, the irregularities of the forces and 
 delays oceasioned i)y lack of timber i-endered all such records valueless. 
 The hoadinys were holed on kSept. 17th, and the bench was finished hy 
 Oct. 15th, the work having been in [n-ogress for just si-^j months. 
 The heading was driven with great care, and no exceptional record was 
 mailo until the night lietore tiie lioliiig, when two gangs drove 20 i't. of 
 heading of lapiJly diminisliing cross-section in a desperate eflort to 
 pierce the 21 feet remaining in the tunnel. The driving of the bench 
 was of course limitid hy the iieading, but after its completion the pick 
 of the lorces wore placed on the bencli, and with gao'^s increased to one 
 foreman, ;i drillers, 12 muckers and nijiper, the rate of progre.ss rose to 
 3J ItiCt per shift, the bench being blown in t'> It, liohls. 
 
 IlirKtCtll.TlKS IN EXCAVATION. 
 
 Ko trouble was experienced with tlie bench anywhere, but the 
 heading was tre((U(mtly in bad ground. At the n* iili portal llie top of 
 the Iieading passed into a .shattered bed oi' sandstone rock, wliieh coulil 
 not be shot down williout disturbing a considerable amount of material 
 on the portid slopo. Here a tl' X S' drift was made under the sand- 
 stone, and the heading c\p:mded to its lull section and timbered at the 
 second wall-plate, and the first wall plate I. ngth was driven outwards 
 the shattered mek being eaught n]i by tinil" rs ns quickly .'is the excav- 
 ation was comiiK'teil, 
 
 As the tunnel grade fell and the sandstone rose to the .southward the 
 heading was soon clear ol' tin! sandstone, wiiieh made an admirable roof 
 for a season. 'L' he .shale had very little adhesion to the sandstone and 
 when the sandstone bed and tin; tunnrl section separau'ii, it soon proved 
 itselt'not sufficiently strong to hold up across the span by (^omint!: down 
 in heavy lidls, which left the bottom of tlic siindstono exposed. The 
 material between the bottom ol the .sandstone and the t^)p of the section 
 was accordingly excavated, until its thickness grew such t'/iat the cost of 
 its renioval bicamc an item of considerable ex|Huiso when it was deter- 
 mined to hold it in place. This material where removed was classified 
 as " fallen material." 
 
 Up to this point the system had been to drive a full hcadin- for a wall- 
 plate length, and then timber it up. This was now chaniieil, and the 
 heading was driven with an ardied longitudinal section hiiviu" full 
 height at the end of the preceding wall-plati'. ,iiid being barely hinh 
 enough at the end ot the new wall-plate to admit of its being ousily 
 
placed. Tho new wall-plate boin;.; in position, fhooxoavation nocowary 
 for each of its imposed iin-hos was iiiii(iti si'paratoly. oacli beiii}; ort'Ctod 
 blockfid and partially packed betdre the excavation for the suciwiliu;; 
 one was coinnu'nofd. Tlie last arch bciiii; up, tho bcadiiiii was au'ain 
 driven I'oiward li)r a now wall-jilaie. Side drifting,' to place the wull- 
 platos, nn which tiie arches were tlicn built as in the inetluul jnst 
 deseribed, was tried, but was almost immediately abandoned as more 
 costly than that motbod. 
 
 It is only just to remark that, (.win;; to thenreat oaro thus taken by 
 the contractors in all doubtlul places, neither fatality nor accidental 
 interruption occurred during the progress of the work. 
 
 TIMIIKU. 
 
 Fid 2 
 
 .•f.r 
 
 
 ^ecr/o/v o/= r^A^/sji/fy/YG 
 
 • 
 
 The system of timbering is shown in Fiji;s. 2 and 3. All timber was of 
 white oak, and was carefully inspected ; all sticks had to be in a thor- 
 oughly sound condition, and arch .segments were rejected if they showed 
 any aigii uf luiigitudiua! cracking or splitting. Tho system of erection 
 was as follows : — 
 
 ft 
 
HXAOINO TIMBIB. 
 
 The heading being ready, a j^air of wall plates were brouj^iit in, and 
 the engineers were soiit for, to superintind the plucing of them. 
 Thisoptriition is* dcscribi'd t'urtlu'r on. 'I'lie wall-plates wore 12" x 14" 
 X l(i' — 0' , and as the tlieon-tieal sprinj;iii,i; ulthe arch wan at the lower 
 side of the wall-pliile, radial Ix'dn were adzed on its upper side, to make 
 bearinj."* lor the arch tinibcr.s ; ttn' wall-jilatcs were jointed by lialviDi; 
 hir a foot at each end, and were made in pairs, right and left, iso that 
 the forward end when in position might alway.s show the lower section 
 of the half-joint, that being a material advaniage in the )ilacing of the 
 plates. Tlie Wall-plates being in jio^ition and securely L'ocked 
 ugain^t outward and downward nioveunMit, the joints were secured by 
 tightening up llic clamps. The detail of these clamps is shown in Fig 
 3. Stitfeniug plauks li'x 11" x 2-0" were placed above and below llio 
 jointed plates, and drawn against tliem by tightening up bolts working 
 througli pairsoftran>ver.-^e straps. Tlu'se bolts and strajis art entirely 
 outside the timber, and comprise all tlie permanent iron in the tunnel. 
 
 //6 7 
 
 cs//r/f//ye ran 7-y/*fS£A' /'^c'^fA 
 
 The arches were erected on the segnu'iit centres shown in Fig. 7. 
 Thearehesareof 12 'sl2 ' timber, in seven se!.;nuiils, the .segments being 
 cut totemplate, and were erected by simply laying each segment in pliice 
 on the centres. The centres were 'Mccted by jciinting tbt.' two segments by 
 the bolts shown in i'ig. 7, and then bloeking np their feet to pro])er 
 position; the long hook shown in tlu! same Fig. was driven into tlie 
 p'eceding arch, and .«erved to hold the frame in position at its proper 
 spacing; the .second system of segment joint tlie/e shown proved the 
 better in practice, being more readily handled. The arch segments 
 being up, they were blocked solidly from the roof against all upward and 
 outward movement, and!" x 1*2 'joiigle-bloeks with K ' shoulders were 
 placed between consecutive arches at each joint. The centres were then 
 withdrawn and the la;;ging coiiimeueed. The lagging was dosedaid in 
 lengths equal to the iireh spicing and the bottom piece bore on the 
 projecting back of the wall-plate. All voids hacik of the lagging were 
 tilled witli broken sandstone brouuht into the tunnel for the purpose, 
 and hand-laid. The use of sandstone was insisted upon bccau.se it 
 was feared that the siiale would doterifrt-ate in timu and yield under 
 pressure if used as packing, thus i^iving the nms.ses above a chance 
 to start moving. The lagging and packing were carried up sim- 
 ultaneously, the packing of llie crown segment being cimijileted from 
 between the next arches ; and the timbering was completed l)y nailing 
 uj) the two lines of l"xt)" lacing plank at each joint. These lacing 
 planks were to [irotect the corners of the segments from blasts, and were 
 torn down after the tunnel was coinjileted. They bad the demerit of 
 hiding the condition of the joint, and were accordingly ondtted in bad 
 ground. 
 
 BENCH TIMBER. 
 
 As the bench was removed, the wall-plates were caught up on the plundi 
 posts, due watch being kept that no length of tlie wall-plates was at any 
 time left without ample support. The posts were underlaid by4"xl2" 
 
 6 
 
 I- 
 I 
 
 ' \ 
 
plank in G feot li'DglliH, iinJ wcdKofi licnrinp upon tlioH' pinnks were 
 driven until tlif pout focik u lull lnaiiiii.' n/aiiiHt tlif Wiill-phitc above. 
 The posts wiru spnc.'.l l.y 2' x 12 ' plunk nt liot luid l,(>n,|. Tiio lau'iiinu 
 and packing Wcii' I'lirricd up .siinullancouHly I'rini tin' floor level, liut it 
 WHH not coMsidcrt'd nccci'tuii)' to kiip thi.s wm k if;:lil up !»n in llie case 
 of the iircli lo^'Kiiiir, and it ol'tcr) (i'li connidfrnbly licliirid, the nhale on 
 .-ueln.ooasionn provinj,' itself aMij)ly srroi j. fo ^t.iiid without sujipoit 
 durinj; the short jteriod of exposure, the rate o|' disintvuratioii beiiii.' 
 very slow in the unehanniii^' atniospheiv of the tunnel. No provision 
 was made in this system for side liini; pressure, and no need of such 
 provisiou waa develojied. 
 
 DIFFICULTIES AND Al.TISWATIONS OF TIMIiKRINO. 
 
 The details of the syiiteni were varied to suit eireunistinices. Tho 
 heavies^ pressure (iinnieJiate and luture) was unticipuleil at ihi portal, 
 and the end wall -plates were aoeordinyly carried h II out, and all the 
 rallied voids between the latij^irm ami the portal sIo|h- filled with timber 
 blocks ; »nd for the first 15 ft. at (he entrance t ' laL',i;inf; was ustid over 
 the areh.und 3 behind the jilnuib posts, these heini.' reduced to 8" and 
 2" respectively for the remainder of the tunnel. The arch and i)luui. 
 post spacinj; was 3 ft. eentre t<» centre : a proposition to maintain the 
 hickness of the lagginj; at the end of the first 45 It. and to inereaso the 
 bib spacing being considered and rejected. 
 
 As described hereafter, the wall-|,liitcs were set narrow, hiuh and 
 canted slightly inwanls, the elfect beiii^' to leave the segment joints open 
 at the back and tight on tho front, so that the joints would take a full 
 bearing when tho pressure canieim and the edj;cs yielded under it. Near 
 the centre of the tunnel it was noticed that the joints of the arches on 
 three wall-plates had opom'd at tluir lower edges indicating heavy 
 downward pressure. The \vall-|ilates were innnediately dapped to recoivo 
 extra arches; these were similar to the existing arelies in every respect, 
 except that one of the end segments was cut off short and wediies were 
 placed between it and the wall ])lale, bv driviiiii whieli the aroh was 
 forced to a lull hearing against the laiiging. Fur two wall-plates alter 
 this occurrence,|seven arcdies wife placed on a wall-plate instead of five • 
 but as the indications of pressure then ceased, the live were a<'ain 
 adopted. 
 
 GRADE AND AI.rO.V.MENT. 
 
 By reason of the gonorarplan of construction necessarily adopted the 
 company had toe.vcavate a large and expensive section ; hut this section 
 wasredujed whoever practicable, and thus the clearance between the 
 systems of lining wasreiluced to a minimum, necessitating very careful 
 placing of the timbering. The wall-plates were the determining nie.n'oers 
 of the timber system, and lliey were, thereli)re, placed by the engineering 
 staff. The plan of operations was as follows : 
 
 Taking advantage of the fact that the main tangent in tho tunnel 
 passed out of the portal at the curved end well within tho section, this 
 lino was established by live hubs, one over (laoh portal, to .servo as baok- 
 8%hts, one on tho summit and one well away from each portal, in such 
 position as to ooiumuad a full view of it. These latter served as 
 instrument stations, and from them the line could be run right into the 
 heading when necessary. No permanent pi'ints were established in the 
 tunnel, the line being always brought up from the o.uside points when 
 required ; the P.T. was established temporarily and the curve run in 
 from the tunnel tangent. 'J'he signal used in the tunnel was a small 
 miner's lamp with a plumb bob hung below the centre of the flame. 
 When the tunnel was smoky, recourse was had (o the gasoline lamps 
 used to light the tunnel. These w.io known as " electric torches " 
 and had a long pendant arm ol gas pipe terminating in a bend and' a 
 small circular nest of burners, the plumb bob being attached to the 
 centre of this nest. <.)n very bad days (i)r seeing, the speediest method 
 was to establish points on the tani;ents as far as could be rcadi!" s^on and 
 then to move the instrument up into the heading and get it into range 
 
with the points. Whon nootlcd, tho liiK^ was in irk.'tl hy n fxjinporury 
 jwiiit Dppositfi thi) forward ends of thts now wull-iliite*, tho position of 
 thi' last wall platohciiiir always tried a.s ii ehi'ck Thr icvrl waMthen H'l 
 up in the hiaclinji, ii.iicii in irk" hoiiij; . .<tHl)liil,rd in eiu' tunin'l, and 
 till! wall plate was nliornulciy xliiflcd in tirade and ali).Minii>nt until both 
 wcro satiHfiotory. A miner's lump, held clofc ti ili. race of tin' fod, 
 provfd siirticient lo iilimrhialc Imili it and tli<> rroHs-liuirs of the 
 instiui'unt. Th. \rall-plal(w wore norniallv hi t ^ i.ai row, 5 high, 
 und canted slightly '..iward.*, thesi' idlowaiicf- l.tdn;.; nia<lc to provide for 
 the unavoidable (.etilaiT'! under ciiiii[(r.>siuii. When the hettdiug was 
 holed, tlie Jiue nnd levels met within \ imh, 
 
 MEAHiritl-lMENT OK KXCA V.VTION. 
 
 At every set of tiudiers a reiiular series of offsett was taki'ii hy tlie 
 inspector from the outside of the frame to th,^ face of th.- roek, four 
 meiisurements heiie.; made Irom each plumli post, one fron. everv ureh 
 joint and one from the centre of eueli aruli segment ; the measmvments 
 of the sets on eaeli wall-plate wen' averaged, and these averajivs were 
 leeorded ;is ilu" uieasiin UH titM.f iliatwall-|i!at leiij;tli and tho area and 
 contents ealeulat( d tlierelrom ; ihf recorded measnremelrts read as if 
 taken from the arch eeutre. The systt-m of measunnient proved verv 
 eonvenieiit ; the step hy step .nethod of excavating and timherie ■ 
 wcmld have si'riously l^auipeivd any other -yst^uu, hut with this the 
 inspector eould always make his meiisurements whenever the excavation 
 was complete and the lindM r IVaine in plaeo, i^nd the lag'.'iag ami 
 packing mii^ht immediately proceed. Any eriiu'in the relative placing of 
 tile timbers would, however, be reproduc, ! in the measureuieiits. These 
 sections were taken as a precautionary in isiir.-, it being specilied that 
 the work would be paid for by theoretical dimensions. 
 
 COST. 
 
 The prices and costs were as ftdlows : 
 
 11,726 Cy. Excavation at; 5f2.S5 $;5;{,Uft.lO 
 
 7i2 Packing 1.75 1,298.50 
 
 Fall'ii Material 1.25 320.00 
 
 Ft. B.M. :JO.OO 0,090.00 
 
 25t) 
 303.000 
 
 (124 lin. ft. of tur.iiel 844,127.';0 
 
 these iigures being contract prices, the acltial cost being probably in 
 the neighbourhood of 8;!5,(I(I0, In I lie aj.prnachcs the pi ices were 
 solid rock, SO ets. )iei- cub. yd. ; loo.-e rock, l(» c(s. ; imd einth, 20 cts. 
 White uak timber was delivered on tlie ground for $15.00 per A!., uuu 
 cost $3.00 for framing. Common labour was worth $1.-15 a day in the 
 tunuel, and the miners were ]i;iid 81.75. 
 
 -M.VNiiNIIY. 
 
 />6<y 
 
 sscr/o/y o/- />r/isoAffiy 
 
._ 
 
 -. 
 
 
 
 U 
 
 , I —I 
 
 fib 3 cr/*7/Tf/^e /-o/t /yf,'?j j/r/tr 
 
 Oil con»Wci'itii» tlio ]i('riii:uiL'ut stiibility i>l the tiiiiiii'l it wart ihouifht 
 tliat ii'any j,'r«iunil inovciiu'iit sliiuilJ cicriir miuIi :ts wiuld biiii}.' heavy 
 pressure upon the linii!;j;, it would Im' in tin' vicinily ol' tin- portals, whih' 
 the tiuibcrinj; wouM decay iiicist r:i|iicliy at tiif ^aiiic plate, ft was 
 tliurrtoru dctt'i'i'iiiii'd t<> put in port 1 Is and In Imilil ilie inasoiiry linini; 
 for tii'ty fi-ot at eaeli end. 'I'lic masonry scctinn is shown in Fij;. H. 
 It was built of ivd sandstiine, very coaiNo in stn'ctmi' anil Will ailapt'.'d 
 to resist the aetioii of h'alid lmsis. TIu' sidcwalls were laid in ennrHt'.-, 
 all litones beiiii; two I'eet m- more t''iek, and the iiottoni courses weie 
 cxtonde 1 into iho tunnel, .s(/ that ihc ends id' the eonises mii;lit b;- racked 
 ort' contiiiuiiusly I'nnij bas' to keyston<', and the wall thus lid't in f;(>od 
 condition I'or bondini; 011 tiic resumption of woik on the lining. The 
 spaces between the |iliiiid) iiosts w re filled wil-li s])awls in mortar. 
 The.se walls were built with a small derriek set np without stilTh'^sor 
 guys, the pin at the toji ol'the p'jst beini; placed in an aujj;er hole bored 
 in the crown seamont of one of the arches; und althon;rh i\w sei;mciir 
 WHS not fastened in any way, the juiut a'ld lairj;in!; friction proved silf- 
 ficieut to overcome any stresses from the ilorrick tendliii; to mo"e the 
 Rcj^ment. The cer.trinir lor the arch is shown in V'vs,. 1>. The centres 
 rested on a '?>" X 12" wall pla.e sujiporti^d by ron^h G" X (J '/ j^wts 
 bcarinj; on a '.\'' X 1-" I'rame sill. The frame sill was carried by 
 wediios working ai;aiiist a 15" X 12'' mud-sill ; the r;uiiie id' these wedges 
 was large, so that the centres wonid be considerably lowered when the 
 wedges were >truek, and the whole section of cen' ' might then be 
 run ahead on 'imall rollers placed on the muJ-sill. With thiit parpo.se 
 in view the post-< we- e set far enough away from the side-walls to clear 
 the quarry face projections of the .-toues, aiid t'.io lirst few pieces of 
 lagging Were omitted on each side of the centre. The section of 
 centring used was about 25 ft lonac, the centres being .spaced 3 ft, 
 centre to centre; the centres were built of three thicknesses of 1" 
 plank breaking joint, and with a minimum depth at joint of 10 inches ; 
 the lagging was li" ^ 4'' laid on the flat ; the consecutive posts were 
 fastened together by irregular dbigonul bracing. The masonry arch 
 was 18" deep, the voussoirs measeviiig 1'- Uj^" on the intrados aud 
 the keystone 1' — 3" ; all joints were \" , ana the voids between the 
 masonry and the timbering were packed with dry sandstone, hand laid, 
 13y reason of the impracticability of the ordinary uiethods of handling 
 stone in the confined space between the lagging of the centres and the 
 timberii.g of the tunnel, special methods had to be resorted to. The 
 method employed was to leave au opening in the crown lagging of 
 
 9 
 
>K/ 
 
 ample size to pass any of the arch stones, above this openiag a piece or 
 two of the tunnel laj^^injr was removed, and an iron bar placed upon the 
 tinib<;r arches. A set of bloiiks were attached to this bar, and with 
 their aid the areii stones were run up till they passed tbnuii^h the 
 lagajiuj;, when they were swung off on to it. The difficulty was to get 
 headway enouuh for tlie blocks to work iu. Gas pipe rollers were 
 placed undu' the stone, and it was run along on its side until it camo 
 opposite its destination. It was then canted upriiiht, theni being room 
 to cant the stone.^ at the joints of the timber arch only, and a single 
 rope was passed rnund it. Si.x men were nccili'd to bring it to place, 
 two hdldiu'j; back on the rope from the opposite side of tne centring, two 
 aiding the slipping of the .stone and iruardini;; its edges from spawling, 
 and two ra;is(nis being below to receive it, throw oil' the rope and set 
 the stone accurately, it requiring decided skill to bring the stone to its 
 right (ilace with an even niortnr bed '.inder it. The keystone was run 
 into plac" dry and grouted. The head-wall of the portal was a rectan- 
 
 FicIO 
 
 £tSy/9 //O/V 
 
 10 
 
 SSCT^OA 
 

 
 j 
 
 1 
 i 
 
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 1 
 
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 ^ — 3 -y^- 1 
 
 j f i 
 
 
 i L 
 
 
 
 Rular block of masonry 25' - 0" V 26' - 0'' X 4' - 0''. It was laid as 
 first class work, and the bond with arch was made by creepera. It was 
 held tliat it was necessary to support these head-walls by buttresses, it 
 beioL!; known that unsupported head-walls in tunnels in tlie same section 
 of the State had lu !i;d under a j;radually increasina; movement uf the 
 material on the portal slope, this movement sometimes only commenoiDg , 
 years after the completion of the work. The buttresses built were 8' 
 _ " X 3' - 0" in plan, and wciro stepped back towards the head-walls 
 commencing at the springing level. 
 
 The prices on this work were $9.00 a cub. yd. for portal masonry, 
 $8.00 for side-walls and S14.00 for arch sheeting. This cost was not 
 included in the tunnel estimate before given, as the work was only par- 
 tially doiie, and becauss the detail of the lining would probably be 
 altered by the employment of a cheaper material when transportation, 
 facilities were obtained. The cost of one portal complete was ; 
 
 76.5cub. yds. portal masonry @ $9.00 6688 50 
 
 6 . 1 arch masonry @ 14.00 85.40 
 
 $773.90 
 
 and the cost per Hn. ft. of lining was : 
 
 Sidewalls 2.57 cub. yds. @$ 8.00 $20.66 
 
 Arch 1.53 @ 14.00 , 21.42 
 
 Packing 1.1? @ 1.75 2.08 
 
 Lining per lin. ft $44.06 
 
 In the estimate before given the cost of excavation, tinbering, etc., 
 was $44,127. 60 for 624 ft., so tliat the total cost per lin. ft. of completed 
 tunnel would be (excluding portals, fallen material, etc.) : 
 
 Excavation $53.55 
 
 Packing 2.08 
 
 Timbering 14.57 
 
 Side-walls 20.56 
 
 Arch 21.42 
 
 Packing..., 2.08 
 
 $114.26 
 The whole work was carried through in a style that was entirely 
 satisfactory to the chief engineer. 6Ir. Jos. N. AUstoii was resident 
 engineer in charge, and the management of the construction was in the 
 hands of Mr. John K. Doughor uf T. J. Steers & Co., and most of the 
 practical points in the system above described were an outcome of his 
 great experience aH a tunnel builder. 
 
 11