The Nilgiri Mountain Railway.” by WALTERJAYES WEIQHTYAN, M

THE INSTITUTION OF CIVIL ENGINEERS.

SESSION 1900-1901.-PART 111.

SECT.1.-MINUTES OF PROCEEDINGS. 19 February, 1901. JAMES MANSERGH, President, in the Chair.

(Paper No. 3230.)

“ The Nilgiri Mountain Railway.” By WALTERJAYES WEIQHTYAN, M. Inst. C.E. THATrack-railways are nowbeyond theexperimental stage is shownby the fact that at the present time there are no less thm eighty of then1 in existence in various parts of the world. Accounts of some of these have appeared in the ‘‘ Proceedings,” 1 but few of them have been described in detail ; and the Author proposes to give in this Paper some particulars of the practical construction of one of the most recently-built lines. Apart from the features of engineering interest which it pos- sesses, the Nilgiri Railway is notable as being the first Abt rack- railway constructed in India, and one of the longest in theworld. It is, moreover, thefirst for which all the plant and material was manufactured in England, andone of the few that use wooden instead of steel sleepers. The line starts from Mettapollium, a terminal station of the Madras Railway in Southern India, and ascends nearly 5,000 feet tothe plateau on theNilgiri Hills, on whichare situated the important towns of Ootacamund, the summer headquarters of the Madras Government, Coonoor and Eotageri, two European settle- ments occupied chiefly by planters and retired officials, and near to which a Government cordite-factory is about to be established, andWellington, the military sanatorium for British troops in South India and Burma. The planters and other European settlers have for many years past agitated for railway communication with the plains; and as

Minutes of Proceedings, Inst. C.E. vol. cxx., pp. 25, 31, 43. [THE INST. C.E. VOL. CXLV.] B

Downloaded by [ UNIVERSITY OF IOWA LIBRARIES] on [11/09/16]. Copyright © ICE Publishing, all rights reserved. 2 WEIGHTMAN ON THE NILGIRI MOUNTAIN BAILWAY. Wnutes of far backas 1874 Mr. Riggenbach visited the locality and sub- mitted proposals for a rack-line on his well-known system; the cost of this scheme (S400,000), however, was prohibitive. Several subsequent attempts atpromotion were made, the most important of which was that of the late Mr. R. Wool!ey, a planter and con- tractor, who formed a company and constructeda considerable portion of the line. Financial difficulties, however, led to liquida- tion,and it was onlyrecently that a new company, having received certain concessions from the Government, wasable to raise the amount required and tocomplete the line. The principal ghat by which the Nilgiri plateaureached, is which is that followed by both the old and new roads, is a short, steep valley about6 miles long, fairly straight, and witha slope varying between 1 in 8 and 1 in 4,with very few side valleys branching from it, in which tomake distance. An adhesion-line would have beenalmost impossible, asnot only would it have been very lengthy and costly, but, owing to the absence of side valleys, it would have been difficult to locate without resorting to reversing- stations, which the then Consulting Engineernot did favour. Every- thing, in fact, seemed to point to the adoption of a short steep line with a gradient approximating to theslope of the valley; the other points req.uiring to be determined were the gauge, gradient, and system. The two former were settled by Government, under the terms of the concession, for reasons given hereafter; and, with regard to the last, after acareful consideration of the relative merits of the Fell central-rail and the Abt rack systems, the latter was decided upon. A plan and section of the railway as constructed are shown in Figs. 1 and 2, Plate 1, from which it will be seen that the line is 162 miles long. The first 42 miles have gradients not exceeding 1 in 40, and this portion is worked as an ordinary adhesion-line ; the remaining 12 miles are built on the Abt rack system, and have a ruling gradient of 1 in 12$, rising to a height of 5,613 feet abovemean sea-level. The gauge is 1 metre (3 feet 38 inches), and the minimum radius of the curves is 100 metres (328 feet). Of the whole line, 9 miles consists of curves, 53 miles being of the maximum curvature. There are four intermediate stations- Kullar, Adderley, Hillgrove,and Runnymede-which serve the adjoining coffee- and tea-estates, andare used as crossing- and watering-stations. The survey for the line wasa very arduous undertaking, owing to the dense jungle and steep hillsides which had to be traversed. Thevalley giving access tothe plateau is merely a V-shaped mountain-gorge with very precipitous sides, the lower slopes con-

Downloaded by [ UNIVERSITY OF IOWA LIBRARIES] on [11/09/16]. Copyright © ICE Publishing, all rights reserved. Proceedings.) WEIQHTMAN ON TEE NILGIRI MOUNTAIN RAILWAY. 3 sisting of a talus of slips, centuries old, plentifully strewn with boulders lying in positions of varying degrees of stability. Such features did not afford much scope for choice in the location of the line; and the ruling gradient having been decided on, the general route of the line was not difficult to determine ; all that was necessary was to start from the top of the valley and run a falling grade-trace down at the ruling gradient untilit reached the bottom, utilizingany side valleys passed en route to gain distance in places wherethe slope of thevalley exceeded the gradient of the line. TheGovernment decided that,with a view to possible con- nections with existing lines, the railway must be of the metre- gauge, and that the maximum gradient admissible was 1 in 123. AS it is desirable with the Abtsystem that the radiusof ourvature should not be less than one hundred times the gauge, this fixed the minimum radius of curves as 100 metres (328 feet). With these data, it was possible to lay out roughly the general course of the railway. The sides of the valleyshowed a succession of alternate ridges and ravines, so that it was obvious that the most economical line would beobtained byusing the sharpest mrve freely, keeping the line as far out aspossible when rounding ridges and as far in as possible whencrossing the intervening valleys. The line thus consisted of a series of reverse curves with the minimumadmissible length of straight (50 feet) between them. The general route havingbeen thus determined, the final location was a much more troublesome matter. A series of cross sections 25 feet apart or in some places 10 feet and even 5 feet apart, were taken, which enabled the position of the line to be altered and improved, so as to involve the minimum amount of work. It is obvious thatin a country where thecurvature of the ridges and valleys approximates somewhat to that admissible on the railway, it is possible to construct a very light line, benched in thehillside similar to a hill-road; but inthe case of the Nilgiri Railway the curvatureof the ridges and valleyswas much less than that of the railway, so that it was impossible to avoid deepcuttings through the ridges and high viaducts over the valleys. In most places bankswere quite out of the question, the hillsides being considerably steeper than the natural slope of the earth; so that it would have slipped away to the bottom of the valley unless supported by retaining-walls, whichwere avoided as much as possible. It then became a very nice point to decide, by help of the cross sections, to what extent it was desirable to vary the preliminary B2

Downloaded by [ UNIVERSITY OF IOWA LIBRARIES] on [11/09/16]. Copyright © ICE Publishing, all rights reserved. 4 WEIGHTMAN ON TEE NILGIRI MOUNTAIN RAILWAY. [Minutoa of location of the line by shifting it parallel to itself, in order to increase or decrease the cuttings or tunnels at theexpense of the adjoining viaducts or retaining-walls. Broadly speaking, there were three lines to choose from: first, the line in which the cuttings and viaducts were approximately equalin depth and height, averaging 60 feet; secondly, a line parallel to this but farther out, in which the cuttings had been reduced to a depth not exceeding 20 feet, necessitating correspond- ing increase in the height and lengthof the viaducts; and thirdly, a lineparallel to the first butfarther in, where the cuttings exceeded 100 feetin depth, necessitating their conversion into tunnels, the viaducts being so decreased aa to become little more than culverts. The first of these was unquestionably the cheapest : whether it would also be the safest depended entirely on the nature of the ground through which the cuttings would run. A cutting 60 feet deep on the centre lineis, in steep sidelong ground, a much bigger thing than it looks on paper, especially if the ground turns out to be bad and requires flat slopes. The second line was by far the most expensive, and,although safe as faras the cuttings were concerned, required a largenumber of retaining-walls, which, in a country with a tropical rainfall, would constitute a source of danger not to be lightly courted. The third line, consisting of a series of short tunnels with small culverts between, would be a very expensive one to make but would be absolutely safe. The conclusion arrived at was that if economy was the main consideration, and if there was reason to believe that good sound ground, not liable to slip, would be met with, the first line should be adopted ; but, otherwise, the engineer should go in boldly for the third or tunnel line, as, in fact, had been done on the Usui Railway in Japan.’ The Nilgiri Bailway waslocated principally on amean line with the cuts somewhat, in excess of the fills, the objects aimed at being, in addition to economy, (i.) to keep theline as far as possible on the solid, (ii.) to avoid the too frequent use of retaining-walls, (iii.) to avoid increasing the already heavy bridging, and (iv.) to reduce the banks toa minimum ; for, with a rack line, it is important bo use every precautionto guardagainst any possibility of subsidence of the road-bed. But for the Government ruling, a very great saving could have been effected byusing a narrower gauge. Numerous rack-lines

Minutes of Proeeedings Inst. C.E., vol. cxx. p. 43.

have been built on theContinent with a gauge of 0-80 mctre (2 feet 73 inches) and curves having a radius of 60 metres (197 feet), and such a line would undoubtedly have ‘‘ fitted ” the country better and have greatlydecreased the work. The gradient is not compensated on the curves, the lengths of st,raight between curves being so short (frequently not more than 50 feet) that, allowing for the vertical curves at changes of gradient, it would have been almost impossible to do this. Seventy- five per cent. of the whole line consists of curves, and to have compensated would have added more than a mile to the length. Further, on a line with sucha heavy gradient, theresistance due to the curves is so small, as compared with the resistance due to gravity, that it is hardly worth considering. The line has there- fore an uncompensated gradient of 1 in 123, or, in effect, a compensated gradient of 1 in 114. In several places the ground was so difficult and inaccessible that a very careful and elaborate triangulation, plotted to a large scale, was necessary in orderto locate theline. The most troublesome places were the Benhope Cliffs, where the line passes for 1,000 feet along the face of an almost vertical cliff 2,000 feet high, and the Burliar valley, where it crosses a gorge by a bridge 150 feet long and 120 feet high, and then immediately enters B tunnel 275 feet long in the face of the cliff. In both places the survey was very difficult, and ropes secured to jumpers let into the rock had to be used to get anyfoothold at all. It was found to be of very great advantage to build masonry “balance-point ” pillars, before the earthwork was commenced, at all points where bank and cutting met. These were built to true formation-level, and correct centre line; theythus served as permanent benchmarks and t,heodolite-stations during construction,and are available for use still.The servicefootpath was made from balance-point to balance-point, contouring round the spurs and up theravines. The earthwork was veryheavy throughout and amounted to about 40 million cubic feet; it consisted chiefly of hard rock or of boulders embedded inearth and disintegrated gneiss. These boulderswere of granite,and weighed inmany cases several hundred tons. Dynamite was the explosive chiefly used, and the consumption amounted to about 180,000 lbs. The line passes for a considerable portion of its length above and parallel to the public road, and great care was needed in the blasting-operations to guard against accident to the public. Very stringent ruleswere framed, with the result that, notwithstanding

Downloaded by [ UNIVERSITY OF IOWA LIBRARIES] on [11/09/16]. Copyright © ICE Publishing, all rights reserved. 6 WEIUHTMAN ON THE NILUIRI MOUNTAINRAILWAY. [Minutes Of the fact that several hundred charges were fired every day, no accident occurred to the public, although, unfortunately, several happenedto workmen, owing to carelessness orto disregard of the rules. No hard-and-fast rule was made with regard to the slopes of cuttings, each being dealt with according to circumstances; but they were generally taken out with slopes as steep as possible, in order (i.) to minimise the disturbance of the hillside above, and (ii.) to expose as little new surface as possible to the action of the weather. In heavy sidelong ground, if much flattening is done, the uphill slope becomes a serious matter, and the denudation of vegetation tends rather to encourage slips than otherwise. This policy naturally resulted innumerous slipsin the first heavy rains, but it was thought better to let nature point out the places where additional sloping was needed, rather than to go in for excessive slopingthroughout the whole lineat the outset. Catch-drains above thecuttings were quiteout of the question, owingto boulders and rocks and general roughness of the ground. Thegrowth of vegetation on the slopes of bothbanks and cuttingswas encouragedeverywhere. Experiments were made with different kinds of grass for turfing, of whichGuinea grasswas found to be the best, owingto the length and tenacity of its roots, which gave it great power of holding the soil together. The formation was everywhere 16 feet wide (Fig. 3, Plate l), and the greatest possible care was taken to see that it was effec- tually drained. In countrieswhere a rainfall of 6 inches in as many hours is of frequent occurrence this is a most important consideration. Ballast-walls of dry stone, 18 inches high, were built throughout the mountain section. The side drains were of the minimum dimension of 18 inches by 18 inches, and were pitched with dry stone. On thetop of formation G inches of large stone soling was laid; then G inches of small 2-inchballast, and afterwards 6 inches of boxing in ballast, put in after the platelaying was done. Allballast used was good sound brokengranite. The outer side-drains were turned off every 100 feet, except in a few long cuttings; the inner side-drains were led into culverts or to earthenware pipes under the line. Many of the smaller culverts were built in the manner recommended by Sir Guilford Moles- worth l-thatis, a new channel for thestream was run on a

* Minutes of Proceedings Inst. C.E., vol. cxx. p. 55.

Downloaded by [ UNIVERSITY OF IOWA LIBRARIES] on [11/09/16]. Copyright © ICE Publishing, all rights reserved. Proceedings.] WEIGHTMAN ON THE NILGIRI BIOUNTAINRAILWAY. 7 contour (with a slight fall) through the point where bank and cutting meet, and a short culvert was built there, instead of in the bottom of the ravine, where a very long one would have been necessary. The cost of the earthwork varied between la. 11 -3p. per cubic yardfor soft earth, and R.l 3a. 5p. per cubic yard for hard rock, including cost of explosives. The work was done by petty contract, chiefly by Moplahs from the west coast. There are nine tunnels on the line-all short ones-the longest being 325 feet. They were all driven by hand-labour, and onlyone gave any trouble and required skilled labour for the timbering ; seven of the nine were on curves of 328 feet radius and one was driven from two side adits in theface of the cliff as the tunnel-face was inaccessible. In tunnels through hard rock a top heading was run, and in soft ground where timbering was needed abottom heading. The lining, where required, was of stone with lime or Portland-cementmortar. The cost of theunlined tunnels was Rs.lOO ($7) per lineal foot, and of the lined tunnels Rs.180 ($12) per lineal foot. The air in the tunnels gets verybad when the engine hasa full load, especially if fuel has just been added ; this is due to the continuous up-draught caused bythe incline which makes the smoke, &C., travel at the same pace as the train; the tunnels are so short, however, that this hascaused but littleinconvenience. A section of halftunnel (Fig. 4) was used in two or three places where the line passes along the face of a cliff. The retaining-walls were numerous-about 120 in all-and of various degrees of importance, the biggest wall being 63 feet high and 200 feet long. At first they were all built of dry stone with a batter of l in 4 on the face, but afterwards all important walls were built in limemortar, and the batter was increased to 1 in 3, thehigh ones beingbuttressed also. Dry stone walls, however carefully built, are undoubtedly a source of weakness on a line subjected to excessive rainfall,and, in the Author's opinion, should not be used for heights over 10 feet : in the case of revet- ments pure and simple thesame objection does not hold. The bridgework was heavy for the length of line, comprising twenty-three large bridges and one hundred and thirteen small ones. The longest bridge,over the KullarRiver, was 450 feet long ; the highest, at Burliar, was 120 feet high. Of the large bridges, onlyeight wereover rivers properly so called, theremainder being over deep gorges, dry except after rain. The design of the large bridges was uniform, though slightly

modified to suit local circumstances ; several alternative designs were prepared, and it was found that the cheapest type to adopt was plate-girders on masonry piers, the fall in the exchange value of therupee precluding the use of thesteel piers originally intended. Excellent stone was obtainable along the whole route, but lime was not procurable and had to be brought up from the plains by road from Karamadi. Scarcity of sand also was a difficulty,for mountain gorges are not favourable to its deposit. Such sand as could be had was brought up from the plains, and most of it was of inferior quality, although the resultof a series of briquette tests showed that inferior sand, if the lime is good, does not affect the quality of themortar as much as isgenerally supposed. The masonry consisted of coursed rubbleset in lime mortar. The abutments were quite plain, with square return walls ; the piers, instead of being battered, had insets every 4 feet, as being neater and easier to build. The rate paid formasonry varied between Rs.10 13a. and Bs.13 8a. per cubic yard, accordingto the proximity of water and thedifficulty of access. The use of plate girders was decided .on, because most of the girders had to be laid on a gradient of 1in 124, and it was thought that, with any form of lattice girder, the rigid butting necessary at the lower end to prevent creep might possibly cause buckling; the girders areof steel and were designed according tothe Govern- ment-of-India rules, namely, double the moving load added to the fixed load, and a stress of 9 tons per square inch. Sixty feet was fixed as the maximumspan, because, a.s most of these bridges were on a 328-foot curve, anylonger span would have necessitated long cross girdersto provide for the curvature of the line on the bridge. For the same reason in all cases the road wascarried on thetop flanges, on transverse sleepers, thusrendering cross girders unnecessary. The versed sine with a 60-foot girder on a 328-foot curve is 1 foot 10%inches, so that by placing the girders andbed-stones 1 foot up stream out of the centre, and thus dividing the versed sine, it was possible to reduce the distance between centres of girders to 5 feet 6 inches, which was not too great for hardwood bridge-sleepers. All the pier-foundations were on bed rock, which was carefully benched, and in some cases steel jumpers also were let in. The only one tha,t gave any trouble was the centre pier of the Bawani Bridge, which was on two 10-foot masonry wells sunk by divers through the boulders in the bed of the river. Besides forty-five smaller spans, there are thirty-two spans of 60-foot girders, and

Downloaded by [ UNIVERSITY OF IOWA LIBRARIES] on [11/09/16]. Copyright © ICE Publishing, all rights reserved. Proceeding8.1 WEIQHTXAN ON THENILGIRI MOUNTAINRAILWAY. 9 thesewere put together and riveted complete withall cross bracing, bridge-sleepers, etc., at the base, run up on two bogie trucks,and pushed across into place by an engine overa tem- porarybridge formed of sleeper-stacks and rolled beams. This effected a very great saving of time as compared with the usual practice of putting together and riveting in. situ. The 100-foot spans over theBawani required different treat- ment. As thisriver is subject to floods atall ~easons of the year, falsework was inadmissible. The spans were riveted up on the bank complete, with all cross girders and bracing,etc. ; a low- level surface-line with four lines of rails was laid between piers on cribs across the river, and on this ran a timber gantry carried on four bogies, and of the full height of the piers. The ends of a pair of 100-foot girders were placed on this gantry, which was then traversed across, carrying the girders withit ; in this waya complete span weighingbetween 50 tons and 60 tons was launched in half-an-hour. In one case only is the span of 60 feet exceeded on the ghat section, and that is at Burliar, where an SO-foot span with buckle- plate flooring was used. This gave some little trouble in erection, as it spanned a rocky gorge 130 feet deep on a 328-foot curve, and with a curved tunnel at one end, through which the launching had tobe done, thus precluding theuse of derricks or other similar appliances. A low-level girder bridge, with a span of35 feet, was constructed across the bottom of the gorge, and on this was built a timbertrestle nearly 60 feethigh. This formed the basis of a temporary bridge, over which rails were laid and the girders were run across on bogies, having first been riveted up in the tunnel. On themountain section most of thegirders were laid on a gradient of 1 in 123, and it became necessary to devise some means of preventingthem from moving downhill. On single- span bridges a heavy angle-bar, 6 inches by ti inches, was riveted to the bottom booms of the girders at the lower end, and this angle-bar, as well as the ends of the girders thomselves, butted against the masonry of the lower abutment, the upper ends of the girders being left free for expansion. On bridges of more than onespan, a pair of heavy cast-iron bed-plates (Fig. 5, Plate 1) was securely bolted to the top of each pier. The top surface of this bed-plate wak parallel to the incline, and to it were bolted the girders, the upper end of the lower span having provision for expansion, and the lower end of the upper span beingfixed to the bed-plate and provided with an angle-bar, to butt against it as for

Downloaded by [ UNIVERSITY OF IOWA LIBRARIES] on [11/09/16]. Copyright © ICE Publishing, all rights reserved. 10 WEIUHTMAN ON THE NILOIRI MOUNTAINRAILWAY. [Minutes of single spans. These precautions have been successful, and so far no movement of the girders has takenplace. Thepermanent way consists of 50-lb. steel flat-footedrails, 28.14 feet long, laid on wooden sleepers, eleven to the rail, with deep six-holedfish-plates, weighing 40 lbs. perpair, fitting in between the sleepers (Figs. 6 and 7).

The sleepers are of Burmese " Pyngadu," a veryhard, dark compact wood, which when well seasoned resists the attacks of white ants. They are spaced 2 feet 62 inches (780 mm.) apart, the ordinary size being 6 feet by 8 inches by 4fi inches ; but on the ghat section, where they have to carry the rackalso, the thickness has been increasedto 6 inches,to guard against anything like warping, which, however slight, would alter the relative height of rack and rail. On allgradients steeper than 1 in 40 a double Abt rack is used (Fig. 8). FromKullar to Coonoor (12 miles) therack is continuous, except for three short breaks where the stationsoccur. The rack-bars are 3.116 metreslong (covering fourbays of sleepers) and 22 millimetresthick (Fig. 9). Thetwo bars are laid so that they not only break pitch but also joint. They are made of flat bars of steel, with a tensile strength of 30 tons per square inch, and the teeth are formed by machine-slotting from the solid. Thegreatest care was exercised inmaking them, as regards pitch, shape of teeth, length of bar and position of bolt- holes. Everybar was applied in the works to a metalstud tsmplateto test its accuracy before it was accepted. The rack is carried by cast-iron chairs which are fixed to the sleepers by two %-inch fang-bolts; the spring entering-tongues are on steel sleepers and are of the ordinary Abt pattern (Fig. 10). The whole of thismaterial was manufacturedby Messrs. Cammell & Co. of Sheffield, whodevised aspecial machine for slotting the teeth. This was the first instance of any rack- railway material being made in England. The price paid for the steel rack was S14 10s. 9d. per ton f.o.b., plus a patent royalty of S5 29. 9d. per ton. This rate was considerably lower than those quoted by the German firms who had hitherto had the monopoly. Therate per milefor the double rackwith chairs and all fastenings, but excluding rails, sleepers and laying, was 52,408, equivalent to 16s. per yard. The weight per yard was 90 lbs. for all bars,chairs, and fastenings. Thespring entering-tongues cost 532 15s. 2d. each, f.o.b. complete. The whole of thepermanent way had to belaid with the greatest exactitude; all the rails were bent truly to the curves

Downloaded by [ UNIVERSITY OF IOWA LIBRARIES] on [11/09/16]. Copyright © ICE Publishing, all rights reserved. Prooeedings.] WEIUHTYAN ON THE NILGIRI MOUNTAIN RAILWAY. 11 by machine, and the laying of the rack itself was a somewhat troublesome process. Thespacing of the sleepers is fixed absolutely by the rack, and owing to theuse of deep fish-plates (Fig. 7) it became necessary to have therail-joints not only square witheach other but also exactly midway between the two adjacent sleepers. There was no difficulty in doingthis on thestraight, but on curves it was necessary to use rails of different lengths for the outsideand inside. Ifthe joint did not come exactly inthe centre, it was possible tonotch either the upper or the lower sleeper to receive the fish-plate, but no deviation of more than l inchwas allowed. Rails of therequired lengths for allthe different curveswere cut, drilled, and bent by machine in the depot, and were painted different colours and stacked separately; a table being given to the man in. charge of the rail-bending machine, showing the versed sine required for different curves. The sleepers also were notched for the rail-cant, and the rack- chairs were fixed on them in the depot before they were taken out ; the rack-bars required for curves were also bent and stacked separately. Theplatelaying procedure was as folIows :-Sleepers with rack-chairsattached were spread ahead correctly spaced; a second gang followed, fixing the rack loosely; and the straight- ening, adjusting, and tightening of it were done by a third set of men following. Special care was given to the joints; a steel stepping-gauge, embracing three teeth of each rack, was left in the rack at the joints, while the fish-bolts were being tightened up. Twogangs followed, layingthe adhesion-rails, the special points in which care was needed being to keep the rack truly in the centre of the gauge (on the straight) and to keep the top of the rack exactly the correct height above the tops of the rails. This latter is an important point, for if the rack is too low the pinion cannot engage properly, andit if is too high there is danger of it jamming. The layingof the rack was kept100 feet or 200 feet ahead of the rails, an attempt to lay the adhesion-rails first and therack afterwards proving unsuccessful. Theplatelaying was done telescopically, as it could only be commenced where there was a break of rack, and could not proceed in both directions on account of the difficulty of correctly junctioning the pitching and stepping of the rack-bars. The use of wooden sleepers was somewhat of a novelty ; on all the continental Abt lines steel sleepers are used, the only other lineusing wooden sleepers beingthe Pike’s PeakRailway in America. Wooden sleepers are cheaper, more easily renewed, less

Downloaded by [ UNIVERSITY OF IOWA LIBRARIES] on [11/09/16]. Copyright © ICE Publishing, all rights reserved. 12 WEIGHTNAN ON THE NILCtIRI MOUNTAIN RAILVAY. [M*uteS of damaged by slips or derailments, give a more flexible road and offer more latitude in the spacing, as the chairs need not be fixed exactly in the centre of the sleeper, but can be moved slightly uphill or downhillas best suits the rail-joints. The cost of platelaying, including rough packing, was 2s. per yard, and the progress rarely exceeded 500 feet perday; any attempt to increase this resulted inbad joints and careless laying. The rack-barswere made 2 millimetres short at each end to allow for expansion and contraction, so that at each joint-chair there was a gap of 4 millimetres. On the straight this gave no trouble, as the space was the same throughout, and the joint-pitch was always correct ; but it is obvious that on curves the inner rack must be slightly shorter than the outer, and that, the rack- bars being all of the same length, this difference must be allowed for at the joints. Hence, on curves, all inner joint-pitches had to be made slightly tight, and all outer joint-pitches slightly slack. It wasessential to divide the error, because if the inner joint- pitch were made correct the outer one would be so wide as to be dangerous, and vice versa. The difference in length on a 328-foot curve was 2 millimetres, so that it was necessary to make the joint-gaps of the inner rack 3 millimetres wide and those of the outerrack 5 millimetres. This difference wouldbe reduced by using shorter bars of two- instead of four-sleeper bays. 1 For the adhesion-rails & inch was allowed for expansion at the joints.The observations of theAuthor, however, tend to show that, on a line consisting principallyof curves, expansion and contraction does not take place parallel to the line, but that theforce is expended in slightly bulging or flattening thecurves, owing to the resistance of the ballast at the sleeper-ends being less than that of the fished joints.Inspection of theballast on curves distinctly showed that there had been lateral movement of the sleepers. Ifthis theory is correct, it wouldbe possible, on a mountain railway where curves largely preponderate, to lay the railswith ends butting,thus giving increased smoothness of running and less wear and tear to rollingstock. No precautions have been takento prevent creep, 3s with the form of permanent way and rack used it is believed that its occurrence is impossible. The deep form of fish-plate (Fig. 7) prevents a rail from moving downwards without pushing before it the sleeper supporting its lower end; but this sleeper, being chained to all the other sleepers by the rack, cannot move unless it drags them all with it, and the total resistance of the ballast is sufficient to prevent this. In fact, the rack-bars and rails combined

Downloaded by [ UNIVERSITY OF IOWA LIBRARIES] on [11/09/16]. Copyright © ICE Publishing, all rights reserved. Proceedingn.1 WEIGETMAR QN THE NILGIRI MOUNTAIN RAILWAY. 13 form a sort of rigid frame, the rails acting as struts and the racks as ties. All changes of gradient are rounded off by vertical curves of large radius (usually 3,759.4 feet), which prevents anything of the nature of a jerk to the train as it passes from one gradient to another. AS the enginepushes the train it is always at thedownhill end ; consequently, when approaching a rising gradient, the train will be on the incline before the engine, and it is thus necessary at each station or break of rack to commence the rack a train-length (150 feet)in advance of the commencement of the incline. On a falling gradient, that is, at the downhill ends of stations, this is not necessary, and the rack begins slightly below where the incline commences. The superelevation on curves is greater than would be given by using the ordinary speed-formulas : it ranges between 15 inch on the curve of minimum radius (328 feet) and 2 inch on that of 716 feet radius. On girder bridges this superelevation was given by raising the outside girder, thus avoiding excessive notching of the bridge-sleepers. On all curves the line was laid slack to gauge, the amount of slackness varying between inch on 328-foot curves and t inch on those of 716 feet radius. It was foundpreferable to give thewhole of this slackness to the inside half of the gauge instead of half on each side. Whenpassing round curvesthe tendency is for the leading wheels of the engine to hug the outer rail, so that if the rack is placed the correct half-gauge from theouter rail the gearing of the pinion is better than if the rack were placed truly in the centreof the widened gauge. The Authorconducted a series of experiments to determine the exact position which the pinions take when passing round curves. The teeth of the two pairs of pinions were dabbed with red and black paint respectively, and as they passed over and depressed springboards fixed to the sleepers, a record was left by the paint of the positions taken by the two pinions with respect tothe rack. Theresults showed thatthe leading pinionwas well overtowards the outside of the curve and the trailing one towards the inside; which gives a slightly crab-like motion to the engine, and means some loss of power in friction till the teeth become worn to this condition of things. The experiments also showed that if any widening of gauge was givento the outer half, theleading inner pinion approached perilouslynear to the outer rack, andas the rack-teeth break pitch this was a thing to be guarded against.

Downloaded by [ UNIVERSITY OF IOWA LIBRARIES] on [11/09/16]. Copyright © ICE Publishing, all rights reserved. 14 WETUHTMAN ON THE NILGIRIMOUNTAIN RAILWAY. [Minutes of The rolling stock consists at present of four rack-locomotives sixteen goods wagons, four first-class coaches, four composite coaches, and four brake-vans. The leading dimensions of the engines are shown in Fig. 11, Plate 1. They are what are known as " combined " Abt engines, that is, they can run on either a rack- or an ordinary line. There are four cylinders, the outside pair, 114 inches by 18 inches, for the adhesion-wheels, and the inside pair, 10 inches by 14 inches, for the rack-pinions. Each engine has six wheels, 2 feet 6 inches in diameter, the trailing pairs being coupled ; the wheel-base is 10 feet, and the total weight in working order is 33 tons. This wheel-base was somewhat long for the sharp curves, but the wear of the tires has been very much decreased by the use of a jet of hot water. Theengines carry 625 gallons of waterin side tanks and 1 ton of fuel in a rear bunker. They were built by Messrs. Beyer, Peacock & Co., of Manchester, who have introduced in them some novel features. In the ordinary Abt engine the frame carrying therack-pinions and gear is slung from two of the main axles by means of two additional bearings on each axle between the main frame-plates. The object of this is to prevent the motion of the springs from influencing the height of the pinions above rail-level, as it would if they were carried by the main frame. In the Peacock engine the rack-frame is attacheddirect to the main axle-boxes, thus avoiding the use of the intermediate bearings. Another improve- ment is that the rack-pinion is not driven direct, as is usual, but by spur-gearing, and that both the leading and trailing pinions aredriven by the samespur-wheel, thusincreasing the safety and making the pressure on the rack-teeth half what it is with the ordinary Abt engine, in which all thepower is transmitted by one pair of pinions only, the second pair being merely used to give additional brake-power. The load taken by these engines up inclines of 1 in 124, at 44 miles per hour, is nominally 60 tons, excluding the weight of the engine ; but although in certain specific trials this load has been taken, for ordinaryrunning it hasnot been so far possible to ensure generallya greater load than 45 tons to50 tons. As the same trouble occurred with the UsuiToge engines,l and also with those of the Transandine and Snowdon lines, there must be some reason for this divergence in the case of rack-engines between the theo- retical load and the actualload taken.

* Hinutes of Proceedings Inst. C.E., vol. OM. p. 47.

Downloaded by [ UNIVERSITY OF IOWA LIBRARIES] on [11/09/16]. Copyright © ICE Publishing, all rights reserved. Proceedings.] WEIGETMAN ON TEE NILGIRI MOUNTAIN RAILWAY. 15 In mountainous countries it is nearly certain that damp, moist weather will be the rule rather than the exception, and that the normalcondition of therails will be greasy; so thatwhile a coefficient of adhesion of one-fifth, or even higher,might be possible on an ordinary railway, when designing an engine for use on a mountain line such as this, the coefficient adopted in the calculations should, in the opinion of the Author, not be greater than one-seventh. In the case under consideration the makers' calculation showed that a coefficient of would be necessary in order to obtain the full power of the adhesion-cylinders, and the opinion was expressed that with thesteam-sanding apparatus such a coefficient should be obtainable. TheAuthor differs on this point, and does not think it would be possible to rely on such B high coefficient, even ifsteam-sanding were practicableduring the whole ascent, which it is not. Further, when determining the load which a rack-engine should take, an unknown factor has to be dealt with, namely, the friction of the rack-gearing. For an ordinary engine, an allowance of between 10 lbs. and 12 lbs. per ton would be ample at low speeds to cover the rolling-resistance of the engine, and the friction of the motion and gear; but in a rack-engine there must be added to this not only the friction of the rack-engineitself but the frictionbetween the pinions and the rack. It would not be correct to assume that the power is transmitted b$ the rack-gearing without loss, for, as has already been explained, on curves the rack is not perfectly accurate. To provide for slightinequalities in the rack, theengine- pinions are in two parts, and are provided with six spring keys (Fig. 13), which have the effect of giving a certain amount of elasticity to the teeth and ensure each pinion taking up its fair share of the work. The engines work very smoothly on the rack, and the gearing afterthe teeth have become slightlyworn is perfect. On the whole, they are doing their work well, the difficulty of keeping steam which oecurred at the outset having been entirely ovor- come by using better fuel and by altering the spacingof the fire- bars and the form of the blast-nozzles. The cost of each engine was S2,600, or at the rateof about 275 per ton, as against S45 to S50 per ton for ordinary enginesof similar weight and gauge. The trains are very powerfully braked. The engine is provided with the Chatelier airbrake, on both rack- and adhesion-cylinders, and,in addition to an ordinary hand-brake, hasthe vacuum automatic brake acting on all six wheels. Each rack-pinion also is provided with a powerful hand-brake actuated by another hand-

Downloaded by [ UNIVERSITY OF IOWA LIBRARIES] on [11/09/16]. Copyright © ICE Publishing, all rights reserved. P6 WEIGl3TXAX ON !!?HE BILUlRI MOUNTAIN RAILWAY, [Minute8 df lever from the cab. This brake consists of a steel band withbrass linings, the brasses being serrated to fit the drums against which they press, and the drums being keyed'onto the pinion-shaft. Before the line was opened for traffic a series of brake-experiments was made with a fully-loaded train of 100 tons gross weight, and the results were most satisfactory. With an ascending train at speeds of 6 miles, 8 miles, and 10 miles per hour, stops were made in 24 feet, 36 feet, and 60 feet respectively; while with a descending train on a 1 in 12& gradientat speeds of 4 miles, 5 miles, 6 miles, 7 miles, 8 miles, 10 miles, and 12 miles per hour, stops were made in distances of 54 feet, 70 feet, 92 feet, 112 feet, 133 feet, 243 feet, and 425 feet respectively. The descent is usually made on the Chatelier brake only, this ordinarilybeing found sufficient to control thetrain. The vacuum- and hand-brakes are availablefor emergency stops. No Paper on rack-railways would be complete without some remarks on the vexed question of thedanger of the pinion mountingthe rack. TheAuthor has had exceptional oppor- tunities for studying this matter, and has caused wilful derailments in order to investigate it more thoroughly. The conclusion arrived at is that inalmost every case the mounting of the rack is the result and not the cause of the derailment. If the road is not in good order the engine will become derailed just as an ordinary engine would; the result is that the pinion mounts and damages the rack, and this is erroneously assumed to be the cause of the accident. If everything is in good order there is no more reason why a rack-engine should leave the road than an ordinary engine; on the contrary, there is less reason, for the rack-bars, breaking pitch as they do, act in some slight degree as check-rails; but if a rack-engine does get off the road the consequences are naturally more serious, for bythe disengagement of the pinion the engine's most effective brake is rendered useless. Toguard against dangers of this sort it is essential thata rack-line be laid with the greatest care and accuracy and be kept in perfect order, special attention being given to packing with good sound ballast. Packing should always be done from the lower side of sleepers, and more than usual careshould be taken that no packing is done in the centre of the sleepers, and that there is no subsidence of the road-bed. It is most important also to lay the line on the curvesmathematically correct. One apparently inexplicable derailment was found to have been due to careless bending of a rail, by which all the curvature had been given at one place instead of being evenly distributedover the whole length.

Downloaded by [ UNIVERSITY OF IOWA LIBRARIES] on [11/09/16]. Copyright © ICE Publishing, all rights reserved. prowm~ings.l WEIGHTHAN ON rn~NILGIRX MOUNTAIN RAILWAY. l? It is impossible for a pinion to mount the rack unless there bean error of not less than fr inchin the rack-pitch. From thenature of thebars this could only happen at a joint, andthere only ifthe line were actuallybroken or seriously damaged. The bars are not strong enough to bear the weight of an engine-they bend before lifting it; even a stone on the rack is not sufficient to cause mounting ; it is eitherforced between the barsor crushedbetween theteeth. The only way in which mounting is conceivable is by the pinions becoming locked, and this could only occur with a very powerfulbrake. In no case should a brake of such power be used as to render locking of the pinions possible. On theNilgiri Railway the rack-brakes,both of the engine and of the vehicles, are worked by hand only, and it was found byexperiment that it wasimpossible toexert sufficient force on the lever to prevent the pinion from rotating. All the derailments occurred during construction, before the line was properly packed; since then there has not been the slightest trouble except in the matter of slips in the cuttings. The gearing improved after the teeth had become slightly worn, and is now perfect; the “staggering ” of the rack-teeth prevents the jerky motion felt on some of the older rack lines, and the transitionfrom the adhesion- to the rack-sections is hardlynoticeable either in the carriages or on the footplate. The working of the Abt system on this line may be pronounced a distinct success. Allthe rolling stock is carried on bogies. The coaches and brake-vans are 36 feet long, and each weighs between 11 tons and 12 tons tare. They cost $920, 5800, and S570 each for first-class and composite coaches, and brake-vans respectively, including all woodwork, fittings, and trimmings. The goods wagons, of pressed steel, are open, low-sided, and 30 feet long; they tare 6 tons, and carry 22 tons of goods-an unusually high ratio(Fig. 14, Plate 1). All rolling stock is fitted with the vacuum automatic brake, as well asa rack-brake worked by brakesmen, one of whom travels on every vehicle. The Jones central-buffer coupling is used, and the Winter electric communication is about to be added. At each of the crossing-stations there is a short length of level road, laid without therack. This enables points and crossings (1 in 6) of ordinary pattern tobe used instead of the rather complicated rack ones. The accommodation consists only of a crossing siding, a lay-by siding, water-tank and ashpit. At the terminal stations ample sidings, engine-sheds, ashpits, goods-sheds, platforms, etc., are provided. As theengine-tank only holds 635 gallons, it is necessary for all asceuding trains to water ateach station. [THE INST. C.E. VOL. CXLV.] C

Downloaded by [ UNIVERSITY OF IOWA LIBRARIES] on [11/09/16]. Copyright © ICE Publishing, all rights reserved. 18 WBIUBTIXAN ON THE NILCXRIMOUNTAIN RAILWAY. [Minutes of The speed is limited to 8 miles per hour on the ghat section, and 20 miles per hour on the adhesion portion, and for safety the engine is always at the downhill end of the train, and pushes instead of pulls. The use of turn-tables at the termini is thus unnecessary. Thereare three crossings of the main road, the first by an underbridge,the second by an overbridge, andthe third by a level crossing. All the secondary roads are taken over by level crossings (Fig. 12), while numerous bridle-paths connecting the coffee-estates cross by light overbridges formed of old rails. The line is now being worked by the Madras Railway Company, who have prepared a very completev code of rules for working, embodying every possible precaution to ensure safety, and with special rules to guard against the breaking away of a wagon at any of theintermediate stations on theghat. An excellent system of patrolling the line isalso in force, and every portion is traversedby the watchmen at leastthree times aday, night running not being allowed for the present. The grease used for lubricating the rack is a mixture of tallow, soft soap, castor-oil, andblack-led, boiled together, it being necessary to use a lubricant whichdoes not harden,does not readily melt in a hot sun, and is not palatable to ants or other insects. Therack is greased once aweek by agreaser, butgreasing automatically, as theengine-pinions travel over the rack, is contemplated. At present four trains each way are run daily, two passenger and two goods. The passenger fares charged are Rs.10, Rs.5, and R.l, for first, second, and third class respectively, for the ascending journey,and half these rates for the descending journey.The maximum goods rate allowed by Government is Rs.10 per ton. The line is worked on theabsolute block systemwith Winter instruments and the manuscriptline-clear ticket. In conclusion, a few remarks may be offered on the important question whenand under what circumstances a rack-line is to bepreferred toan adhesion-line. In the case of therailway here described, the circumstanceswere peculiarlyadapted for making a steeprailway, and anordinary adhesion-line was almost out of the question. If the same curvesand gauge had been adopted, an adhesion-line would have cost as much per mile (less a small amount for the cost of the rack itself), and even with a gradient as steep as l in 25 the length would have been doubled andthe cost nearly so, andthe scheme would have become financially impossible. At the same time, while allowing

Downloaded by [ UNIVERSITY OF IOWA LIBRARIES] on [11/09/16]. Copyright © ICE Publishing, all rights reserved. Proceedings.] WEIUHTMAN ON THENILGIRI MOUNTAINRAILWAY. 19 that' a rack-line was the most suitable in this case, the, disad- vantages of the system mustnot be lostsight of. As longas everything is in good order a rack-railway works perfectly; but the whole thing is in reality a machine, and, like a machine, is easily put out of order. A small boulder falling on a rack-bar is sufficient to bend it and to stoptraffic until it has been replaced. If a rack-railway is to be a success it must be verycarefully and substantially built and mustbe maintained in perfect order. Every mountain railway is a problem in itself, which must be solved independently. It is a mistake to suppose that, because a special system has proved a success in one place, it will necessarily be so in another where the circumstances may be quite dissimilar. Rack-railways have proved themselves to be most ingenious and efficient means of negotiating steep gradients, and to be satisfactory in every way when used in the right place. It is impossible to formulate any rules as towhen to use them, but, unless the circumstances arevery exceptional, they shouldbe avoided on important or trunk lines. The interpolation of a length of rack on a main line wouldbe almost as objectionable as a break of gauge, and in most cases the alternative adhesion-line would be decidedly preferable. Generally speaking, the most suitable place for a rack-railway is for a short branch line to reach a hill-station or other elevated spot, provided (cc) that the traffic will not be very heavy; (b) that thereis no probability of thisbranch being extended at some future time and becoming a portion of an important trunk line; (c) that the averageslope of the valley or country to be traversed lies between 1 in 5 and 1 in 15, enabling a fairly direct line of, say, 1 in 10 to 1 in 12 to be made at a moderate cost; if the slope of the ground is flatter than this an adhesion-line will probably better aerve the purpose. The cost of the line was approximately S15,OOO per mile, which compares very favourably with others of a similar character. An extension of 11+ miles is contemplated,consisting of 33 miles of rack and 72 miles of adhesion-railway ; the esti.mated cost of this is S11,OOO per mile. Theline was constructed by the Author, with Mr. E. S. Alexander, Assoc. M. Inst. C.E., and Mr. A. H. Butcher, Assoc. M. Inst. C.E., as District Engineers, the Consulting Engineer being Mr. Horace Bell, M. Inst. C.E.

The Paper is accompanied by ten tracings, from which Plate 1 has been prepared. c2

...... ~ ...... l 7 SECTION 4T LEVELCROSSING.

p.. SECTION OF HALF TUNNEL.

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