The Cape Government Railways
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252 BROUSGER NO CAPE GOVERNMENT RAILWAYS. CS'31ected (Paper No. 2049.) " The CapeGovernment Railways." By WILLIAMGEORGE BROUNGER, M. Inst. C.E. THEpast few years have witnessed the construction of a somewhat extensive system of railways in the Colony of the Cape of Good Hope. These lines of railway have been carried out on the 3 feet 6 inches gauge, and include three principal divisions converging towardsthe Diamond Fields; namely, theWestern system, the Midlandsystem, and theEastern system, The generaldirection of the Western system is north-east, crossing the rivers forming themain drainage of thecountry, and intervening ridges, and the bridges are consequently both numerous and important. The illidland system runs north, following chiefly the main drainage of the country; while the Eastern system is characterized by its severe gradients and curves. Thecountry occupied bythese systems of railway, and the course pursued by the lines, is shown in the accompanying map of the Cape Colony, Plate 11. The maximumelevation above sea-level attained on the Western system is 4,572 feet, and on the Eastern system 5,446 feet. Gradients and Curves.-The percentages of different gradients and level on the several systems are as follows, the .percentage being in each case that of the mileage of the whole system :- I j Per cent./ Per cent. ['er cent. I Per cent. lPcr cent. Per cmt. Per cent. Western system . I 4.06 1.84 3.00 11.67 12.45 54.64 12,32 Midland ,, ~ 9.30 4.50 13.96 17.00 -1 4.50 10.07 40.4G Eastern ,, . 17'11 20.77 7.87 11.64 7.54 18.37 16,Gi 1 l The aggregate lengthsof curves of different radii on the several Bystems are :- Downloaded by [ University of Liverpool] on [16/09/16]. Copyright © ICE Publishing, all rights reserved. Papers.] BROUNGERCAPEGOVERNMENTON RAILWAYS. 253 Total Radius in Chains. Length ~ __ __ T of Sptem. 5.: 5 to 6. 8 to 10. 10 to 15. 15 to 40. Over 40. Ms. Ch. Ms. Ch. Ms. Ch. Ms. Ch. Ms. Ch. Ms. Ch. Ms. Ch. Western,system . 642 60 0 75 1 75 1233 7 26 60 75 49 72 Midland ,, . 589 13 .. .I 26 51 28 26 78 68 16 31 Eastern ,, . 291 65 1 19 9 25 33 15 1562 -52 40 10 63 BRIDGESAND CULVERTS. Owing to the difficulty in procuring.goodbricks, the importance of time, and the scarcity of skilled labour, iron superstructures, even in the case of bridges of small span and open culverts, have been largely employed. Arches, however, have been resorted to more extensively on the Easternsystem. The character of masonry employed has varied between fitted and coursed rubble, and block- in-course, according to the nature of the stone available, ashlar having, asa rule, been avoided. Cement has been largely em- ployed instead of lime for mortar, owing, not only to the difficulty in obtaining the latter of good quality, but to the saving of cost of carriage consequent upon the much larger admixture of sand which the former will bear. In some cases of rivers which bring down trees and heavy drift during floods, a plate-diaphragm stiffened by T or L iron between the two cylinders forming each of the piers, has been adopted in lieu of open bracing ; this gives the effect of solid piers, and saves them from the strain which might result from large accumulations of heavy drift. The nature of the country traversed is shown by the following statistics of waterway on the respective lines and systems. Name of line or section. Waterway per mile. Feet. Worcester to Beaufort West ..........53.0 Western system .............38.0 Zvaartkops to Graaff-Reinet. .........17.0 Midland system, including bridges over tidal rivers ...24.0 9, ,, without ,, ,, 1, ...20.0 First 50 miles of theEastern line ........ 6 '6 Whole Eastern system ...........30'0 On theEastern system there are eleven bridges of 100-feet opening and upwards, with a total waterway of 1,798 feet. On the Downloaded by [ University of Liverpool] on [16/09/16]. Copyright © ICE Publishing, all rights reserved. 254 BROUNGERON CAPE GOVERNMENT RAILWAYS. [Selected Midland there are, including those across tidalrivers, fourteen bridgeswith a waterway of 4,229 feet;and on the Western, twenty-one such bridges with a waterway of 5,743 feet. All the bridgesare under bridges, as over bridgeshave only been em- ployed in exceptional cases, not exceeding half-a-dozen throughout the Colony. EARTHWORKS. The formation width varies on the different systems, and under varied circumstances from l5 to 18 feet, the smaller width having beenadopted inshort cuttings with but little drainage. The slopes employed have,except inthe caseof rock and shale, generally been 1 to 1 for cuttings, and 14 to l for embankments. FENCING. Fencing, as a general rule, has not been provided as a part of the railway, except in crossing cultivated ground, which forms a small percentage, or where the lines traverseland which was previously enclosed, which also forms a smallproportion of thc whole. Cattle are supposed to be prevented straying on the line by the herdsmen. In the case of freehold property, the amount of conlpensation paid for expropriation covers this risk of loss, and in the case of quit-rent, the Government is entitled to take land and materials without compensation. Nevertheless it has in some instances contributed a portion of the expense of proprietors who are prepared to bear the other part. PERMANENTWAY. Theweight of rails was fixed by the Governmentupon the recommendation of the Chief Inspector of Public Works, prior to the passing of the Acts of Parliament ; but Mr., now Sir, Charles Hutton Gregory, E.C.M.G., when appointed Consulting Engineer, strongly urged the use of a heavier section, and an increase in this direction to 45 lbs. was, after the supply of a small portion of theoriginal weight, accordinglyadopted. Steel of the same section is employed in the cases of gradients of l in 70 and steeper, also generally for the outer rail of curves of 10 chainsor less radius. This section was employed for thelines sanctioned by Parliament in the years 1873-4, including the few miles laid with Downloaded by [ University of Liverpool] on [16/09/16]. Copyright © ICE Publishing, all rights reserved. Papers.] BROUNGER ON CAPE GOVERNMENT RAILWAYS. 255 40-lb. rails. Therails are spiked or bolted to creosoted Baltic sleepers, 7 feet by 9 inches by 44 inches, and fished between the sleepers. With a view to check the tendency to spread of gauge round thesharp curves of theHex RiverMountain on theWestern system, bowl sleepers of Livesey’s pattern for a few miles of road were ordered for the sake of the wrought-iron tie; all the different kinds of fastenings employed being found to yield in the case of wooden sleepers, even where hard wood was employed, though the latter checks the tendency to some extent. This piece of road has answeredwell under a very trying traffic.Most of the sleepers are of cast iron, but a length of 1 mile is laid with wrought iron, and of the latter nota single sleeper has had to be replaced ; many of the former, however, are broken in the process of packing. The rails ordered for the last extensions, about 562 miles, arc 60 Ibs. in weight, all of steel, the fastenings being of the same character as for the lighter rails, while the wooden sleepers for the heavier rails are 7 feet by 10 inches by 5 inches. In consequence of the difficulty and uncertainty in obtaining wooden sleepers, the increase of their price, and delay in procuring them, it was decided to try iron sleepers on a more considerable scale, and wrought-iron troughsleepers for 364 miles, and wrought- iron bowl sleepers for 739 miles, both of Livesey’s patterns, have becn laid down. As these sleepers have only recently been brought into use, it would be premature to say much as to the result of experience ; there are, however, certain points which are palpably evident. First,both kinds require carefulpacking. In the case of the bowls, if this is not done, they are apt to get out of level transversely, and the result is a cant which throws the line out of gauge. In thesecond place, special care is essential in thc manufacture of both kinds, particularly in thefixing of the jaws, otherwise the gauge is affected ; and where irregularity occurs in the spacing of holes in the tie-bars, play is given on curves with bowls by placingthe cotter on the inside,instead of the outside of the bowl, and where much play is required, as on very sharp curves, this is done with both bowls. With the iron trough sleepers, it is desirable that special ones should be provided for sharp curves, with allowance for play, such sleepers having unmistakably dis- tinctive marks to prevent confusion, or otherwise some safe means of adjusting the jawsfor gauge. Thirdly, more care is requisite as regards ballast, and this has been a source of some trouble. It is undesirablc that ballast should Downloaded by [ University of Liverpool] on [16/09/16]. Copyright © ICE Publishing, all rights reserved. 256 BROUNGER ON CAPE GOVERNMENT RAILWAYS. [Selected be coarse for these sleepers ; but it is often difficult to obtain it fine, it being sometimes necessary to use broken stone for top as well as bottom ballast. In manyparts of thecountry disintegrated shale has been employed as top ballast, underwhich circumstance it has been found desirable to have a bottom layer of stone for the sake of drainage, and to give a substantial bed.