LIGHT RAILWAYS, MILITARY. These are 6ocm. gauge railways laid with steel rails, weighing 20 lb. to the linear yard of rail, on sleepers weighing from II to 221 lb. each, accord ing to the weight of the rolling-stock used, and laid 2ft. 6in. apart on a ballast track, the ballast consisting of sand, gravel, mine earth or burnt clay.
During the latter part of the World War, 1917-18, light rail ways were very extensively used on the Western front for trans porting supplies to the smaller supply depots away from the standard-gauge railways, and ammunition to the heavy gun and howitzer positions. During 1917-18, I,78om. of light railway were laid, but only about half of this was ever used. While the war was stationary light railways were of very great service to the armies, but as soon as a retreat or a continued advance took place they became out of action. They are not economical, the maintenance alone during 1917 being on an average 15 men per mile, which, as the lines became consolidated, was reduced to five men per mile. The average effective haul of a locomotive was 23 train miles per day, and that of a tractor was 20 train miles per day. The aver age coal consumption per locomotive was 62 lb. of coal per effec tive train mile and the average petrol consumption per tractor was .56ga1. of petrol per effective train mile. The average loaded wagon mile per day per effective was 4.25.
With the advance in Sept. 1918, light railways were of great assistance in getting forward ammunition and evacuating the wounded. They were joined on to the German 6ocm. railways which had not been destroyed, but they were soon left behind and the armies relied entirely on the standard gauge railways and road transport. Light railways, when worked to their maximum capac ity, carry, on an average, about 14o tons of supplies per mile of track per day, according to the grading of the line, and the cost in man-power for operating purposes only, as compared with a standard-gauge railway, is as 3.45 to 1 per mile and cost in man power for construction as 2.2 to 4.7. An extension to light rail ways, known as "foreways," and used for carrying supplies from the end of the light railways up to the trenches, consisted of 6ocm. gauge track laid on an unballasted formation ; the rails
weighing about 9 lb. per linear yard of rail on sleepers weighing 8 lb. and spaced 3ft. apart, centre to centre; on these lines flat topped, four-wheel trollies were pushed by two men during the night right up to the communication trenches. Early in the war the armies objected to these foreways being laid with steel rails, urging that the noise of steel wheels grinding on steel rails would attract enemy fire. The first of these lines were, in consequence, made of pitch-pine rails nailed on to wooden sleepers ; but the friction between steel wheels and wooden rails was so great that the trollies were continually being derailed. (D. L.) American Practice in the World War.—The American light railways were 6o-cm. gauge like those of the French, British, Italians and Germans. The service of the narrow gauge lines began at the standard gauge railheads, up to which point the transportation of munitions and supplies was carried out by standard gauge railways and canals. At the railheads or corre sponding canal heads transfer was made either directly or after storage to the equipment of the 6o-cm. lines. The light railways were extended very nearly to the front line trenches, and they were constructed, maintained, and operated by special regiments as signed to the light railway service. Regimental headquarters com bined the functions of military control over light railway personnel and the management of railway lines in a given sector. Motive power consisted of steam locomotives, 4-cylinder geared gasoline locomotives of 5o and 35 h.p. and small trench gasoline locomo tives.
A central assembly and repair shop for light railway equipment was established at Abainville (Meuse), and comprised 70,000 sq.ft. of buildings, including an erecting shop, smith shop, machine shop, foundry, gasoline engine repair shop, car shop, oil house, power plant, storehouse, and carpenter shop. The largest number of American light railway troops engaged at any one time was between Sept. 15, and Nov. 9, 1918, when the number rose to 13,65o. The daily net tonnage handled by narrow gauge lines operated by the American Expeditionary Force was 8,1oo tons in Oct. 1918. It was found that the average progress in the con struction of new line was at the rate of 3 ft. of completed track per man per day. An average of 2.2 men per km. was required for maintenance of way. Contrary to the British and French practices, the Americans lengthened the usual haul of freight in certain cases far beyond anything previously considered prac ticable for 6o-cm. army lines. The average for the entire American light railway operation was 15.2 km., which is about 30% above British or French practice. On Nov. io, 1918, the American light railways were operating 623 km. of main line, with a personnel on operation alone of 57 officers and 3,557 men. The total of tonnage handled by light railways from the commencement of operation to Feb. 1, 1919, was 860,652. (G. B. T.)