TRAMWAY. A track or line of rails laid down in the public roads or streets (hence the United States equivalent "street rail way") along which wheeled vehicles are run for the conveyance of passengers and, occasionally, of goods; also a light roughly-laid railway used in coal mining and for carrying out public works.
Construction.—The earliest form of construction consisted of primitive lines or trams of wood or flat stones. Later, in 1676, the longitudinal timbers forming the rails were laid on transverse logs and provided with a stout capping of beech or sycamore to facilitate easy renewal of worn sections without undue disturbance of the understructure. In 1767 iron plates were substituted for the wood capping; and early in the 19th century iron rails were used.
The first tramway or street railway intended for public pas senger traffic was the New York-Harlem line opened in 1832. The rails had a deep wide groove which proved so dangerous to the ordinary light narrow-tyred vehicles of the period that they had soon to be removed. Twenty years later Loubat, a French engineer, devised and used a wrought iron rail with a narrower groove and with a clearance suitable for wheel flanges. In 1855-6 Charles L. Light, an English engineer, designed a rail with a groove limited to in. in depth and carried up to the surface with a slight slope for a tramway in Boston, U.S.A. No form of grooved rail, however, seemed to suit the conditions of local traffic in the United States, and an entirely different kind of rail was introduced and used in the construction of a tramway in Philadelphia. This consisted of a flat rail 5 in. wide, with a step at one side raised in. above the surface. It was made of wrought iron and weighed 50 lb. per yard.
Loubat in 1855 laid down a tramway in Paris—the first of its kind in Europe. It was a replica, in most respects, of his New York form of construction. The rail was 3 in. wide on the surface and had a groove 14 in. wide ands in. deep, with a tread ik in. wide. It was of a semi-hexagonal section at the lower side, to rest upon a timber sleeper which was chamfered to receive it, and upon which it was spiked diagonally through the sides. A fishplate of iron, 6 in. long and in. thick, was laid under each joint. The rail weighed 19 kg. per metre or 38 lb. per yard. The tramways first constructed by G. F. Train in England in 186o-3 had a step
rail of the Philadelphia pattern. This rail was manufactured of wrought iron and weighed 5o lb. per yard. It was 6 in. wide and had a step 4 in. above the sole. The rails were spiked to longi tudinal timbers laid on transverse sleepers. English people, unlike the American, would not however tolerate the danger and obstruc tion caused by the step rail, and the tramways in London had to be removed after a brief period of working, while those initiated by Train at Birkenhead and in North Staffordshire were preserved by the timely substitution of a flat grooved rail.
The adaptation of the steam locomotive for street tramway purposes necessitated tracks of greater strength and rigidity than were sufficient for horse traction. The older methods of supporting the rails were inadequate for stability, and many attempts were made to overcome the difficulty. Finally recourse was had to the girder rail which soon proved its superiority to the built-up rail, and it eventually became predominant in tramway construction. A form of girder rail was patented in 186o by Charles Burn ; reinvented and patented in 1877 by Achille Legrand of Paris; and with modifications again patented in 1878 by J. Gowans, who succeeded in establishing its greater merits after the lapse of 20 years from the time of its original inception.
The method of construction of modern street tramways fol lows the same general principle in all countries; variations de pending upon local conditions which govern the depth of the con crete foundations, weight and composition of the rail, and the class of paving. In cities the foundation consists of six or more inches of concrete. The rails weigh about no lb. per lineal yard, and are of 45 ft. or 6o ft. in length, according to require ments. Heavy fishplates are used for the joints of the rails or the rail ends are electrically welded together. Steel tie-bars are interposed at short intervals and, where electric traction is the motive power, the rails are bonded together by copper rods to provide a continuous path for the return current (and to prevent leakage and consequent possible electrolysis of contiguous pipes). The surface of the rail is laid flush with the paving which may be of wood blocks or granite or basalt setts, grouted with cement.