Until 1855 all rails were made of wrought iron, but in that year steel rails were rolled in Eng land, and were laid in track. Steel rails were rolled experimentally in the United States in 1865 and in 1867 they were being rolled to sup ply orders from the railways. The substitution of steel for iron for railway rails was one of the benefits wrought by the invention of the Bessemer process of steel-making. (See IRON AND STEEL. ) The Bessemer process was introduced and devel oped in America largely through the efforts of A. L. Holley (q.v.). It has been claimed with pubstantial justness that no other invention did so much to encourage the development of the heavy-traffic, high-speed American railway as did this epoch-making discovery of Bessemer. In America and England rails are now- generally spaced 4 feet inches apart, this spacing be ing known as the standard gauge. Various other gauges are employed in other countries, the meter gauge, 39.37 inches, being common in South American countries and Japan, a 5 foot 6 inch gauge being used in India. and a 5 foot 3 inch gauge being used in Ireland. A narrower gauge than the meter gauge has been employed on some railways. The Great Western Railway in England was originally constructed with a 7 foot gauge, and it wa,A not until 1S92 that it was converted to a standard-gauge road. A 6 foot gauge was introduced on the Erie Railway and retained long after the standard gauge had become general in the United States. As time pas.se+,, however, the 4 foot inch gauge is becoming more common all over the world. The method of fastening rails to the ties varies. in America hook-headed spikes are almost universally used; the bull headed rail used in England is wedged into cast iron chairs which are bolted to the ties; in Europe considerable use is made of bolts; and when steel ties are employed various forms of clamping devices tightened by means of bolts or wedges are used. To allow for expansion, rails are usually laid with a little space between the ends of succeeding rails. The space allowed varies on different roads and with the tempera ture at the time the rail is laid, but it is sel dom more than three-eighths of an inch for the coldest weather and from this distance it gradually decreases to nothing at the maximum prevailing heat for the climate which the road has to endure.
The ends of succeeding rails are clamped to gether by various devices going under the general name of rail joints. The simplest form of rail joint is the fish plate, and the most common form is the angle bar. (See FISH PLATE.) The joint remains the weakest point of the rail despite all the efforts which have been made to remedy this weakness. It may be noted in passing that these efforts are responsible for the numerous forms of patented rail joints which are on the market, several of which have met with substantial suc cess. Rail joints are defined as suspended when the opening between the rail ends comes over the space between the adjacent ties, and as sup ported joints when this opening comes over the centre of a tie. Suspended joints are by far the most common in the United States. Rails are said to he laid with square joints when the joints of the two lines of rails are opposite each other, and they are said to be laid with broken joints when the joints in one line of rails come opposite the centre portion of the rails in the other line. . Broken joints are the more common in the United States. On curves the gauge of the rails is usually slightly increased, with the idea of preventing the flanges of the car wheels from binding when rounding curves, and the outer rail of the curve is elevated above the level of the inner rail to counteract the tendency of the running cars through centrifugal force to continue in a straight line when passing a curve.
and on sharp curves braces of stamped or cast steel or iron are spiked to the tic and brace against the side of the rail. These braces are
called rail braces. In many places rails develop a tendency to creep or travel along the track, due to the various forces acting upon them. The di rection of this creeping may be either up or down grade, with Or against the traffic, and to prevent it check plates or creeper plates are sometimes employed, which are bolted to the rail and spiked to the tie. Special forms of track construction are required at switches.
The switch is a device by which a train is di rected from one track to another. An essential part of a switch is a frog. (See FROG.) On bridges and trestles the track construction also varies somewhat from that on embankments and in cuts. Sometimes the floors of bridges are made solid and carry ballast on which the ties and rails are supported in the usual manner, but more commonly the ties are laid on the bridge stringers and carry the rails without any ballast. An essential part of railway track on bridges is a wooden or metal rail laid parallel to each of the track rails and a little distance away from them. The object of the guard rails is to restrain the free movement of derailed cars and prevent them from running off the bridge. In thickly settled districts the railway right of way is usu ally fenced in with fences of timber or wire, or, where a nice appearance is particu larly desired, with hedges and walls of stone bearing orna mental iron railings. At grade crossings of highways and in a few other places at • which cattle are liable to stray onto the track cattle guards are employed. These are of two kinds, known as pit guards and surface guards. A pit guard, as its name implies, is a wide deep pit underneath the rails which cattle will shun for obvious reasons. A surface guard is made up of sharp edged or toothed slats of wood or metal which depend for their efficiency upon the fact that in treading upon them the animal The amount of this elevation is greater the sharper the curve is. This same centrifugal force of the car tends to push the outer rails of curves in an outward direction or away from the inner rail, and to prevent this the outside rails on flat curves have a double set of outside spikes, hurts its feet and withdraws from the attempted crossing.
Sidings and yards are special developments of the track system for special purposes. Sidings are provided to enable trains to pass on single track roads and to relieve traffic on double track.
Yards are aggregations of tracks at terminals and other points which are provided for the stor age and handling of ears which accumulate at those points. Various arrangements of yard tracks are employed, each arrangement being adopted to serve certain purposes and to meet certain conditions of traffic and of form and area of yard space. At the ends of stub tracks a bumping post (q.v.) is a necessary structure to prevent the cars from running otf the end of the track. Another essential structure is a turntable for turning locomotives and some times cars. Track scales are an important item in railway-yard equipment. They resemble very closely the familiar platform scale used for weighing hay, coal, etc., in wagons, but are much larger and stronger so as to accommodate heav ily loaded cars. To facilitate the handling of locomotivos ash pits are provided into which the engines may dump their grates when necessary, and also water tanks, as are shown in the illus tration. Station platforms are also usually classed as a part of the track construction.
So far reference has been made only to track construction, but track maintenance is quite as important an item. The work of maintaining the track of railways in good order costs in America all the way from $500 to $1500 per mile, and is from S to 20 per cent. of the total operating ex penses. The number of employees engaged in track work by American railways averages about 150 per 100 miles of line.