As the portion of the streets or public roads along which the tramway has to be laid will, in all probability, have to be occupied and traversed by all kinds of vehicles besides the tram-cars, it is absolutely necessary that the permanent way for the tramway should be of such description as to require the least possible amount of adjustment of fastenings or opening out of the roadway for repairs. Where the entire width of the street, including the space between the tram-rails, is paved with stone setts, the opening out of even a short length for repairs is tedious and costly, and causes considerable obstruction to the street traffic. It is most important, therefore, that the rail and its fastenings should not only be strong enough for its own tram service and the carts and drays which will pass over and across the track in all directions, but it must possess the minimum necessity for disturbance.
[Figs. 275 to 279] are sketches of a few of the many types which have been brought into use in various places.
Where the public roads are wide, and a space can be set apart at the side for the special use of the tramway, the arrangement shown in [Fig. 275] will be simple and efficient. It is very similar to an ordinary railway permanent way with the ballast filled in flush with the top of the rails. The rails are shown as flange or flat-bottom rails, fished together at the joints, and properly secured to transverse sleepers of wood, iron, or steel. The space between and outside the rails is filled in with small-sized broken stone ballast or good clean gravel, and forms an even surface, over which animals or cattle may pass without risk of being thrown down.
[Fig. 276] represents a system which was laid down extensively,
especially for horse tramways, but not proving efficient, has been superseded by other types of a stronger and more durable description. The rail was rolled with a continuous groove to provide clearance for the flanges of the car-wheels, and the sides of the rail were turned down so as to fit over the longitudinal timber sleeper, to which the rail was secured by staple-dogs, as shown. Cast-iron chairs, spiked on to wooden cross-sleepers, held the longitudinal sleepers in position. The wooden sleepers were favourable for smooth running, but the section of the rail, practically a light channel-iron laid on the flat, was most unsuitable for carrying weight or for making a proper joint. Experience proved this road to be very difficult to maintain in good order for easy traction. The staple-dogs worked loose after a little time, and the rail, having scarcely any vertical stiffness, rose and fell during the passage of every car-wheel, resulting in most uneven joints and a clattering roadway.
With the view to obtain a stronger and more permanent support for the rail than the longitudinal timber sleeper last described, various forms of cast-iron chairs were devised. [Fig. 277] represents one of these patterns. The rail, which is of T-section with a continuous wheel-flange groove, is secured to the cast-iron chair by the cross-pin, as shown. Although this cross-pin may in time work a little loose, it cannot work out, being kept in position by the paving-setts on each side. The cast-iron chairs are placed at convenient distances, and being set in a bed of concrete, do not require cross-sleepers or tie-bars. This type makes a strong road, but the rail-joints cannot be made so even or efficient as with the more modern form of rail.
Rail manufacturers are now able to roll a section of rail combining the vertical stiffness of the ordinary flange, or flat-bottom, rail with the running-head and continuous wheel-flange groove, considered the most suitable for heavy tramway traffic. The introduction of this section of rail has contributed greatly to the increased efficiency and durability of the permanent way for street traffic; and as the ends of the rails can be secured by ordinary fish-plates, there is the great acquisition of even joints and increased smoothness in the running of the tramcars. This rail can be rolled of various weights to suit the rolling loads. On some tram-lines a moderately heavy section has been adopted, and secured to transverse sleepers of rolled iron or steel laid on a bed of concrete. On others similar rolled metal sleepers have
been used, but laid longitudinally. For some descriptions of traffic a much heavier section of rail has been used, having a base sufficiently wide to provide ample bearing on a bed of concrete without the intervention of either transverse or longitudinal sleepers.