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 203 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. Fig. 278 is a sketch of the modern rail as laid down on a rolled steel transverse sleeper, the rail being held in position either by turned-up clips, wedges, bolts, or any of the devices in use for similar duty in the rolled-steel sleepers for ordinary railway permanent way. Fig. 279 shows a modern rail of a heavier section, with a wide flange resting direct on a continuous bed of concrete. The gauge is maintained by bar-iron tie-bars placed vertically so as to fit in between the courses of the paving-setts, the ends being forged and screwed to pass through holes in the vertical web of rail, and secured in position by nuts. Both in this, and in type Fig. 278, ordinary fish-plates are adopted at the rail-joints, as indicated by dotted lines. In the last two examples above described all the materials are of the most durable description, and the least liable to wear or decay, but it will be necessary to guard against making the fastenings and the bars too light for the duty they have to perform. There should be ample material in the head of the rail to allow of a fair wearing down, and the continuous flange groove should be sufficiently deep to meet this wearing away without causing the wheel-flanges to strike the bottom of the groove. [Illustration: Fig. 280, 281, 282, 283, 284, 285, 286, 287, 288, 289, 290, 291]