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Street-Railway Track

concrete, construction, pavement, street, rails and ties

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STREET-RAILWAY TRACK.

Track for street railways upon paved streets should be constructed with a view to offering as little obstruc tion to ordinary street traffic as possible, while per mitting the ready operation of the railway. These two points are apt to conflict, as the interest of the railway company in the construction of track is rarely identical with that of the public use of the street.

Any street-car track is objectionable on a paved street, both on account of the increased wear caused to the pavement, and because it forms an obstruction to the ordinary traffic of the street. It is, however, a necessary evil, being required for the convenience of the public, and its detrimental effects may often be greatly lessened by proper attention to the methods of construction employed. On smooth pavements properly constructed track should offer no obstruction to vehicles crossing it, and afford no channels in which the wheels . of vehicles may run and which prevent wheels readily leaving the track.

This requires that the surface cf the pavement be flush with the top of the rail, and that it be laid in close contact with the rail.

It is also important that the method of construction used in both track and pavement be firm and substan tial to prevent unevenness due to the yielding of the track or settlement of the pavement.

Construction of Track. Methods of construction used for street railway tracks are extremely various and opinions differ widely concerning them. When the traffic of the railway and street is light it is gen erally conceded that the most economical method is that of placing the rails directly upon wooden cross ties, as in the construction of steam roads. Where, however, the traffic is heavy the difficulty and ex pense of making repairs becomes great, and the rail way companies commonly recognize the advantage of solid and permanent construction. Several methods have therefore been devised for securing firm support to the rails.

Fig. 41 shows the ordinary method of construction where a concrete base is employed for the pavement and the tie is embedded in the concrete. In this con

struction the track is surfaced up by ballasting in the usual manner under the ties with gravel or broken stone, after which the concrete base is filled in between and perhaps over the ties. The depth of rail is some times made the same as the thickness of the upper layers of pavement, thus bringing the top of the tie even with the surface of the concrete. Thus a six inch rail may-be used with a brick pavement having a two-inch sand cushion as shown in Fig. 42. If the depth of rail be less than this, stringers, as in Fig. 43, or chairs, as in Fig. 44, are necessary to raise the rails to the level of the paving surface. When stringers are employed they are usually connected by cast-iron braces to the cross-ties, and are also bedded and held in place by the concrete base of the pavement. The ties in such case are usually below the concrete. To secure greater stability when the rails are supported by cross-ties a bed of concrete is sometimes placed under each tie and the track is tamped in concrete. This is shown in Figs. 42 and 44. In such construc tion it is usual to make a trench under the tie, fill this with concrete and tamp the tie with concrete, after ward placing the concrete base for the pavement be tween the ties.

On important lines in streets of heavy traffic re pairs to track are often both difficult and expensive, and very rigid and substantial construction is essential to an economical operation of the railway. To secure such construction the wooden ties are sometimes dis pensed with and the rails placed directly upon the concrete. Several methods of construction of this character have been employed. Fig. 45 shows the simplest form, where the rails are placed directly upon the concrete base of the pavement and spaced by iron tie-rods at intervals of six or eight feet. The con crete in this construction is usually made extra heavy in order to adequately support the rails and maintain them at the level of the pavement.

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