Handrails are made of concrete, structural steel, gaspipe, or timber. The concrete rails are the best looking, but are also the most expensive. Contrary to the general ideas of engineers, they will require repairs from time to time, in order to replace chips broken off from the sharp edges of columns by blows, or, by spalling in the case of concrete placed in cold weather and not thoroughly protected against freezing.

Steel handrails are expensive, when substantial; and they require painting from time to time.

Gas-pipe handrails are flimsy in appearance and ineffective besides.

Timber handrails are the cheapest, but like all other timber construction in bridges they are objectionable because of fire—besides, the ordinary ones are inherently ugly.

Electric-Railway Tracks

With timber decks the problem of caring for the electric-railway tracks is a simple one, but with a permanent deck it is somewhat difficult, involving, as it does, some economic considerations. In the. first place, the rails must be of a height to suit the pavement adopted, and their heads must be flush with the top thereof. Next, the best method of support is a knotty point to solve. For a concrete deck there can be employed timber ties surrounded with either ballast or concrete, or steel ties embedded in concrete, or steel ties embedded in the reinforced-concrete slab and resting directly on the steel stringers, or steel rail-chairs supported in a similar manner. When the roadway and the railway are separated so that the two kinds of traffic cannot mingle, any of the types of floor previously described for steam railways can be used. The wooden ties are generally the least expensive type of track, and steel ties in a concrete base are costly. Steel ties in the reinforcing slab and resting directly on the steel stringers make good construction, especially for long-span bridges. Steel chairs are cheaper and fairly good, but they do not ensure a perfect spacing of the rails. Wooden ties in ballast are cheap per se, but the construction is heavy, and, therefore, expensive for all but very short spans.

Floor-Systems

The arrangement of the floor-system, i.e., stringers, joists, floor-beams, and cross-girders, with their bracing, depends upon both the type of deck adopted and the kind of span employed.

In I-beam spans there is no need for a floor-system, because they are so short that a concrete deck is all they require; and its extra weight, as compared with that of the open deck of timber ties, does not add appreciably to the cost, because of the large ratio in any case of live load to dead load. The economical spacing of the I-beams varies from six to ten feet, increasing gradually  with  the  span  length.  The  under-clearance,  however,  may  be