_Varrozo Gauge.—There is in all parts of the world a considerable num ber of railroads of narrower crano-e than the standard. In the United States there are thousands of miles of such roads, principally, however, short lines and in new or thinly-settled districts. As such roads can be constructed, equipped, and operated cheaply, they may often profitably be maintained in regions where more costly roads of standard gauge and equipment would prove unremunerative. They are found specially ser viceable for the transport of crude materials, such as ores, building-stone, lumber, etc. To avoid the delay and expense of removing freight and passengers from the cars fitting one gauge of road to those fitting another gauge, the car-transfer apparatus devised by Ramsey has been adopted to a large extent in the United States. (See p. 2o7.) Other Considerations in Planning a Road.—Besides the points above mentioned in connection with the location of the projected railroad, other subjects are important to consider, such as the future division of the road into sections, the location of stations, the power of the engines, the con struction and carrying- capacity of the cars for the several forms of service, etc. The engineer of the projected road must have a clear conception of the objects that its projectors have in vie.w, in order that its location, con struction, equipment, etc., shall be such that these objects may be attained in the most effective manner and with the least expenditure.
Selection of same general principles that govern the choice of a route for a roadway should also govern the selection of a route for a railroad. The standard of perfection is a perfectly straig-ht and level road bed for the reception of the permanent way. In his endeavor to approxi mate to this standard the engineer will be confronted with many difficulties that will demand the exercise not only of technical skill, but also of sonnd business judgment, properly to overcome them. The introduction of many
and sharp curves and of steep gradients, while most objectionable because they involve extra cost for maintenance and operation, may be found de sirable, because they may save considerable in the first outlay. This will be the case when to avoid them will necessitate excessive outlay for cut ting, embanking, and tunnelling. It is the task of the engineer to give due consideration to all the conditions affecting-, the problem. Engineering advantages will occasionally have to be sacrificed to financial objections, and vice versa,. so that the route filially adopted must be a compromise to expediency. While the railroad may not be quite straight or quite level, it must not be excessively costly by reason of extravag-ant outlay for em bankments, cuttings, and tunnels to avoid sharp curves and steep gradi ents; nor must everything be sacrificed to cheapening the first cost of the road by avoiding- such features of construction where they should properly be employed, as such saving would often be more than counterbalanced by the increased expense for operation.
Prefiaratory technical preparatory work beg-ins with the selection of the general direction of the proposed road. The region is critically examined with the aid of a good map, the positions of the water courses and summits are determined, the most advantageous points for bridging the former and crossing the latter are decided. Experimental lines are then run between the points thus located. The adjacent territory on both sides of these lines is carefully gone over, and from the comparison of the data thus collected and collated the route is selected. When this has been determined, the ground is surveyed with accuracy, the road is staked off, longitudinal and cross-sections are prepared, the projected line is drawn to scale, and the exact calculations and estimates of cost are made.