3 RAILWAY CONSTRUCTION. 



scale as to compel long detours in the formation of a more 

 suitable opening; and in others, although the difficulties are 

 not insurmountable, they may involve works of great magnitude 

 and expense. 



In a comparatively rich country, with a prospect of large 

 and remunerative traffic, a succession of heavy works, bridges, 

 and tunnels may be admissible and expedient; but in new 

 countries economy of outlay has to be considered, and costly 

 works avoided as much as possible. 



Every one of the heavy works on a line, whether lofty 

 bridges, long viaducts, or costly tunnels, not only enormously 

 increase the original expenditure of the undertaking, but also 

 entail large annual outlay in the necessary constant supervision 

 and maintenance. , 



Each particular scheme will have to be discussed on its own 

 individual merits. The heavy, high-speed passenger traffic line 

 will suggest light gradients and easy curves, while on secondary 

 lines and in thinly populated districts it may be prudent, for 

 the sake of economy, to introduce sharper curves and heavier 

 gradients. Even in the latter case, and especially in new 

 countries, it is well to keep in view the future possibilities of 

 the undertaking. The steeper the gradients, the greater the 

 cost and time in working the traffic, and if there is every 

 probability of early and large development, the prospective 

 increase may warrant an additional outlay in the original 

 construction. 



Large, open plains and wide valleys of important rivers 

 generally afford ample latitude for the selection of a suitable 

 route, and, by taking advantage of the gradations of altitude, 

 a favourable course may be adopted without incurring excessive 

 gradients. When traversing moderately hilly districts, some 

 low ridge or opening may be found, which may form a pass 

 from the one side to the other, and the line may be laid out for 

 a long distance to lead gradually up to the highest point. But 

 when a route has to be laid out over some of those lofty 

 mountain ranges which are met with abroad, the locating of 

 a suitable line, or of any line, becomes particularly intricate and 

 difficult. A comparatively low ridge may be found possessing 

 features in favour of the project, but the question will be how 

 to reach that point. The nearer the summit of these high 

 mountains, the more precipitous the sides; no one slope can 



