RAILWAY CONSTRUCTION. 359 



moves onward. It is a simple matter to arrange the traffic on a 

 railway when all the works and appliances are appropriate for 

 the service to be performed ; but the advances which are made 

 follow one another so rapidly as to necessitate constant study 

 and organization to effect the structural alterations and additions 

 requisite to maintain an up-to-date standard of efficiency. The 

 traffic manager on a railway receives his instructions from the 

 directors or controllers of the company as to the working out of 

 the train service, rates, charges, and other items of his depart- 

 ment, but the engineer has to stand alone, and his technical 

 knowledge and professional skill must enable him not only to 

 design and construct works suitable in character, extent, and 

 strength to the duty for which they are intended, but also to 

 decide when structures are no longer capable of properly sustain- 

 ing the increasing loads brought upon them, and must be taken 

 down and replaced with others of a stronger description. For 

 this reason the engineer must carefully consider every circum- 

 stance and local feature which may influence the design to be 

 prepared ; he must thoroughly investigate the nature of the 

 ground for foundations, as the description when ascertained will 

 frequently determine the class of work to be erected, whether in 

 viaducts, bridges, or buildings ; and in his selection of materials 

 and calculations for strength, he must allow ample margin to 

 meet further increased weights, as well as for natural deterio- 

 ration. 



He should, indeed, go a little further, and as his perceptive 

 ability and training will always enable him the more readily to 

 foreshadow the direction in which improvements or changes are 

 tending, he should study out and be prepared with his schemes 

 to meet the new departures as the requirements gradually arise. 



Strength and efficiency are the leading points which must be 

 always kept in view, and the engineer must never forget that 

 he is solely responsible for the safety of the line and works, and 

 of the public passing over the same. 



