50 RAILWAY CONSTRUCTION. 



inevitable, except by incurring enormous works which would 

 not appear to offer any corresponding prospective recompense. 

 In others the curves may be made of easy radius, at a compara- 

 tive moderate extra outlay, if the character of the line and 

 description of traffic to be accommodated will warrant the 

 expenditure. For main through lines, with heavy, high-speed 

 traffic, it is advisable to have the curves of large radius, so as to 

 avoid the necessity of reducing speed when passing round them. 

 Although a high-class fast train may be allowed to run round 

 an 80 chain (5280 feet) curve at almost unrestricted speed, safety 

 demands that there should be a reduction of speed .on curves of 

 40 or 30 chains radius, and a very much greater reduction for 

 curves of 20 chains radius and under. A sharp curve will in 

 some places form a greater check to fast trains than a length of 

 moderately steep gradient on a straight line. In the former the 

 trains running in either direction must slow down for some 

 distance before reaching the curve, round which they should 

 pass at greatly reduced speed, and then some distance must be 

 run before they can attain their full speed again. On the other 

 hand, with arising gradient, on a fairly straight line, the acquired 

 momentum of the train will materially assist in ascending the 

 incline, and although the speed may be slackened as the train 

 advances, there may not be any very great diminution in the 

 running before the gradient is passed, and average level line 

 reached again. A reduced rate of running must be maintained 

 round curves of small radius, for, however substantial the works 

 and permanent way, and however well devised and constructed 

 the rolling-stock, there is an element of danger ever present 

 when passing round sharp curves at anything more than 

 moderate speed. In the great rush for fast through trains this 

 point is very apt to be overlooked, and too little time allowed 

 for the running. Even with the fastest trains on any line there 

 are some portions of the route which must be traversed with 

 greater caution and less speed than others, either on account of 

 sharp curves or of gradients ; and if those who are entrusted 

 with the preparations of the time tables do not possess the 

 technical information necessary to deal properly with the 

 question of relative speeds, there is the strong probability that 

 the programme prepared may be one both difficult and dangerous 

 to fulfil. The spirit of rivalry is a strong incentive to fast 

 running, but prudence and common sense should indicate that 



