ON AMERICAN PERMANENT WAT. 593 



On American Permanent Way. 

 By Joseph M. Wilson, A.M., M.Inst.C.E. 



[A communication ordered by the General Committee to be printed in extenso 



amoDg the Reports.] 



[Plates VI.— VIII.] 



Thi: word ' American ' covers a very wide field, including not only Canada 

 and the United States, but the whole continent : a vast extent of country, 

 ■with all its varying conditions of climate, of constructive material, and of 

 railway requirements. 



When, therefore, American Permanent Way comes to be considered, 

 the subject must necessarily involve a considerable variety of construc- 

 tions, depending upon location and other conditions. Thus the form of 

 construction required for a railroad in the Northern United States or in 

 Canada, built to resist the severe winters of these latitudes, might be 

 unnecessarily expensive for the mild climate of the south ; also roads with 

 heavy traffic require a more solid and substantial construction than those 

 having only a light service ; then, again, the materials of construction 

 available in places geographically far apart are often very different, and 

 the engineer must adapt himself to circumstances, using what materials 

 he can best obtain at a reasonable cost. 



Permanent Way, or railway superstructure, as it is sometimes called, 

 is that portion of railway which directly receives the weight of the 

 moving trains, and transmits it to the road-bed below. It comprises the 

 rails, the cross-ties or sleepers to which these are attached, and the dis- 

 tributing material in which the ties or sleepers are bedded. The object 

 of the permanent way, no matter how constructed, is in all cases the same 

 — to provide a way for the running equipment of the road to move upon, 

 and to so transmit and distribute the weight from this to the substructure, 

 that the latter, which is usually a soft material, as earth, may be able to 

 sustain the load without settlement. 



American Permanent Way only differs from that of other countries in 

 the adaptation of the materials available for the construction of the work, 

 taking into consideration their relative abundance and value, and dis- 

 playing, perhaps, some of the aptness for which Americans have a 

 reputation. 



It is necessary for a first-class perfect track to have good surface, 

 good drainage, true line, accurate gauge, and tight joints. 



Rails have been made of wood, iron, and steel. Wood is so soft a sub- 

 stance, and so perishable, that it can only be employed for very light 

 and temporary service, such as is sometimes required in lumber regions. 

 It has been so employed, and may be considered as essentially ' American.' 

 Iron and steel are the materials used throughout the woiid for railway 

 service proper, and the cost of steel in late years has so nearly approached 

 that of iron, that with its vastly superior qualities it is rapidly driving 

 iron out of use ; in fact, the use of iron may already be said to be of the 

 past. The shape and weight of the rail is governed by several conditions. 

 Its section must be so formed at the top as to properly cany the wheels of 



1884. q q 



