12 HIGHWAY CONSTRUCTION 



LOCATION OF COUNTRY ROADS, 



The considerations governing the location of country roads are 

 dependent upon the commercial condition of the country to be 

 traversed. In old and long-inhabited sections the controlling ele- 

 ments will be the character of the traffic to be accommodated. In 

 such a section, the route is generally predetermined, and therefore 

 there is less liberty of a choice and selection than in a new and sparsely 

 settled district, where the object is to establish the easiest, shortest, 

 and most economical line of intercommunication according to the 

 physical character of the ground. 



Whichever of these two cases may have to be dealt with, the same 

 principle governs trie engineer, namely, to so lay out the road as to 

 effect the conveyance of the traffic with the least expenditure of 

 motive power consistent with economy of construction and main- 

 tenance. 



Economy of motive power is promoted by easy grades, by the 

 avoidance of all unnecessary ascents and descents, and by a direct 

 line; but directness must be sacrificed to secure easy grades and to 

 avoid expensive construction. 



Reconnoissance. The selection of the best route demands 

 much care and consideration on the part of the engineer. To obtain 

 the requisite data upon which to form his judgment, he must make 

 a personal reconnoissance of the district. This requires that the 

 proposed route be either ridden or walked over and a careful examina- 

 tion made of the principal physical contours and natural features of 

 the district. The amount of care demanded and the difficulties 

 attending the operations will altogether depend upon the character 

 of the country. 



The immediate object of the reconnoissance is to select one or 

 more trial lines, from which the final route may be ultimately deter- 

 mined. 



When there are no maps of the section traversed, or when those 

 which can be procured are indefinite or inaccurate, the work of 

 reconnoitering will be much increased. 



In making a reconnoissance there are several points which, if 

 carefully attended to, will very considerably lessen the labor and 

 time otherwise required. Lines which would run along the imme- 



