2 BULLETIN 463, U. S. DEPARTMENT OF AGRICULTURE. 



the issuance of this bulletin, the aim of which is to supply reliable 

 information concerning the construction and maintenance of earth, 

 sand-clay, and gravel roads. 



LOCATION AND DESIGN.* 



Since nearly all public roads are laid out originally as earth roads, 

 and since the original location and design usually have such an im- 

 portant bearing on all subsequent improvements, it seems well to in- 

 clude in this bulletin a brief discussion of the fundamental principles 

 underlying the proper location and design of a public road. But, 

 before undertaking such a discussion in detail, it is desired to em- 

 phasize the all-important facts that for a particular road the best 

 and most economical location depends largely upon individual judg- 

 ment, and that well-balanced and experienced judgment regarding 

 the relative importance of the various details involved is a much more 

 valuable asset in undertaking to locate a road than mere technical 

 skill in handling surveying instruments. No knowledge gained from 

 books alone can give that complete grasp of the relations existing 

 between a public road and the community it serves which is so neces- 

 sary if the location and design of the road are to secure the greatest 

 possible good from the money expended. 



In locating or relocating a public road the prime considerations 

 should be, first, the comfort and convenience of the traveling public 

 which it is intended to accommodate; and, second, the economy of 

 public funds. The first consideration fixes the general location of 

 the road and limits such details of design and layout as affect the 

 safety and comfort of travelers. The second should control the 

 detailed working out of a location to suit the topography or surface 

 layout of the region through which the road passes, with due regard 

 for such features of the design as affect the cost of construction, of 

 maintenance, and of hauling over the completed road. 



The comfort and convenience of travelers require, first, that the 

 road pass conveniently close to the dwelling places of those for 

 whose particular use it is built; second, that it be free from dan- 

 gerous curves and grades and sufficiently wide for safe travel; 

 and, third, that the surface be such as to remain reasonably firm 

 and smooth and to become neither very dusty nor very muddy under 

 any combination of weather and traffic conditions. The extent to 

 which any particular road must meet these requirements depends, of 

 course, on the state of public sentiment in the community which pays 

 for the road. But in most communities it is safe to assume that the 

 standards of excellence as regards the accommodation demanded of 



1 This section has been read and revised by P. St. J. Wilson, chief engineer, and T. War- 

 ren Allen, general inspector, U. S. Office of Public Roads and Rural Engineering. 



