EARTH, SAND-CLAY, AND GEAVEL ROADS. 5 



In mountainous regions, on the other hand, the problem may be to 

 fit the road to the contour of the country, regardless of land lines, 

 cultivated fields, and all other considerations except grade, drainage, 

 and line. Plate I, figures 1 and 2, illustrates methods of solving 

 some common location problems where the lay of the land, or topog- 

 raphy, was an essential consideration. 



In general, the proper location and design of a road involves: (1) 

 determining its controlling points; that is, fixing its general route 

 with reference to certain points which the road must pass through, 

 (2) surveying a route which passes through the controlling points 

 and is otherwise adapted to the lay of the land, (3) a study of the 

 drainage situation, (4) preparing such plans and drawings as are 

 necessary for proper construction and a complete record. 



CONTROLLING POINTS. 



Such features of the locality as gaps through ridges, exposure to 

 the sun, narrow stream crossings, and suitable points for crossing 

 railroads (preferably by means of overhead bridges or under passes) , 

 together with the necessity for connecting up with certain centers of 

 population, usually will serve to fix the location of a road within 

 fairly definite limits. For important roads these controlling points 

 are determined by careful inspection of all possible routes. 



THE SURVEY. 



The care which should be exercised in making a road survey neces- 

 sarily must depend upon the importance of the road and the amount 

 to be expended in its improvement. An ordinary farm road, for 

 example, usually requires no survey other than lining it by the eye 

 between the controlling points. Some unimportant public roads 

 may require very little more than farm roads in the way of a survey, 

 but if any considerable amount of grading or other work is to be 

 done, either at the time the road is located or later, the survey 

 should include all instrument work necessary to insure that the work 

 will be done economically. 



The purposes of a survey are (1) to determine accurately the 

 topography or lay of the land so that the location may follow the 

 route which presents the fewest obstacles, (2) to fit the grade line 

 to the ground surface so as to keep down the amount of grading 

 necessary, (3) to balance cuts and fills so that whatever grading is 

 done will be to the best possible advantage, (4) to line up the road 

 and provide stakes for controlling the work, (5) to obtain data from 

 which proper plans may be prepared and an estimate of cost made, 

 (6) to provide a record that will prevent subsequent contentions 

 among landowners regarding the original location of the road. 

 While the importance of all these purposes is apparent, frequently it 



