46 



TRANSPORTATION ON LAND BY VEHICLES: -THE ROADS 



cross profile of each point is sketched on cross section paper. In this case, different scales, for the heights 

 and for the widths entered on the paper, are not permissible. 



Then, into the actual cross profile, is entered the "norma! cross profile" of the road, exhibiting its 

 upper and lower slope, the ditch, and the crown of the road. 



For each section point, from this sketch, is ascertained the sectional area of dirt to be filled in or 

 to be cut out. The sectional areas are ascertained: — 



1. By dividing them into triangles and trapezes; or 



2. By counting the number of squares on the paper, or with the help of a glass plate on which 

 the units of measurement are engraved ; or 



3. With the help of a planimeter; or 



4. With the help of the trigonometric functions of the actual natural slope and of the artificial side 

 slope of the road. 



Auxiliary tables are constructed which show, for given slopes, given widths of road and given depths, 

 directly the sectional areas of the profiles in cuts and fills. 



SECTIONAL AREAS OF CROSS PROFILES OF CUTS AND FILLS 



