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



cross sections shown in figures 2 and 3 have the advantage in that 

 they may be constructed with an ordinary road grader, which is not 

 true of the section shown in figure 4. 



3. Where it is impracticable to construct side ditches that will carry 

 the required amount of water without washing, paved gutters should 



SIDE DITCH 



S/opeTj/L 



ROADWAY I 



Fig. 4. 



be employed. Suitable cross sections for a cobble gutter are shown 

 in figures 5 and 6. Where it is impracticable to construct gutters, 

 earth side ditches frequently may be kept from washing by the use 

 of breakers (figure 7). 



<4k COBBLE GUTTER 



Slope I'^l^r- — 



ROADWAY 



Cobbles- hard, round stone G"to 10" longest' 

 f\ diameter. 

 ,r T Sand bedding about 2" thick. 



Foundation of gravel or broken stone. 



Fig. 5. 



4. If the material composing the roadbed consists of springy 

 earth, some form of underdrainage is essential. A line of farm tile 

 laid to proper grade under each side ditch is, in general, the most 

 satisfactory way of securing adequate underdrainage. Either 4-inch 



COBBLE GUTTER 



__ ROADWAY_ 



Cobbles- hardTround 

 10" longest diameter. 



Sand beading about 2" thick. 



Foundation ofgravel or broken 

 stone. 



Fig. 6. 



or 6-inch tile is employed for this purpose. Figure 8 illustrates the 

 customary method of constructing tile drains. 



5. Culverts or bridges should be constructed wherever it is neces- 

 sary to carry water across the road. No rules regarding the plan- 

 ning of these structures can be given here. 



