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/openL 
ROADWAY ~~] 
tMsmmtrnzmmmzzz. 
U-W-H 
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). 
COBBLE GUTTER 
Slope l"' l 
ROADWAY 
vww/y/M 
Gobbles- hard, round stone 6"to 10" longest 
lo\ diameter. 
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 
round stone 6 to 
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. 
