24 BULLETIN 724, U. S. DEPARTMENT OF AGRICULTURE. 
the concrete to be mixed in the proportion 1 part cement, 2 parts sand, 4 parts 
crushed stone or gravel ; the gutter to be given a 1 : 2 mortar finish and to have 
a total depth of 6 inches. 
Materials required per square yard of gutter : 
Portland cement, 0.25 to 0.30 barrel. 
Sand,. 0.070 to 0.080 cubic yard. 
Crushed stone or gravel, 0.14 to 0.15 cubic yard. 
Tar paper or bituminous felt, . 
(If the mortar surface is omitted, this would reduce the cost about 5 or 6 
cents per square yard.) 
Third, consider a brick gutter, figure 7, similar in cross section to the cobble 
gutter, the foundation to be of crushed stone or gravel, the paving to consist of 
vitrified paving brick laid on edge with the long dimensions in the longitudinal 
direction and the joints to be filled with Portland-cement grout. 
Materials required per square yard of gutter : 
Foundation, 0.20 cubic yard crushed stone or gravel. 
Sand bedding, 0.055 cubic yard sand. 
Paving, 40 paving brick. 
Grout, 0.03 to 0.04 661 cement, 0.014 to 0.16 cubic feet of sand. 
DROP INLETS AND CATCH BASINS. 
Drop inlets and catch basins are used to conduct water from side 
ditches or gutters into underground drains or culverts. On country 
roads they are used most frequently on side-hill locations where the 
water collecting in the upper side ditch or gutter can be removed from 
the road at intervals by means of a culvert across to the lower side. 
Where the development contiguous to the road is suburban in char- 
acter they may be required by a variety of conditions. Drop inlets 
usually are sufficient for this purpose and catch basins seldom are 
used in country-road work, except where it is especially desirable to 
prevent the silt and other foreign material carried by the water from 
getting into the underground drainage structure. 
Where catch basins or drop inlets are to be used, their location and 
design are of especial importance. It is almost as common a fault, 
however, to omit them as to introduce them improperly into the drain- 
age system. As indicated above, they are used to relieve the upper 
ditch or gutter and therefore have a close relation to the capacity of 
such gutter and its tendency to erode. Rightly placed, they afford a 
means of controlling the amount of water delivered by successive sec- 
tions of gutter to the sections immediately adjacent, and enabling a 
gutter of uniform cross section to be designed for long slopes. In 
handling hillside drainage it is good practice to clear the gutters at 
the crest of the grade. If water has been brought across a flat to the 
top of a hill it is likely that in heavy rains the hillside ditches will 
be overcharged unless relieved at frequent intervals. Culverts placed 
under the road to provide such relief should have some form of in- 
take that will direct w T ater into them. The drop inlet may be used for 
