DRAINAGE METHODS. FOR COUNTY ROADS. 37 
COST OF CONSTRUCTING TILE DKAINS. 
The cost of laying tile drains, including necessary ditching and. 
back filling, varies largely on account of variations in costs of mate- 
rial and labor, as already indicated. Where stone occurs in the ditch, 
or where any other condition makes excavation unusually difficult, the 
cost will be increased substantially. Where the soil is unusually 
soft, it is necessary sometimes to place boards in the bottom of the 
ditch to keep the tile from settling out of line, and in this case the 
cost of laying the tile, including the purchase of the boards, will be 
increased still further. In the rare cases where the conditions are 
such as to make it desirable that the ditch be entirely back filled with 
crushed stone or gravel so that the tile may do its work to the best 
advantage the cost of stone or gravel may be considerable. The addi- 
tional cost of handling such cases would depend, of course, on the 
availability of the materials used in the back fill. In some cases the 
total cost, including all labor and material, has exceeded $50 per 
100 feet, although $10 to $12 per 100 feet are commoner figures for 
ordinary tile drain. 
Blind drairj 
V-Orain constructed of field stone- or gravel wnere foundation is defective. Outlets to side ditches every 50 feet 
Ditches to be of sufficient depth to drain V-drain 
V- DRAIN 
Fig. 13. 
Suitable head walls and outlets for tile drains may be constructed 
at small cost. The design shown in figure 12 ordinarily can be built 
at a cost not to exceed $5 or $6. In some cases stone masonry may 
be employed at even a smaller cost. 
V -DRAINS. 
The V-drain shown in figure 13 and Plate V is especially adapted 
to localities where field stones can be obtained cheaply and in abund- 
ance. This type of drain is very effective when constructed properly 
and has the advantage that in addition to draining the subgrade of 
the road it provides an excellent foundation for the road surface. Its 
first cost is high when compared with the various types of side drains, 
but usually is much lower than the cost of side drains and Telford 
foundation combined. The latter comparison is, in general., the more 
reasonable one to make, because under favorable conditions a V-drain 
may serve to replace the combination of Telford foundation and side 
drains, and would be used seldom, if ever, where only drainage is 
needed to produce a stable foundation. 
