HKJIIWAY CONSTRUCTION :',7 



road. If this is not sufficient the road heroines flooded during hea\y 

 rainstorms and melting snow, and is considerahly damaged. 



The removal of surface water from country roads may he effected 

 by the side ditches, into which, when there are no sidewalks, the 

 water flows directly. When there are sidewalks, gutters are formed 

 between the roadway and footpath, as shown in Figs. 13 to 17, and 

 the water is conducted from these gutters into the side ditches by 

 tile pipes laid under the walks at intervals of about />() feet. The 

 entrance to these pipes should be protected against washing by a 

 rough stone paving. In the case of covered ditches under the footpath 

 the water must be led into them by first passing through a catch 

 basin. These are small masonry vaults covered with iron gratings to 

 prevent the ingress of stones, leaves, etc. Connection from the 

 catch basin is made by a tile pipe about inches in diameter. The 

 mouth of this pipe is placed a few feet above the bottom of the catch 

 basin, and the space below it acts as a depository for the silt carried 

 by the water, and is cleaned out periodically. The catch basins may 

 be placed from 200 to 300 feet apart. They should be made of 

 dimensions sufficient to convey the amount of w r ater which is liable 

 to flow into them during heavy and continuous rains. 



If on inclines the velocity of the water is greater than the nature 

 of the soil will withstand, the gutters will be roughly paved. In all 

 cases, the slope adjoining the footpath should be covered with sod. 

 A velocity of 30 feet a minute will not disturb clay with sand and 

 stone. 40 feet per minute will move coarse sand. 60 feet a minute 

 will move gravel. 120 feet a minute should move round pebbles 1 inch 

 in diameter, and 180 feet a minute will move angular stones 1 J inches 

 in diameter. 



The scour in the gutters on inclines may be prevented by small 

 weirs of stones or fascines constructed by the roadmen at a nominal 

 cost. At junctions and crossroads the gutters and side ditches re- 

 quire careful arrangement so that the water from one road may not 

 be thrown upon another; cross drains and culverts will be required 

 at such places. 



Water Breaks to turn the surface drainage into the side ditches 

 should not be constructed on improved roads. They increase the 

 grade and are an impediment to convenient and easy travel. Where 



