chapter  Chapter 4
34 Pages

Drainage

WithMalcolm Copson, Peter Kendrick, Steve Beresford

The emphasis in roadwork is, obviously, on storm drainage, but some basic knowledge of foul drainage is needed as the drainage systems will be encountered from time to time in carrying out road building and improvement schemes. Sub-soil drainage must be designed to cope with water in the ground and to ensure that the water table can be kept low enough not to allow saturation of the road structure and its surrounding soil. For new roadworks in urban areas, there is generally an existing storm sewer to which the drainage from the new roads must be connected. The objective in designing a road drainage system is to provide drains/sewers with sufficient capacity to deal with the most severe storm conditions and laid to falls so that the water entering the sewers will be transferred away from the road by gravity, eventually discharging to a natural watercourse.