Roadway Drainage Design

This online engineering PDH course provides a detailed description on the drainage design roadways.

 

Provision of sufficient drainage is an important factor in the location and geometric design of highways. Drainage facilities on any highway or street should adequately provide for the flow of water away from the surface of the pavement to properly designed channels. Inadequate drainage will eventually result in serious damage to the highway structure. In addition, traffic may be slowed by accumulated water on the pavement, and accidents may occur as a result of hydroplaning and loss of visibility from splash and spray.

 

Generally, when providing the drainage design for roadways, surface water and subsurface water must be taken into considerations. Surface runoff is the flow of water occurring on the ground surface when excess rainwater, stormwater, meltwater, or other sources, can no longer sufficiently rapidly infiltrate in the soil. This can occur when the soil is saturated by water to its full capacity, and the rain arrives more quickly than the soil can absorb it. After water infiltrates the soil on an up-slope portion of a hill, the water may flow laterally through the soil, and exfiltrate closer to a channel. This is called subsurface return flow or throughflow.  Surface water is divided in two parts: on-site water and off-site water, where the former is the water that is directly generated from the road and the latter is the water that is generated from outside the roadway limits, but has to be accounted for, by either bridge structures or box culverts; on-site water is generally handled by ditches for rural roadways and a system of inlets and pipes for urban roadways.

 

This 3 PDH online course applicable to civil and transportation engineers who are interested in learning about the principles to be considered when selecting and designing the road drainage system.