Safety on streets and highways, bicycle trails, and sidewalks is essential to motorists, bicyclists, and pedestrians. Drainage systems that remove storm water run-off from streets and highways are an integral feature of a safe system. Water that remains on the roadway(1) surface can contribute to vehicle hydroplaning. In winter, standing water can freeze and cause skidding.
(1) In the context of this guide, the roadway includes the travel lanes and shoulders, if any. Streets and highways are considered roadways or roads. The travel way is that portion of the roadway for vehicle travel.
The curbs, gutters, channels, and ditches that carry the run-off away from the roadway can have a serious effect on an errant motorist or bicyclist when not designed and maintained correctly. Erosion along the roadway can also contribute to the severity of a crash or inundate crashworthy systems such as breakaway sign supports. Even headwalls, pipe ends and grates on drop inlets and pipe openings need to be safety treated when they are within the area an errant motor vehicle or bicycle can reach.
Maintaining roadway drainage is important for safety and for ensuring the long life of the roadway by:
- Preventing erosion of the roadway.
- Preventing saturation of the subbase.
- Preventing damage to roadway structures.
This guide is intended to help local road agency maintenance workers understand the importance of maintaining and upgrading drainage features on their road system to avoid an unsafe condition. Its purpose is to highlight common roadway drainage problems that can cause an unsafe condition and suggest inspection methods and corrective action. This guide is not intended to be a design guide. Readers may want to contact their State Local Technical Assistance Program (LTAP) for more details on drainage design.