Approach Roadway Drainage – Keeping Your Bridges Strong & Healthy No. 10
Roadway Drainage



Summer road maintenance will be starting soon, if it hasn’t already; and road crews will be regrading roadways to smooth and level off the road cross slope and cleaning out parallel ditches that are full of gravel deposits from the winter grind.

Proper road drainage adjacent to bridges is an important maintenance task that is sometimes overlooked and should not be forgotten. Under the approach guide rail, gravel furrows (after road grading is completed) or cinder deposits from winter maintenance create drainage dams, preventing storm runoff from exiting the approach roadway quickly.

Roadway DrainageRoadway Drainage

As seen in the photos, the deposits trap water along the shoulders, creating a pond effect, which eventually leads to deterioration of the pavement or gravel roadway. Also, when the bridge deck is lower or level with the approach roadway, storm water is directed towards and onto the bridge instead of away from it. Water on a bridge is never good, especially during the winter with freezing temperatures. Storm water runoff flowing onto a bridge can lead to numerous maintenance issues and deterioration of the structure and roadway depending on the structure type and current condition.

Municipalities should be looking at their approach roadways annually and ensuring that proper drainage exists next to the structure to help prevent costly maintenance repairs on the structure and roadway from storm water runoff.

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