State departments of transportation (DOTs) are facing increasing challenges of maintaining regulatory compliance with stormwater discharge requirements under the Clean Water Act. Finding available land to treat stormwater within the highway right-of-way is challenging, and the clear zone is often an ideal location. The clear zone is close to the source of the runoff and provides space for open, vegetated stormwater treatment measures that are effective and easy to maintain. Retrofitting roadway swales to include impermeable check dams to retain stormwater and promote infiltration is a cost-effective stormwater treatment approach for state DOTs. However, the AASHTO Roadside Design Guide does not provide specific guidance on check dams in the clear zone. Preliminary analysis has been completed on the trajectory of errant vehicles on rock check dams; however, simulation of various configurations, including check dam material, has not been completed.

This research would protect the traveling public while reducing treatment structure costs and right-of-way takes by creating guidelines for design of stormwater treatment check dams in the roadside clear zone. Check dams allow for the increased retention and filtration of roadway runoff within existing or minimally expanded right-of-way. This research will provide necessary crash test simulation modeling to inform guidance for traversable roadside check dams.