Working with ODOT, Triad Design engaged its full range of transportation engineering services for this three-phased virgin alignment roadway and bridge project to redirect US-70 traffic around The City of Durant in Bryan County, Oklahoma. The major east-west corridor which links North Carolina’s east coast to Arizona, US-70 passes through a fully developed downtown Durant, making a bypass the only feasible solution for traffic mitigation. The 4-lane divided roadway is a controlled access facility with a design speed of 65 mph comprised of a full cloverleaf interchange, a folded-diamond interchange, and a common diamond interchange. 

Notable for its structural challenges, the project’s twenty-two bridges, all designed to AASHTO LRFD specifications, include two mainline bridges over the Kiamichi RR, four over two creeks, and numerous bridges contained within the four overpasses. Structural components employed for the pre-cast concrete and steel bridges were equal and unequal spans, horizontal curves, curved deck, chorded beams and skewed elements. A “flyover bridge” project was added south of the US-70 Bypass to provide improved access to Durant’s Choctaw Casino.