Oklahoma transportation commissioners voted to contract with an engineering firm to design a project to raise the heights of nine county bridges over I-35 to increase the clearances below.
The first nine county bridges slated for work all span I-35 in northern Oklahoma between Tonkawa and the Kansas state line. If that project proves successful, the procedure could later be replicated on dozens of other Oklahoma bridges.
The need to improve the vertical clearances of the bridges is being driven by plans to overlay the aging interstate pavement below. When an overlay is laid on a highway below a bridge, it decreases the clearance and increases the risk of the top of a tractor-trailer rig colliding with the bridge above.
Road contractors have been urging transportation officials to adopt the option of jacking up and raising the heights of the bridges, which can be done without disrupting interstate traffic and is what the department is now planning to try.
The Oklahoma Transportation Commission approved a $769,750 contract with HNTB Corp., a Kansas City, Missouri-based engineering firm, to design the initial project to raise nine Kay county bridges over I-35. The firm has experience raising bridges.
An estimated $3 million construction project to actually raise the bridges is part of the state's eight-year construction plan and is scheduled to go out to bid in federal fiscal year 2018. The work also will include repairing slope walls, fixing drainage issues and making any needed substructure repairs, transportation officials said.
The bridges will be raised by 8–18 in. with a goal of having a vertical clearance over the interstate of at least 17 ft, officials said. The national standard for new bridge construction is to have a vertical clearance of at least 16 ft. Oklahoma officials like to have the additional foot of clearance to accommodate future overlays.