US 50 Blue Mesa Emergency Repair Services
Safety concerns following high profile bridge closures across the country prompted FHWA to issue a memo in December of 2021 requiring all states to perform non-destructive testing of Fracture Critical Members fabricated from the high strength AASHTO M244 Grade 100 Steel (T1 Steel). Colorado had two T1 steel bridges covered by the memo, K-07-A (Lake Fork Bridge) and K-07-B (Blue Mesa Middle Bridge), which are both long-span steel structures carrying two lanes of US-50 traffic over the Blue Mesa Reservoir.
Each structure has three fracture critical spans consisting of two continuous welded steel plate girders. These bridges provide critical access for hospital patient transfers between Montrose and Gunnison, commercial traffic throughout Colorado’s western slope, and recreational access to the Curecanti National Recreation area and Black Canyon of the Gunnison National Park.
During inspection on April 18, 2024, inspectors identified a 2.5-inch crack along with a weld defect indication on one of the bridges and determined the presence of internal defects within the weld. After uncovering the weld defects and the cracking, the CDOT Executive Management Team (EMT) and the State Bridge Engineer recommended the indefinite full closure of the structure.
In response, CDOT quickly contracted Michael Baker International, Kiewit Infrastructure Company, Benesch, and BDI within two days of the closure. The purpose of this emergency project was to restore a safe transportation connection for communities on either side of the K-07-B bridge with a goal of reopening the bridge to the public by the July 4th weekend. The project included emergency bridge repairs, county road improvements to restore local detour routes for residents, maintenance of traffic plans for the permanent repair phase, and structural analysis of bridge capacity during construction and inspection loads for both the critical repairs and permanent repair phases. It also included inspection and permanent repairs for K-07-A bridge.
Emergency repairs on K-07-B were completed by July 4, meeting CDOT’s goal and the public’s expectations. After 20,000 design hours, installation of 410 tons of steel plate and more than 50,000 bolts, permanent repairs are completed on both bridges and they were reopened for full use by the public by Thanksgiving 2024.