Temporary shoring has been installed to allow the highway to reopen but the five-year-old Sabo Bridge itself will remain closed until repair work is completed.
The bridge, which carries bicycle and pedestrian traffic over Hiawatha Avenue in Minneapolis in Minnesota, was closed a week ago after the cable connection broke on the bridge’s pylon, causing a pair of cables to break loose. The bridge design includes 18 cables on each side of the bridge, for a total of 36 cables.
Emergency work has been carried out to build supports beneath the damaged section. City crews installed four sets of supports to shore the structure so that the tension could be released from a second set of cables that were also compromised. This enabled checks on the tension in the rest of the cables and in the cable connections at the pylon. Inspectors have also been measuring the loads on the shoring structures, deflections of the bridge deck and looking for any new visible signs of cracking, bowing, or frayed strands of bridge cable.
The Sabo Bridge, which has a 60m main span and a 30m-tall pylon, opened in November 2007. The overall structure is 671m long.
City engineers have consulted with the Sabo Bridge’s original designers and others to inspect, stabilise and repair the bridge. The city of Minneapolis and Hennepin County have appointed forensic engineering firm Wiss, Janney, Elstner, Associates to assist in determining the cause of the failure in order to develop plans to move forward.
Since its opening, the Sabo Bridge has undergone inspections every year with the most recent inspection taking place in September 2011. Those inspections did not find any problems with the bridge’s cable support system.
