Steven Del Duca, Minister of Transportation, and Michael Gravelle, Minister of Northern Development and Mines issued a statement updating the investigation of why the Nipigon River Bridge failed and report how repair work is progressing.
In January the Nipigon River Bridge was unexpectedly closed to traffic due to an issue with the tie-down connection on the northwest corner of the bridge. Following the closure, two firms were contracted to test the bolts from the bridge. The testing confirmed that the bolts broke due to overloading and not due to any flaw in the bolts themselves.
A thorough engineering analysis has found that three main factors led to the malfunction: first was the design of the shoe plate and its flexibility; second was a lack of rotation in the bearing that was constructed; and third was improperly tightened bolts attaching the girder to the shoe plate. When combined, these three factors produced the malfunction. Neither cold temperatures nor wind contributed to the closure.
A new permanent retrofit design has been developed to address the issues identified by the engineering reviews, says MTO.
“This permanent retrofit will ensure that the Nipigon River Bridge functions safely for road users throughout its intended useful life. This design will be reviewed by Associated Engineering (Ont.) and ministry bridge engineers and will also be applied to the south portion of the bridge, where construction is progressing well.”
This fall, the province says it will also move forward with a formal route planning study and Environmental Assessment for an emergency detour route. This is expected to take approximately 18 months.
“While our government has full confidence that the retrofit, once complete, will ensure that the bridge is safe for all users, this detour route would provide an alternate option for local residents and businesses in an emergency.”