Ontario Finds Three Factors in Nipigon Bridge Malfunction
NIPIGON, ON -- New information released by the Ontario government shows that three factors played a combined role in the malfunction of the cable-stayed Nipigon Bridge on January 10, which resulted in Canada’s only cross-country route being shut down to traffic.
While initially thought to be a cold weather failure that caused a portion of the bridge to lift, engineering reports have now found three factors that led to some 1,300 trucks a day having to detour for several weeks. First was the design of the bridge's shoe plate and its flexibility; second, a lack of rotation in the constructed bearing; and third was improperly tightened bolts attaching the girder to the shoe plate.
“When combined, these three factors produced the malfunction,” read a joint statement Thursday from the Ontario Ministry of Transportation and the Ministry of Northern Development and Mines.
Cold weather and wind were not found to have contributed to the unexpected lifting of the bridge.
Following the initial 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.
The joint statement indicated that a new permanent retrofit design has been developed to address the issues identified by the engineering reviews.
Preliminary estimates for the initial repair work and the final repair to be implemented are between $8 and $12 million.
Lastly, the Ontario government said it intends to conduct a formal route planning study and Environmental Assessment during fall 2016 for an emergency detour route. The province expects it will take approximately 18 months to complete.
You can read the investigation reports, bolt testing reports, and a number of fact sheets on the Ontario Ministry of Transportation website here.