Engineers looking for information about the failure last winter of the cable-stayed Nipigon River Bridge in northwestern Ontario will have to wait a little longer.
In July, Ontario’s transportation ministry advised that a final report into the causes of the bridge failure will not be made available until the fall.
The Nipigon River Bridge, which just opened to traffic in November of last year, was forced to close temporarily in December when a portion of the roadway separated from the underlying deck during an extreme cold snap.
A portion of the bridge was reopened to traffic days later after provincial engineers completed emergency repairs.
It was determined at the time that broken bolts contributed to the separation, and the Ministry of Transportation of Ontario (MTO) sent samples to both the National Research Council (NRC) lab in Ottawa and Surface Science Western at Western University for independent testing.
Although the results of those two tests have been completed, the MTO says it needs more time to determine the exact cause(s) of the bridge failure.
On its website, the MTO says the bolt studies provided only a partial answer about the bridge failure, “and as such we think it’s premature to discuss it on its own at this time.”
The ministry also says the investigation remains a top priority and that once all the work is complete and the causes are known, it will report back to the community and make the bolt and other reports available.
Annemarie Piscopo, an MTO spokesperson, told Engineering Dimensions in July that ministry bridge engineers are continuing their analysis to determine what happened to the bridge. At the same time, an independent engineering consultant with expertise in cable-stayed bridges, Associated Engineering (Ont.) Ltd., is conducting its own analysis.
An official with the NRC said July 25 their study compared the bolts that failed on the bridge to intact bolts from the bearing assembly on the other side of the bridge. No other work related to the bridge has been performed by NRC.
PEO continues to monitor the situation in the event any engineering practice issues come forward.