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Safety upgrades planned for North Shore bridges

Risk of collapse too high for new standards

The province is set to spend millions of dollars upgrading the two North Shore bridges so they won’t be at risk of collapse in the event of a nautical disaster.

The Ministry of Transportation and Infrastructure is now seeking bids for projects on the Lions Gate Bridge and Ironworkers Memorial Second Narrows Crossing that would mitigate risk of serious damage if a ship were to drift off course in either narrows.

The province commissioned a risk study of both bridges in 2015 that found the annual risk of collapse was less than one in 1,000 which is considered acceptable for “regular” bridges. But the Lions Gate and Ironworkers are considered critical to the transportation network and current federal bridge design regulations require a much lower risk threshold of less than one in 10,000.

“They were built to the standards of the day before this sort of criteria was developed. Nevertheless, now that we know about it, it was deemed appropriate to move forward to strengthen both structures to exceed that criteria,” said Ed Miska, executive director of engineering services for the ministry.

On the Lions Gate, crews will be building up a rock fill berm around the base of the south tower, similar to the one already protecting the north tower. The berm would act as a buffer or bumper protecting the Lions Gate from a ship’s bow or hull.

On the Ironworkers, the ministry will be installing a new steel barrier to protect the bridge’s trusses as well as in-water structures called dolphins designed to redirect a ship drifting off course back into the centre of the channel.

There have been a number of cases of vessels hitting the bridges over the years but the rules that govern how ships move in and out of the harbour have been strengthened significantly over the years, handing control of ships in the harbour to the Pacific Pilotage Authority and using tugs to guide ships through the narrows, Miska said.

“The likelihood of a ship going off course is extremely, extremely low because of the operational procedures that have been put in place by the Vancouver Fraser Port Authority,” he said.

“Notional” budgets for the two projects range from $15 million for the rock fill berm to as high as $55 million for the dolphins, depending on which preferred designs come from the bidding process.

For anyone fantasizing about a replacement for either the Lions Gate or Ironworkers, which were completed in 1938 and 1960, offering more lanes of traffic on and off the North Shore, don’t hold your breath Miska said

“They will still be in place for quite some time. We wouldn’t be going forward with these sorts of improvements if the bridge was going to be replaced. They both still have quite a bit of life left in them,” he said.

And no, the projects aren’t related to the Trans Mountain pipeline project or the expected 10 per cent increase in shipping traffic it will bring to the harbour, Miska added.

“This is something that we need to do and is not related to the Kinder Morgan project,” he said.