Chunks of ice and snow fall off new Vancouver bridge's support cables, injuring two people and damaging several vehicles
Thu, 20 Dec 2012 08:14 UTC
closure of the multi-billion-dollar span after snow and ice fell from the bridge's support cables, injuring two people and damaging several vehicles.
Mike Proudfoot, the CEO of the Transportation Investment Corporation, admits the coating on the cables that was supposed to push snow away from the deck didn't work.
But, he says, Wednesday was an unusual day.
"This is an extreme weather situation," he said.
"It is very rare, especially in the Lower Mainland, but it does occur and it has had similar effects on other cable stay bridges in other jurisdictions ... Snow can accumulate on any structure over roadways and no bridge is immune to it but what we saw was a very unusual combination of winter conditions."
Proudfoot says engineers were sent to the bridge and the contractor has been asked to come up with plans to avoid such problems in the future.
The corporation says it will forgive the toll and pick up the insurance deductible for vehicles damaged on the bridge.
'It'll happen again'
Perry Adebar, a professor of structural engineering at UBC, says the bridge's construction could be to blame.
"The reason it happened, I think, is fairly clear," he said.
Christos Georgakis, a structural engineering expert from Denmark, says bridge designers often don't do risk assessments for icing, despite the fact that falling ice is common on bridges in northern regions.
"If it happened once, it'll happen again," he said. "And I think I would expect any cable-supported bridge at that latitude to have icing at some point or another."
But Georgakis adds he doesn't think it's worth redesigning the bridge.
He says no one has developed an effective way to prevent ice buildup on bridge cables, and officials should have anticipated the risk and closed the bridge.
ICBC says it has already received more than 60 claims linked to the ice falling on the Port Mann Bridge.
The $2.4-billion bridge, which serves more than 100,000 motorists every day, reopened early Wednesday evening.