Port Mann Bridge closure being reviewed
Posted: Dec 20, 2012 6:14 AM PT
Last Updated: Dec 20, 2012 8:55 AM PT
The head of the Crown corporation that built the Port Mann Bridge says the company is reviewing yesterday’s 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’s 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 dispatched to the bridge and the contractor has been asked to come up with plans to avoid such problems in the future.
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.
“The cables on that bridge are inclined over the bridge deck. If you look at the other bridges in the Lower Mainland, they’re not like that.”
‘It’ll happen again’
Christos Georgakis, a structural engineering expert from Denmark, says dangerous situations like the falling ice chunks on should be expected.
Georgakis says bridge designers don’t often do risk assessment 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 in the early evening.
I haven’t been over the new bridge, (and will avoid it as much as possible). After reading this article, I do recall the design had cables which do hang over the traffic lanes.
I was out shovelling the snow yesterday, quit exhausting, given it was wet ( aka heavy ) snow. I did it in 3 stages. During the last stage, the snow was melting and I was getting bombarded by snow chunks falling from trees and power lines etc. It was actually about 2 inches thick on some power – line spots.
Hence, the scenario described above doesn’t surprise me, it makes sense.
However, they seem to dismiss being pro-active to prevent any re-ocurrence. We are talking about snow freezing into chunks and dropping from high distances. That is extremely dangerous if not potentially lethal.
Can one imagine driving on a congested bridge and all of a sudden a loud crash after something hit your car….the noise and the feeling of impact ? Then one has to wonder if one can maintain control of the vehicle, or if other vehicles experience this and swerve out of control.
ICBC had 60 claims….?
Given the deductible, 60 drivers are out at least $300 each after paying the toll….and ICBC (aka US)covers the rest.
We haven’t even hit the historical snow season yet…..