The cables that hold up the new Port Mann Bridge will be outfitted with devices to clear snow buildup and prevent a repeat of the falling ‘ice bombs’ incident that terrorized motorists late last year.
The custom snow sweepers are two feet long and consist of a set of wheels, scrapers and brushes and will be raised and lowered along the cables during wintry weather to remove any ice and snow buildup.
They’re being installed on 152 of the 288 bridge cables that cross the roadway starting this week.
Transportation Minister Mary Polak said they’ll initially be positioned at the bottom of the cables and be manually winched up to the top and dropped back down to clear snow when required.
“It clears off all the snow in a gradual manner, which was intended in the first place,” she said.
Later, they’ll be positioned at the top of cables and then dropped down and back up by remote control when needed.
“The initial solution may not be that elegant,” Polak said. “But we wanted to make sure we have a solution for the public.”
More than 250 vehicles were reported damaged Dec. 19 by ice that fell from the bridge’s cables, which cross overtop of traffic lanes unlike the ones on other local suspension bridges.
Polak said the sweepers are just one of the preventative solutions engineers are testing to ensure bridge users are safe from falling snow and ice.
Four hydrophobic silicon-based coatings are being tested to determine which performs best.
The intent is to coat all the cables this summer and make snow or ice more likely to slide off.
A de-icing solution has also been found that can be sprayed on the bridge cables, although Polak referred to it as more of a “last resort” as it likely means a planned closure of some lanes.
The cable sweepers are being tested at Cypress Bowl and engineers say they should glide smoothly along each cable without damaging the cable sheath.
They’re to be used as soon as snow starts to fall and ongoing inspections will gauge how soon cables must be brushed again.
Polak was unable to provide a cost estimate, but maintained the bridge contractor will pay the entire bill, not taxpayers.
Polak praised contractor Kiewit/Flatiron for their “astonishing effort” in working to quickly find a fix.
“They have put their top people on this – it’s been all hands on deck.”
The so-called ice bombs incident was a major black eye for the new toll bridge, centrepiece of the new $3.3-billion Port Mann Highway 1 project, just weeks after it officially opened.
Inadequate de-icing of the bridge deck was also blamed for a subsequent 40-vehicle crash Jan. 3.
“Over the last month, we’ve installed additional weather stations to help identify threatening weather conditions well in advance,” said Kiewit Infrastructure Group president Scott Cassels.
“We must finish-real world testing, but we believe the cable sweepers, coatings and de-icing sprays will be effective enhancements to the bridge.”