Metro Vancouver snow: Watch how crews prevent 'ice bombs' from falling on local bridges

With Metro Vancouver seeing its first snowfall at the city level, the province is preparing to clear buildup on local bridge cables to prevent so-called "ice bombs" from falling.

B.C.'s Transportation Ministry said in an update Friday that contractors are ready to use cable collars to clear snow and ice from the Alex Fraser and Port Mann bridges as needed.

The collars were installed after an "ice bomb" fiasco in 2012, which damaged about 350 vehicles on the Port Mann when built up snow and ice fell from the collars, shattering windshields. Similar incidents have been reported on the Alex Fraser Bridge in recent years, even though the provincial ministry says "falling ice and snow (was) a rare occurrence for the first 30 years of its operation."

The cable collar system was installed in 2018 and includes 10 collars, but they require manual operation by rope-access technicians to clear the cables. The Port Mann Bridge also now has snow-clearing collars on each of its 288 cables.

The ministry says the collars "are basically chains that fit around the bridge cables." As they move down the length of the cable, they remove ice and snow. It takes less than a minute for the collar to travel to the bottom of a cable.

Technicians then manually detach the collars from the cables, move them back to the bridge tower and "hoist them back up to the top of the cables," the ministry says. Outside lanes on the bridge are temporarily closed while the clearing happens.

"In the years that cable collars have been used, they have been successful in removing most of the snow on the cables. However, some snow may be shed naturally from the cables as the weather warms or if it is blown off," the Transportation Ministry said in a statement.

"To better prepare for the weather conditions that lead to falling ice and snow, the ministry has taken steps to improve its weather forecasting and will be activating the cable-collar systems sooner in a weather event."

Before those were installed, the Transportation Ministry used other creative approaches to clear the cables, including a chopper that was flown overhead to blow away snow and ice on at least one occasion in 2016. 

Dozens of insurance claims have been filed because of damage from the ice bombs.