EXPLAINER

How and when do officials decide to close B.C. highways?

What goes into the decision and who makes the final call? What drivers should know.

Closures 'not taken lightly,' ministry says

Bad weather also caused the closure of Highway 3 Thursday in both directions in several parts of the Kootenays, including the Kootenay Pass. (Bob Keating/CBC)

On Thursday night, every major highway linking B.C.'s Lower Mainland to the rest of the province was shut down due to treacherous winter conditions.

The Coquihalla was first closed around noon PT. It reopened at 4 p.m., only to be closed again two hours later.

It would remain closed until 2 p.m. PT on Friday. Hundreds of cars were stuck on the roadway overnight

The Coquihalla was "like a sheet of ice," according to stranded drivers. (DriveBC)

Mike Lorimer, the Ministry of Highways regional director for the southern Interior, said the decision to reopen was made because the weather forecast only called for some seasonal snow and a drizzle — not treacherous freezing rain.

On Friday, he explained how the choice to close roadways is made. 

What makes a highway unpassable?

Lorimer said "it's very rare" for a highway to be closed "proactively," or before an accident has happened — he said most closures happen after the fact.

However, he said there are circumstances that lead to pre-emptive shutdowns.

The Coquihalla was also closed in December, after heavy snow made the road too treacherous to drive on. (Ministry of Transportation)

"We have to have a situation that either our [snow]plows can't keep up with, or there's a hazard that just can't be dealt with through normal adjustments of driving behaviour [such as slowing down]," Lorimer said.

"Obviously, in the case where something specific closes the highway — like a vehicle incident or a slide — that's an easy decision. When you're making that proactive decision ... there's a lot of thought that goes into it."

Who makes the decisions?

Lorimer said the choice to close a road ultimately lies with the ministry's district managers.

In B.C., there are 11 such managers — each of whom is responsible for a specific section of highways.

The Coquihalla roadway was closed most of the day Thursday and into Friday afternoon. (Gian-Paolo Mendoza/CBC)

They make decisions based on the forecast and reports from staff in the field, Lorimer said.

"[Managers are] out there watching the storm, watching maintenance contractor performance, watching webcams ... you basically look at all the information available and go from there," he said.

Informing drivers on the road

Once the decision to close has been made, Lorimer alerts and social media posts are pushed out. The ministry's website is also updated.

The problem is, Lorimer noted, is reaching drivers who don't have passengers to check conditions online on their behalf.

The Ministry of Transportation said it's working to improve its signage on major B.C. highways to warn drivers sooner about road closures. (Gian-Paolo Mendoza/CBC)

"We don't want to encourage distracted driving," he said.

Lorimer said the ministry is working on improving roadside neon signs. The goal is to have boards set up strategically so drivers will see them before they drive too far into a blocked area.

"We want to give people the chance to turn back," he said.

When are highways reopened?

As for reopening, Lorimer said that "really depends" on the reason for the initial closure.

"Basically, the only rule to reopening is whether or not it's safe," he said. "There is no hard-and-fast rule."

Once highways are deemed safe, Lorimer said the ministry calls for a staggered opening. First, cars that have been waiting — like the ones who sat overnight on the Coquihalla — will be allowed forward. Then comes local traffic, followed by the broader public.

Workers chat with a driver near Hope, B.C., early Friday morning as they wait for the Coquihalla highway to reopen. (Gian-Paolo Mendoza/CBC)

Ironically, the manager said the rush of new traffic can often cause more problems.

"It's human nature: you've been stuck and delayed and you want to be somewhere," Lorimer said. "So, we sometimes see speeding or aggressive driving that can lead to further incidents."

After the Coquihalla reopened Friday, a speed limit of 80 km/h was in place to prevent such accidents.

With files from CBC's Farrah Merali