A day after a massive fuel truck fire on the Metropolitan killed one person, the investigation into what caused the blaze has begun.

““There was a vehicle - a heavy vehicle - that had stopped in the middle lane. We don't know why this vehicle had stopped yet, however it did cause a sudden stop in traffic where two other heavy vehicles that were following, a cube van and a platform vehicle that was transporting cement, ran into each other and behind them they had a 45-foot tractor trailer that was transporting fuel,” said Surete du Quebec spokesperson Lt. Jason Allard.

Gilbert Prince, 52, was trapped inside the cab of his truck and died in the fire.

It is unclear how long the westbound lanes of one of Montreal’s major traffic arteries will be shut down, but Transport Minister Jacques Daoust said in the best-case scenario it could reopen within days, but that is unlikely.

In a news conference Wednesday afternoon, Daoust explained that investigators are taking core samples of the concrete in front of, behind and directly below where the explosion occurred, and that preliminary results from in front of and behind the truck are very good. He said the span wasn’t weakened in any way in those spots.

“First, we were concerned with the expansion joints, and they seem to be okay, so that’s good news. The coring that is being conducted now on the two extremes… so far coring looks good.”

He said investigators still need to inspect under where the truck caught fire, and will take a total of 12 core samples of the concrete.

The samples will be tested in a Montreal lab and are due back within 12 hours. By Thursday morning, officials will know how stable the structure is.

“I don’t want to say I’m optimistic, but it seems it was very localized,” said Daoust, who said he expects some concrete reconstruction will be necessary, but so far it is unclear what work will need to be done.

Coderre added that it’s a “step-by-step approach” and “we don’t want to speculate.”

“Tomorrow morning, don’t expect that it’s open,” he said. “One day at a time.”

Transport Quebec spokesperson Sarah Bensadoun said no inspection can be carried out until the SQ has concluded its investigation and there is no timeline for the reopening of the westbound lanes.

“On the east side, the structure is not compromised and that made it possible for us to reopen for traffic,” she said. “For the western portion, we are not able to give any type of information since we don’t have a diagnosis yet.”

Allard described a scene in which the truck had not only been burned into the road but had melted the asphalt itself. He said Montrealers should expect a lengthy cleanup and repair in the affected area. The asphalt will need to be repaved.

Surete du Quebec and Montreal police are continuing to work together to divert traffic in the area. Highway 40 East and Cremazie Blvd. have both been reopened.

"We've just reopened the service lanes of the 40 in both eastbound and westbound and at the moment the Highway 40 westbound remains closed but it's open eastbound," said SPVM spokesperson Andre Durocher. 

Police have been stationed at every intersection between Christophe Colombe and St. Laurent to ensure traffic moves as fluidly as possible. Durocher said drivers should avoid Cremazie by taking Sauve or Jarry.

"When you close three lanes on a major artery like the Metropolitan, there obviously will be an impact," said Durocher. 

While construction of the Metropolitan began in the late 1950s, Bensadoun said the age of the highway did not factor into the decision to shut down the westbound lanes.

“Before the accident, the structure was perfectly fine,” she said. “We have inspections. We do that two or three times a year. We also have patrol units, they go every day on the structure and will report if there’s anything that needs to be corrected.”