Quebec's provincial police say it will take some time to complete their investigation into the death of a driver whose car flew off an overpass on a highway west of Montreal.

The vehicle left Highway 30 in Vaudreuil-Dorion and cleared the overpass before flipping over and landing on its roof on Harwood Boulevard Thursday around 10 a.m.

Authorities are looking at the possibility that snow acted as a ramp and guided the vehicle off the road.

The Montreal area was blanketed by more than 50 centimetres of snow over the past two weeks, and city crews have been working to remove it for more than seven days.

"Our investigators are still piecing together the physical proof from the scene," said provincial police Sgt. Daniel Thibaudeau. "We know that she drifted slightly off to the side of the roadway before flipping over."

"Thankfully, there were no cars that were passing on Harwood at that time, so there were no other collisions that occurred. But, as the pictures show, it wasn't a very forgiving collision. She had no chance," he said.

The Sûreté du Québec said it could take several weeks to complete an investigation.

The SQ said its investigation will look at the vehicle's mechanical condition, the driver's health, the state of the highway and whether the driver could have been distracted.

A spokeswoman for Transport Quebec, Sarah Bensadoun, said the consortium that controls Highway 30 has to abide by the same snow removal criteria as Transport Quebec does.

Bensadoun said all lanes have to be cleared within 48 hours of a snow storm. If more than 25 centimetres fall, the crews have an extra 24 hours to remove it.

"The security issue for the guard rails is that they have to stop accidents. That's why they have to be cleared as quickly as possible," said Bensadoun.

The private consortium that operates Highway 30 and Transport Quebec are refusing to discuss the driver's death or the condition of the overpass pending the outcome of the investigation.

In a similar case in 2005 , a 48-year-old man died after driving off an overpass on Chemin Côte Vertu in Montreal. The coroner's report states the driver might have missed the curve in the road, but accumulated snow created "a launching ramp," which landed the car on Highway 40 below.

A coroner who investigated a similar case in 2005 said packed snow could have acted as a ramp. (CBC)