A 23-year-old woman is in hospital with life-threatening injuries after being ejected from her vehicle during a single-vehicle crash on Highway 427 during the morning commute.

The accident, which occurred at about 5:30 a.m. near Derry Road, snarled traffic in the area for about three hours.

Ontario Provincial Police say the Hamilton woman lost control of her silver Acura, crossed three lanes of traffic and hit the grassy median.

The impact caused the car to flip end-over-end eight or nine times, and ejected the woman, police said.

Alcohol may be a contributing factor in the crash, Const. Dave Woodford told reporters.

"That's possibly the reason why she lost control of her vehicle and left the roadway," he said at the scene.

Woodford also said the driver wasn't wearing a seatbelt, which is why she was thrown from the vehicle.

The driver is in Sunnybrook Health Sciences Centre. Her name has not yet been released.

RIDE statistics

Meanwhile, the OPP said they pulled almost 1,200 impaired drivers off the roads during its five-week holiday RIDE program.

Drunk-driving charges were laid against 336 motorists, while another 856 drivers received 12-hour driving suspensions. Officers charged 13 drivers on New Year's Eve alone.

Police said three people died in collisions directly related to alcohol during this year's campaign, compared to one alcohol-related fatal crash last year.

"Impaired driving continues to be the leading criminal cause of death in Canada," OPP Commissioner Julian Fantino said in a statement on Thursday.

"I am disappointed that a small number of people continue to drink and drive. A small number of people still believe they are immune to the law."

Fantino said 449 people were killed on highways in 2007. Alcohol was behind 80 of those accidents, a figure Fantino called "totally unacceptable."

The OPP checked 846,440 vehicles during its festive RIDE initiative. Another 3,200 charges were laid under the Highway Traffic Act.

In Toronto, police laid 69 impaired charges and 197 suspensions during the holidays. Check out the force's statistics here.