BARRIE, ONT. -- Robert Stratton was astounded last week while driving southbound on Highway 400 into Barrie as he watched the car in front of him swerve dangerously.

"A beer can come flying off the highway, and we knew he'd been drinking," the Barrie man said.

As he called 9-1-1 to report the situation, his daughter started recording on her phone from the passenger seat.

In a panic, Stratton exclaimed to the OPP dispatcher, "There's somebody in a car that's going to kill somebody up here!"

For nearly three minutes, with his daughter documenting everything, Stratton followed the white car.

They watched nervously as it almost hit the guard rail and again as it nearly crashed into passing vehicles, all the while on the line with the dispatcher.

"There's a white car throwing beer cans out," he said to the OPP operator. "He almost hit a transport truck."

Stratton finally spotted an OPP officer on the side of the road, and frantically relayed what was going on.

The officer immediately took off down the highway in his cruiser, quickly pulling over the vehicle in question.

"He's the hero in this situation," said OPP Sgt. Kerry Schmidt. "He's the one who made that call, and could very well be responsible for saving someone's life."

The driver of the white vehicle has been identified as a 45-year-old man from the Niagara region.

"It's unbelievable, and yet it's what we see time and time again," said Schmidt.

As traffic fills the highways this weekend leading into Canada Day, police warn they would be watching for unsafe driving.

"Losing your licence is better than dying or killing somebody else and living with that the rest of your life," said Stratton.

The Niagara man has been charged with three criminal offences, including impaired and dangerous driving.