EDMONTON — Dozens of terrified motorists were forced to swerve or drive into the ditch Monday to avoid a massive semi trailer barrelling down the wrong lane of a major highway on the outskirts of Edmonton.

The semi finally plunged over the guard-rail of a bridge and onto railroad tracks below, exploding into a massive fireball and killing the driver and lone occupant.

At least one witness said the driver of the large, long tractor-trailer unit appeared to be purposely trying to hit oncoming traffic.

“He was moving the steering wheel. He looked angry, he looked mad, he looked zoned out,” said William Acevedo, who had to swerve to avoid being hit.

“He hydro-planed all over the cement barrier there. We just heard a kaboom and the explosion. It was bad.”

However, others said the driver appeared to be trying to avoid hitting oncoming cars.

“At times he hit his brake — because I saw smoke come out of his rear wheel — to avoid hitting a car or something,” said Zack Novak, 45, who followed the semi for about 15 kilometres.

Carrie Balkwill of St. Albert, just north of Edmonton, was driving a van carrying her four children when she saw the cloud of dust from the semi cutting back and forth between lanes.

“What I could see from my point of view, and I’m still very shaky from it, he tried his best to avoid everybody,” she said.

“He was making himself as noticeable as possible, that’s how I saw it. When I look back at what had happened, the damage could have been more awful.”

Witness John Phillips said the truck was moving at a high speed when it struck the cement barrier.

“The truck was airborne 40, 50 feet in the air, rolled over and went right down between the two bridges there.”

Fortunately, police said no one else was hurt.

The drama started about 1:15 p.m. near Stony Plain, Alta., about 25 kilometres west of Edmonton, when RCMP received several complaints.

“The reports said he was very erratic, going from lane to lane,” said Const. Barb Roy.

As he progressed east toward Edmonton along the Yellowhead Highway, the driver crossed over and started driving against traffic in the westbound lane.

“I looked up and saw the semi truck right in front of me,” said Alex Salame. “He swerved off the road, came down into the ditch and then back up.”

Edmonton police and fire department personnel were quickly on the scene after the crash but could not save the driver.