Horrified motorists drove off the road to avoid a semi barrelling the wrong way on Yellowhead Trail yesterday, then watched in horror as it slammed into a median and plunged seven metres to the CN railway tracks below and erupted into a fireball, killing the driver.

Eyewitness Zack Novak, 45, followed the eastbound truck, which had been weaving back and forth between the highway's eastbound and westbound lanes, for about 15 km.

"He had many opportunities to cross the median and come back to the eastbound lane but he didn't. He stayed on that lane and at times he hit his brake - because I saw smoke come out of his rear wheel - to avoid hitting a car or something," he said.

Traffic was scattered all over the highway, some of them hit the ditch while others struck each other trying to get out of the way of the semi, Novak said.

Novak saw the truck hit the median near 184 Street.

"Immediately he went straight up in the air," Novak said. He said the unit did a belly roll before landing upside down between the bridges over the train tracks and immediately exploded.

"I drove through the fireball," he added.

But another witness said the driver 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.

Carrie Balkwill was travelling in the westbound lane and had just passed the 170 Street overpass 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," said the St. Albert mom, who was driving a van with her four children.

"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."

Nobody else was hurt in the incident, said police. Edmonton police acting Insp. Todd Laycock said several motorists called police to report the horrific sight.

Before the fatal crash, Laycock said the Mounties received reports about the semi driving erratically on Highway 44.

The truck was carrying cardboard boxes and pallets. The trucker's identity was not released last night.

Investigators are still trying to determine what caused the tragedy.

CN spokesman Kevin Franchuk said the crash caused only a minimal disturbance to rail-road operations.

**story from Edmonton Sun**