A truck driver has been charged after a horrific crash on Tonkin Highway on Monday.

Moira Dunstall, a 55-year-old Armadale mother, had just driven through a green light when her Mitsubishi Magna and a semi-trailer collided at the intersection of Armadale Road in Forrestdale shortly before 1pm.

The force of the crash was strong enough to push the car 200m up the road, killing Mrs Dunstall instantly.

“It was a pretty horrible scene,” witness Chris Round said.

“It just happened so fast. I saw the actual impact.

“I saw the truck take the car and push it down the road. There was just nothing anyone could do.”

A 46-year-old Beckenham man has been charged with dangerous driving occasioning death and will appear at the Armadale Magistrate’s Court on May 14.

Mr Round said he saw car’s brake lights go on just before the truck slammed into the driver’s door, but there would have been nothing she could do.

Investigators want to hear from any other witnesses who saw the truck in the minutes before the crash.

Anyone with information or vision can call Crime Stoppers on 1800 333 000 or go to crimestopperswa.com.au.