The partial brake drum would have been travelling at about 80 km/h when it struck the windshield of this SUV, killing a Calgary woman. (CBC)

A Calgary woman is dead after a piece of a brake drum shot through her windshield at 80 kilometres an hour as she was driving on the Trans-Canada Highway.

The woman, 25, was driving alone in her Toyota SUV westbound behind a tractor-trailer near the Stoney Trail exit on Monday night, said Calgary police.

Police said the partial steel drum — believed to be from a large commercial vehicle — was lying on the road and was kicked into the air as the semi drove over it.

The circular steel piece weighing about 13.6 kilograms would have hurtled back at the woman's SUV at about 80 km/h, said acting Sgt. Colin Foster from the Calgary police traffic unit.

The woman suffered head injuries and was rushed to Foothills Medical Centre, where she died. The semi driver stayed at the scene to help police with their investigation.

More than 1,000 pieces of hazardous debris have been picked up from Stoney Trail alone in the last six months. (CBC)

Police are looking for the driver of the commercial vehicle from which the drum fell.

"What we are seeking is for any commercial vehicle driver to examine his vehicle and come forward so we can complete a thorough and full investigation on behalf of the deceased's family," said Foster.

"I can't comment as to whether any charges are pending on that case. The driver … may not know that this defect has occurred on this vehicle."

Foster said this type of event is "exceptionally rare," but encouraged drivers to keep a safe space between their vehicle and the one in front.

"So that if something does happen they may have a chance they can avoid it," he explained.

Call 911 to report dangerous debris

Records for Carmacks, the company in charge of patrolling Stoney Trail for debris, show a crew went through the area about an hour before the accident, said Gary Brooks, a highway division manager.

"We do routine patrols in the weekdays every two hours between 6 a.m. and 6 p.m. and every four hours after that," he told CBC News.

In the last six months, Carmacks has picked up more than 1,000 pieces of hazardous debris from Stoney Trail alone, Brooks added.

Foster encouraged the public to call 911 if they notice any debris or dangerous items lying on the road.

"Those are sort of hazards of the road that everybody has got to be aware of, and the sooner we know that there is debris out there, the sooner we can get that stuff addressed and removed," said Jack Brown, an operations manager with Volker Stevin, the company that maintains highways in southern Alberta.

With files from the CBC's Tara Fedun