One driver is dead after an accident on Calgary's Deerfoot Trail Wednesday morning involving a semi-truck hauling a crane and a push-truck that was travelling behind it.

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The driver of a push-truck, which was helping a semi-truck transport a crane, was killed instantly on Deerfoot Trail on Wednesday after his truck slid under the trailer of the semi it was attached when the crane fell onto the road. (Kyle Bakx/CBC)

All northbound lanes on Deerfoot Trail at the 17th Avenue S.E. overpass have reopened after heavy-duty cranes were called in to move the crash wreckage.

Crews also had to clean up a large fuel leak at the scene.

Investigators believe the semi-truck became unstable when it attempted to make a turn near the overpass at about 5:30 a.m. MT, causing the 150,000-kilogram crane to shift and fall to the side of the trailer.

"At that point, there was a push-truck that was connected to the rear trailer. That push-truck was then sucked under the back of the trailer that was hauling the crane," said acting Sgt. Bob Pughe.

Calgary father killed in crash

The 39-year-old driver of the push-truck was killed instantly. The Calgary man was married and had two young children, police said.

The man's wife has been notified, but did not want his name released.

He was a driver for Whissell Contracting of Calgary, which was hauling the crane to Jasper for PCL Construction.

"Our thoughts and prayers are with the driver’s family and their tragic loss," said the company in a statement. "Currently we are dealing with grief counsellors for his family and our staff. We respectfully request that you allow us some privacy to deal with this tragedy."

Police say weather, speed and alcohol were not factors in the crash.

Investigators will be looking at how the chains securing the crane came loose.

"This [investigation] will take more time than a regular motor vehicle collision just because of the size of the vehicles. At this time, we have a mechanic on scene who is inspecting the vehicles, but there will be further mechanical inspections in the days to come," said Pughe.

Alberta Transportation says a safety review conducted in 2009 resulted in improvements at the site. New warning signs were posted and reflective signs were put up on barriers near the crash site.

Nancy Beasley Hosker of Alberta Transportation says motorists are advised to go slower than the posted speed on that curve for safety reasons depending on driving conditions.