The westbound lanes of Highway 401 near Guelph have reopened after a police investigation into a fatal collision blocked westbound traffic for several hours.

A 25-year-old man died after his 1994 Ford Tempo crossed the path of a transport truck in the westbound lanes, hit the median and flipped into a ditch.

The driver was airlifted to Hamilton General Hospital, but succumbed to his injuries.

Vehicles stopped behind the collision were turned around and traffic was rerouted to Highway 6 north.

Both east and westbound lanes were restricted following the accident so an air ambulance could land.

Anyone with any information about this collision is encouraged to call the OPP Cambridge Detachment at 519-654-0150 or 1-888-310-1122.