Highway Patrol officers are appealing for public assistance following a crash in Sunbury on Thursday, October 19.
Investigators believe a man driving a Toyota Hilux utility was travelling through roadworks along Lancefield Road when he crashed into the back of a stationary truck, about 12.30pm on October 19.
It is believed the impact of the collision forced the truck to roll, and subsequently hit another vehicle.
The driver of the utility, a 27-year-old Essendon man, sustained life-threatening injuries and was airlifted to hospital.
No one else was injured, and the exact cause of the collision is yet to be determined.
Investigators want to speak to anyone who witnessed the collision, or who may have footage of the Toyota Hilux driving along Lancefield Road before the collision occurred.
Crime Stoppers: 1800 333 000 or www.crimestoppersvic.com.au.