Traffic was at a standstill for about two hours on a portion of the westbound Highway 401 after a dump truck with its box raised struck the Highway 400 overpass.
Ontario provincial police said the dump truck was travelling in the westbound express lanes when it hit the overpass around 1 p.m. on Thursday.
The raised box detached itself from the truck and the truck pulled over to the right shoulder.
Structural engineers with the Ministry of Transportation went to the scene to assess the damage to the bridge.
No injuries were reported.
The driver, a 22-year-old man from Hamilton, has been charged with careless driving as well as driving with an over height vehicle.
The westbound express lanes reopened just before 5 p.m.