Police were on the scene of a single-car crash on Westbound Illinois 15 at Old St. Louis Road for more than an hour on Monday afternoon.
The vehicle, a black pickup truck, had rolled before coming to rest beneath the overpass.
The driver was extricated from the vehicle and taken to a St. Louis hospital, said Belleville Fire Chief Tom Pour. The man was in serious condition, Belleville police said later Monday night. His identity has not been released.
The westbound lanes of IL-15 were closed for at least an hour as police, fire and EMS workers attend to the scene. Traffic was diverted onto IL-13. The scene had been cleared by 6 p.m.