Chunks of concrete fell from a bridge onto a pickup truck, severely injuring the driver, beneath the expressway being built above Rama 2 Road, on Tuesday morning.
The accident was reported to rescuers at about 7.40am. They found a white Ford Ranger pickup stopped in a Bangkok-bound lane under the expressway structure.
Lumps of concrete had smashed through the driver's side of the windshield. The driver suffered injuries to his chin, chest and arms, rescuers said. Large chunks of concrete rested on the front seat.
The victim said there had been no warning. Parts of the beam fell down as he passed beneath the bridge. He was being treated at Vibharam Samut Sakhon Hospital.
Police were investigating.
The delayed expressway's construction has long been plagued by accidents, with parts of the structure falling on passing vehicles, injuring and even killing motorists.
Most recently, in early March, a pickup truck driver was injured by a falling crane.
