Police said a truck lost control at a bend of the Rama IV bridge, knocking the pole and the transparent acrylic wall off the bridge. The accident took place at 5.30pm at the top of Phumwet Road in Nonthaburi’s Pak Kret district.

The motorist, Chalong Puangla, was not injured though the windshield of his car was shattered and the edge of the left door and front bumper were damaged.

The metal pole with a solar light panel had been put up to warn motorists of the bend in the bridge, while the acrylic sheet was erected to stop vehicles from falling off the bridge.

Chalong said he was heading to the Pak Kret pier when he heard a loud bang and thought he was hit by another vehicle. However, it was not until he was alerted by a motorcycle taxi driver that he realised his car had been hit by a pole and acrylic sheet. The motorbike taxi driver helped him remove the pole and acrylic sheet from under the car.

Natthapong Kathcapong, 41, a taxi motorcyclist from a stand nearby, said he heard a loud noise and upon looking up he saw a fully loaded truck lose control at the bend and hit the pole and wall, which then fell on the car passing underneath.

Police have removed the remainder of the wall and have launched a hunt for the truck.