City Hall has ordered the suspension of work on an overpass at Bang Kapi intersection after a 10-metre-long sheet of metal crashed to the ground as it was being lifted by a crane, killing one worker and injuring two others.
Rescue workers were notified about the accident at 1.50am on Thursday.
Workers were removing the metal sheets which support the overpass deck when the accident happened.
Several workers were tying wire cables to the edges of the metal sheet so it could be lifted off the overpass by a crane when the unsecured ends suddenly crashed onto Seri Thai Road.
Police said investigators have summoned the construction site engineer for questioning. The engineer said he had no idea what caused the accident, as he wasn't at the site when it happened, police said.
The BMA has temporarily suspended work on the site until safety can be assured. The BMA has also launched a probe into the accident, he said.
After the incident the former president of the Thailand Council of Engineers, reposted a video of the overpass he had posted in April.
"I said in April that the flyover construction did not meet safety standards. Now someone has died because of it. This is a major issue in Thai society," he wrote.