A missing section of reinforcing rods is believed to have caused the collapse of a concrete beam that fell onto three passing vehicles on Rama II Road on July 31, killing two people and injuring two others, a fact-finding committee has concluded.
Part of the reinforcement section was believed to have been removed when the top concrete slab of the U-turn bridge was dismantled previously for in-depth repairs, Pisak Jitviriyavasin, the deputy permanent secretary of the Ministry of Transport, said on Thursday.
As a result, the outermost structure became distorted and lost support, he said, citing a preliminary report by the committee into the incident that took place in Samut Sakhon, just west of Bangkok.
The irregularities seen in the beam were unlikely to be linked to a fire caused by an accident involving a petrol tanker that occurred on the bridge on June 19, 2004, as was previously speculated, Mr Pisak added.
The Department of Highways expects to finish redesigning the bridge by the end of next month. Construction is scheduled to start in October after a public hearing, and to conclude in December, he said.
Before the bridge is officially reopened, the department and the Engineering Institute of Thailand will run tests until they are certain it meets the safest engineering standards, he said.
Mr Pisak has asked the fact-finding committee to submit a formal report to the transport minister as soon as possible, along with an action plan.
As for the compensation plan for affected parties, the Department of Highways has been instructed to speed up the payment of damages and ensure they meet ministry regulations.