The Department of Highways has apologised to the public for chronic traffic congestion caused by the expansion of traffic lanes on Rama II Road in Bangkok.
Director-general Kamol Muntham said on Friday Rama II, which is used by more than 200,000 large lorries daily, is the main throughway for traffic to the southern region.
The apology came after social media complaints about bumper-to-bumper congestion on the road went viral.
Mr Kamol said traffic congestion was the result of the department's road construction project to widen the 11.7km Bang Khunthian-Ekkachai interchange stretch by four lanes to 14.
The project is divided into three phases. The 3.5km first phase is from Bang Khunthian to Samae Dam Interchange. The 4.1km second phase covers Samae Dam-Soi Phanthai Norasaing and the 4.1km third phase runs from Soi Phanthai Norasing to Maha Chai Muang Mai.
The four additional lanes involves one lane each on the service road and main road for both inbound and outbound traffic. In addition, two U-turn bridges will also be added on the road.
Construction is expected to finish within three months, Mr Kamol said.
When completed, the expansion will be able to accommodate additional traffic, he added.