Water has leaked into the Purple Line subway tunnel under construction beneath the Wong Wian Yai intersection in Thon Buri district of Bangkok.
The incident has been linked to subsidence on Prachadhipok Road above the tunnel, resulting in the closure of the road to all traffic between the Ban Khaek intersection and Wong Wian Yai at 5.30pm for repair work.
Visiting the site earlier, Deputy Transport Minister Siripong Angkasakulkiat said the surface of Prachadhipok Road had subsided by 20 centimetres on Thursday morning and engineers would have to take urgent action to ensure safety and prevent further damage.
The Metropolitan Rapid Transit Authority (MRTA) said the leak into the tunnel 30 metres underground happened on Wednesday at the joint of a sump pit, which is a part of the Tao Poon-Rat Burana section of the Purple Line extension project.
Mr Siripong said some new cracks had been reported at some local buildings and officials were checking structures in the area. Engineers would consider if evacuation would be necessary.
The civil works for the Purple Line extension have been split into six different contracts, with the MRTA awarding them to five major Thai construction companies.
Italian-Thai Development Plc and Nawarat Patanakarn Plc formed a joint venture to build the 3.1-kilometre underground section passing beneath the Chao Phraya River.
A video from the MRTA showed a Purple Line tunnel partly flooded, with neck-deep water levels in some sections.
Prime Minister Anutin Charnvirakul visited the scene at 11pm on Wednesday and said the water leakage was under control, so the situation was different from the huge sinkhole incident on Sam Sen Road in Dusit district last year.
