No more signs of ground subsidence linked to water seepage into Purple Line tunnel
PUBLISHED : 18 Jul 2026 at 17:18
Three inbound lanes of Prachadhipok Road from Wong Wian Yai towards the Ban Khaek intersection will be reopened from 6am on Sunday after inspections found no further ground subsidence linked to water seepage into a Purple Line subway tunnel.
The Mass Rapid Transit Authority of Thailand (MRTA) said on Saturday that progress has been made in addressing the water seepage that occurred on July 8 beneath the Wong Wian Yai intersection.
The incident was linked to subsidence on Prachadhipok Road, resulting in its closure to all traffic between the Ban Khaek intersection and Wong Wian Yai.
The affected tunnel is part of the Tao Poon-Rat Burana (Kanchanaphisek Ring Road) section of the Purple Line commuter rail extension project.
Contractors have continued deep soil improvement work, or grouting, at depths of up to 37 metres to stop groundwater from entering the tunnel.
Authorities have also monitored buildings within a 30-metre radius of the site and found no significant structural movement. Engineering experts have inspected the affected area and reported no additional road subsidence, said the MRTA.
Based on the latest assessment, the MRTA will reopen all three inbound lanes of Prachadhipok Road from Wong Wian Yai towards the Ban Khaek intersection from 6am on Sunday. The road will remain open around the clock to ease traffic congestion and facilitate travel for residents.
However, outbound lanes of Prachadhipok Road heading towards Wong Wian Yai will remain closed to allow tunnel reinforcement work to continue safely.
On Saturday, Bangkok governor Chadchart Sittipunt said the situation had stabilised significantly following a series of mitigation measures, including sealing both ends of the tunnel, pumping water into the tunnel to balance pressure with surrounding groundwater, and strengthening soil around the structure.
Mr Chadchart said water seepage had been reduced substantially. Although engineers had initially planned to inject around 10,000 cubic metres of water into the tunnel, only slightly more than 1,000 cubic metres was ultimately required to achieve pressure equilibrium.
The governor added that soil reinforcement work had almost completely halted water inflow into the tunnel.
The latest inspections found no further subsidence of roads, buildings or other structures within the designated monitoring zone, indicating that the situation remains under control, said Mr Chadchart.
It has been estimated that initial repair and monitoring work could take around six months to ensure the leakage issue is fully resolved.
Workers stand at the site of a pedestrian bridge that had to be demolished on July 12 near the Wong Wian Yai intersection, where the MRTA is carrying out repairs to stop water leaking into the Purple Line tunnel. (Photo: Apichart Jinakul)