Authorities have intensified repair and stabilization efforts at the Southern Purple Line MRT project tunnel site in Bangkok’s Khlong San district following reports of water leakage and road surface settlement. Governor Chadchart Sittipunt visited the affected area near Wong Wian Yai station on Saturday to oversee the ongoing work aimed at reinforcing the ground and preventing further issues.
Urgent Stabilization Measures Underway
The incident came to light on Wednesday night after heavy rainfall led to water seepage inside the tunnel, which is under construction for the Tao Poon-Rat Burana section of the MRT. In response, city officials promptly evacuated residents from nearby buildings and closed off the adjacent road to ensure public safety. Governor Chadchart, recently beginning his second term, also ordered the removal of a pedestrian bridge situated over the construction site due to detected subsidence at its midpoint. This action is intended to clear the way for the deployment of specialized equipment.
Four grouting machines have been brought in to inject cement-based materials deep into the soil. This process aims to strengthen the ground, mitigate further water ingress, and stabilize the surrounding environment. Workers are currently drilling to a depth of 37 meters, extending below the tunnel’s base level of 31 meters, as part of these reinforcement efforts.
Continuous Monitoring and Safety Protocols
Civil engineering expert Thanes Weerasiri, who is advising on the situation, confirmed that monitoring equipment installed in collaboration with Kasetsart University shows no significant movement in nearby buildings. Advanced instruments, including tiltmeters and inclinometers, are in use to detect any structural leaning and measure ground displacement horizontally and vertically. The data collected from these sensitive devices is transmitted wirelessly to the Bangkok Metropolitan Administration (BMA) control center, enabling officials to maintain constant surveillance.
Despite overnight rainfall, Mr. Weerasiri noted that groundwater levels remained stable, indicating that the situation had not worsened. He also differentiated the current incident from a previous sinkhole event at Vajira Hospital, explaining that the Purple Line seepage appears to originate from below ground, rather than through an opening at the surface.
However, minor cracks have been observed on the road surface, necessitating continued vigilance and heightened caution from authorities. The BMA has established a complaint center in the vicinity to provide assistance and information to affected residents regarding the ongoing monitoring and safety measures.
Impact on Residents and Traffic Advisories
The water seepage has impacted 141 residents across two apartment buildings. While 52 residents were temporarily evacuated, 34 chose to remain in their homes. Some residents have reportedly left the area entirely. Governor Chadchart assured that the BMA is committed to supporting those affected.
Traffic disruptions are in effect, with Prajadhipok Road closed from the King Taksin the Great Monument to the Yaek Baan Kaek intersection. Motorists are advised to use Issaraphap Road, Lat Ya Road, and Somdet Chao Phraya Road as alternative routes while repair work progresses.
Background on the Purple Line Extension Project
The Southern Purple Line MRT project, extending from Tao Poon to Rat Burana, involves complex civil works divided into six contracts. These contracts have been awarded to five major Thai construction firms by the Mass Rapid Transit Authority of Thailand (MRTA). The specific 3.1-kilometer underground section passing beneath the Chao Phraya River is being undertaken by a joint venture between Italian-Thai Development Plc and Nawarat Patanakarn Plc.
