BANGKOK — 9 July 2026, Authorities have closed all traffic lanes between Ban Khaek Intersection and Wongwian Yai after water leaked into a construction shaft of the southern Purple Line MRT project, as engineers work to pump out water and repair the damaged section.
The closure follows an incident in which groundwater seeped into a sump pit beneath the underground railway construction site at Wongwian Yai. On the night of 8 July 2026, Prime Minister Anutin Charnvirakul visited the site to monitor the situation, saying the accumulated water remained under control while instructing relevant agencies to resolve the problem quickly to ensure public safety.
When reporters visited the site on the morning of 9 July 2026, engineers and officials from the Mass Rapid Transit Authority of Thailand (MRTA) were continuing to monitor conditions.
MRTA Chairman Montri Dechasakulsom said preliminary assessments indicate the leak originated from a defect in the project’s sump pit, where groundwater is collected before being pumped out.
He said engineers immediately began sealing the leak while continuously pumping water to prevent additional inflow.
According to the MRTA, groundwater entered the construction site at a rate of about 70 cubic metres per hour overnight. By the morning, the inflow had fallen to approximately 50 cubic metres per hour, indicating that the situation was improving.
Montri stressed that the incident is unrelated to a previous groundwater leak reported at another construction site in Samsen, describing the latest case as a construction defect. The contractor has been instructed to complete repairs as quickly as possible.
To reduce groundwater pressure, the MRTA has ordered additional dewatering measures, including drilling 50-metre-deep wells to draw groundwater away from the site. Grouting work to seal the leak has already been completed, while construction of an underground curtain wall is underway to prevent further seepage and minimise impacts on surrounding properties.
Officials said inspections have found no additional ground subsidence, structural tilting or new cracks. A nearby pedestrian bridge remains structurally sound, while district engineers have been asked to inspect surrounding buildings to reassure residents.
Responding to reports of cracks in nearby buildings and roads, Montri said some cracks predated the incident. However, contractors have been instructed to conduct detailed inspections of every building in the affected area alongside district engineering officials.
The additional groundwater pumping system is expected to begin operating on 9 July 2026, with water extraction scheduled to start on 10 July 2026. Construction of the underground curtain wall is expected to be completed within about one week.
The southern Purple Line MRT project remains on schedule for completion by the end of 2027, officials said, adding that the situation remains under control and is being monitored around the clock.
To facilitate repair work, authorities initially closed the two leftmost outbound lanes on Prajadhipok Road. From 11:00 on 9 July 2026, all traffic from Ban Khaek Intersection to Wongwian Yai via Prajadhipok Road was closed, with vehicles diverted onto the inbound carriageway.
Nearby residents expressed concern following the incident.
Beam, a 28-year-old beverage vendor whose shop is close to the construction site, said he worries that the leak could worsen existing structural damage after the recent earthquake.
He said he has operated his business in the area for about a year and has noticed gradual ground settlement, heavy dust from construction and strong vibrations during excavation and piling work.
Beam urged authorities to thoroughly inspect the area and ensure public safety, noting that the road is heavily used by commuters. He also showed reporters a crack beside a nearby building, saying it had appeared only recently after water seeped into the tunnel construction site.
