PM Inspects Purple Line Leak in Bangkok

Prime Minister Anutin Charnvirakul visited the southern Purple Line construction site at Wongwian Yai late on Wednesday night, 8 July 2026, after heavy rain caused water to leak into an underground tunnel section, prompting an urgent inspection by government officials and engineers. Authorities said the leak was under control, with pumping operations successfully preventing water levels from rising further.

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The leak occurred inside a construction shaft on the Tao Poon-Rat Burana, or Kanchanaphisek Ring Road, section of the Purple Line extension after heavy rainfall across Bangkok on July 8. Water entered the worksite during the day, leading transport officials to assess the safety of the tunnel and nearby structures.

MRTA board chairman Montri Dechasakulsom said preliminary findings suggested the leak originated from a defect in the project’s sump pit, rather than a cause similar to the earlier tunnel collapse near Vajira Hospital. He said contractors immediately began repairs, focusing on preventing additional water from entering the site while maintaining continuous pumping.

According to Montri, water inflow reached around 70 cubic metres per hour overnight before falling to about 50 cubic metres per hour by Thursday morning, indicating that the situation was improving. He stressed that current pumping capacity was sufficient to handle the remaining inflow.

Before the prime minister’s arrival, Deputy Prime Minister and Transport Minister Phiphat Ratchakitprakarn, Deputy Transport Ministers Siripong Angsakulkiat, Phattharaphong Phatraprasit and Sanphet Boonyamanee, together with Deputy Interior Minister Worasit Liangprasit, inspected the site. They were joined by MRTA governor Gardphajon Udomdhammabhakdi and Prasong Suviwattanachai, executive chairman and managing director of Unique Engineering and Construction Public Company Limited.

The affected area forms part of Contract 4 of the southern Purple Line project, covering the Saphan Phut-Dao Khanong section. The 14.982-billion-baht contract is being carried out by Unique Engineering and Construction Public Company Limited (UNIQ), with work focused on tunnel excavation and retaining wall construction.

Phattharaphong ordered the MRTA and the contractor to carry out a full technical assessment, determine the exact cause of the leak and implement urgent corrective measures to protect the tunnel, public safety and the construction schedule. He also instructed them to provide regular progress reports to the Transport Ministry and ensure all work complied with engineering and safety standards.

Pictures courtesy of The Nation

Anutin said engineers were addressing both immediate repairs and long-term prevention. “At this stage, we can control the water level,” he said, adding that road closures were not required and that the leak differed from the earlier tunnel collapse because it had been detected early.

Montri said the MRTA would install additional dewatering systems, including 50-metre-deep wells to reduce groundwater pressure, while grout injections had already been completed around the sump pit. Construction of an underground curtain wall is expected to be completed within about one week to prevent further groundwater seepage.

He added that inspections had found no new ground subsidence, structural movement or fresh cracks, including on a nearby pedestrian bridge. District engineers will continue inspecting surrounding buildings, while monitoring equipment remains in place to detect any movement.

The Nation reported that the Purple Line extension remains scheduled for completion by the end of 2027. Officials said repairs and monitoring would continue around the clock to ensure construction safety and maintain public confidence.

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10 July 2026