Bangkok evacuates 60 people within 30 metres of Purple Line subsidence

Bangkok evacuates 60 people as tunnel leak threatens buildings

Bangkok authorities have evacuated about 60 people from three commercial buildings within a 30-metre safety zone around a subsidence site near Wongwian Yai, with residents expected to remain in temporary accommodation for about one week.

A roughly 200-metre section of Prajadhipok Road between Ban Khaek intersection and Wongwian Yai has also been closed as a precaution, while real-time sensors have been installed on nearby buildings to detect any movement that could indicate further structural risk.

The emergency measures followed water seepage inside a drainage sump at the lowest point of the southern Purple Line construction tunnel. The leak allowed surrounding soil to flow into the underground structure, causing the ground and road surface above to subside and raising concerns about neighbouring buildings.

Bangkok Governor Chadchart Sittipunt inspected the area on July 9 with Deputy Governor Wisanu Subsompon and Deputy Permanent Secretary Kanokwan Iamlim. Authorities reported that the water level and rate of subsidence had begun to stabilise, but said round-the-clock monitoring would continue.

Residents moved out for one week

The Bangkok Metropolitan Administration and the project contractor ordered the evacuation of approximately 60 residents from three commercial buildings located within 30 metres of the damaged road surface.

The residents were transferred to temporary accommodation, including hotels, and are expected to remain away from the buildings for around one week. The Mass Rapid Transit Authority of Thailand’s contractor will cover accommodation, compensation and other related expenses.

Officials will assess the stability of the buildings and surrounding infrastructure before allowing residents to return or easing any of the restrictions.

Real-time sensors monitor building movement

The Department of Disaster Prevention and Mitigation installed two Rescue Guardian monitoring units on buildings close to the affected area.

The equipment measures tilting and structural movement in real time and transmits the information to a monitoring system. An immediate warning will be issued if abnormal movement is detected. The sensors were placed within about 30 metres of cracks found in the road surface.

Engineers from Thailand’s national Urban Search and Rescue team have also joined the inspection to evaluate surrounding structures and ensure that the response follows engineering and public-safety standards.

The Department of Disaster Prevention and Mitigation deployed generators, lighting equipment and other specialised machinery to support overnight operations. Rescue foundations and volunteers were placed on standby in case emergency medical assistance or patient transfers became necessary.

Command centre established at the site

A forward command centre has been set up near the subsidence point to coordinate work among the BMA, the MRTA, the contractor, district authorities, police and emergency-response teams.

The immediate priority is to seal the leak and prevent additional soil from being drawn into the tunnel. Instruments are being used continuously to monitor the road surface, soil movement, water leakage and the condition of nearby buildings.

The affected tunnel forms part of the same southern Purple Line alignment as the section near Vajira Hospital where an earlier road collapse occurred, although the construction work is being undertaken by a different contractor.

Prajadhipok Road closed for about 200 metres

All outbound lanes of Prajadhipok Road from Ban Khaek intersection towards the King Taksin the Great Monument at Wongwian Yai have been closed over a distance of approximately 200 metres.

The closure is intended to reduce traffic vibration that could further destabilise the soil or affect nearby buildings. Two inbound lanes have been converted temporarily for outbound vehicles.

Motorists arriving from Memorial Bridge or Phra Pok Klao Bridge have been advised to turn at Ban Khaek intersection and use Itsaraphap, Lat Ya or Somdet Chao Phraya roads instead.

Measures planned for nearby schools

Authorities are also assessing the longer-term traffic impact because the area is a major bottleneck near large schools, including Suankularb Wittayalai School and Suksanari School.

Chadchart indicated that Bangkok may adopt measures previously used following the subsidence near Vajira Hospital, potentially including additional school shuttle services to reduce the number of parents’ vehicles entering the area. Further traffic arrangements will be announced once officials determine how long the closure must remain in place.

The BMA and the Department of Disaster Prevention and Mitigation said restrictions would be eased only after engineers had confirmed that the buildings, road and surrounding infrastructure were safe.