Rama II road collapse: TSEA president outlines 4 possible causes

Following the subsidence incident on Rama II Road on Saturday (January 17), which caused a vehicle to fall into a hole, Amorn Pimanmas, President of the Thailand Structural Engineers Association (TSEA), has provided an initial assessment, highlighting four key factors that may have contributed to the event.

Four possible causes: From soil flow to pipe failure

Amorn pointed out that, while the exact cause is still under investigation, the presence of ongoing construction and nearby piping close to the subsidence site suggests the following possible explanations:

• Soil flow into construction pit: The installation of sheet piling near the subsidence point may have allowed soil beneath the road to flow into the construction pit, forming a void.
   
• Water carrying sand: If the sheet piling was not deeply enough embedded, water could have carried the upper sandy soil into the pit from above.
   
• Clay soil movement: If the sheet piling was not sufficiently deep, weak clay layers beneath the road may have shifted and moved into the pit.
   
• Pipe failure: A broken water pipe in the area might have caused water to erode the underlying soil layers beneath the road.

A costly lesson: Prevent a repeat of the Vajira Hospital incident

This event has drawn comparisons to the large sinkhole that occurred on Samsen Road, in front of Vajira Hospital, in September 2025. That incident, caused by the construction of a subway station, highlighted the risks of building in soft clay soil. 

Amorn stressed that construction in such areas requires extra care, including robust soil retaining systems to prevent shifts in the ground.

The TSEA president is scheduled to visit the Rama II Road subsidence site at 4pm today, following an inspection of a crane collapse earlier in the afternoon, in order to gather conclusive evidence and propose preventive measures to avoid future incidents on this stretch of road.