A dramatic hole swallowed a part of a central road to Bangkok on September 24, forcing the Massive Traffic Authority of Thailand (MRTA) to detain the construction of the metro metro extension of $ 2.2 billion from the city and command the emergency stabilization.
In a technical update of September 25, Mrta stated that the soil and water are infiltrated through a gap in the interface of the station-station at Vajira Hospital station, mining the stacked twin tunnels 6.30 meters in diameter.
The collapse was aggravated by the rupture of a 1.2 m water major, which accelerated the loss of the soil and triggered the failure of the pavement. The authority stated that “the subsidence was observed before there was a complete failure of the pavement” and pledged to restore traffic before moving to long -term structural repairs.
Authorities said that no deaths or injuries did not occur, and the morning time limiting traffic to Samsen Road. The rupture of the water led to flooding and service interruptions located; A nearby police station was evacuated and sealed until the inspections were completed.
Local media reported that Governor Chadchart Sittipunt described the breach as about 30 m² in size, saying that the crews are aimed at a reopening of October 8 in Samsen Road, using sprayed concrete stabilization layers, sand filling and crushed stone.
Police have launched an investigation into the incident, according to the Bangkok PostWith local sales outlets reported that the governor stated the area of a disaster to accelerate the response.
Bangkok is on top of thick layers of soft Holocene clay than the older Pleistocene and Pliocene overdrops, a geological profile that contributes to generalized land subsidence and complicates underground construction.
The Vajira Hospital, which was directly facing the site, had suspended outpatient services for two days, but “hospitalized services continued without IBRNTERRUPTION,” a statement said after the road failure. Normal operations resumed on September 26.
Purple line extension
Work on the southern extension of Bangkok’s purple line, divided into six civil work contracts, which took place in March 2022. Aecom named the project designer, says that the 14.3 miles plan is expected to end in 2027.
Bangkok is on top of thick layers of soft Holocene clay than the older Pleistocene and Pliocene overdrops, a geological profile that contributes to generalized land subsidence and complicates underground construction. Image courtesy of Researchgate
The planning of the line was formed with the early support of the Asian Development Bank, which provided technical assistance from 2017 for due diligence due to engineering, hiring, environment and resettlement problems.
Although Thailand finally decreased by ADB funding, the bank’s work resulted in recommendations for multimodal integration and harmonization of rates that fueled the government transport policy. The joint company CST-PL is responsible for the Vajira Hospital’s segment, with PMCSC-1 as owner engineer.
According to ThailandOne in English daily in Bangkok, the project is now more than 60% complete.
The line will connect Tao Poon a Rat Burana with a mixture of high, underground track designed to relieve congestion in the dense central districts of the capital.
MRTA reported that about 500 m³ of sand bags were placed on a diaphragm wall to block the entrances before climbing the area with a concrete mat of 3 to 4 m thick and refilling to stabilize the road.
Political scrutiny has intensified when the former Deputy Governor Samart Ratchapolsit accused Mrta of “trying to avoid responsibility” and demanding accounts, citing the contractor’s links to political leaders.
The collapse comes from the difficulties that contractors in underground construction in Bangkok’s soft alluvial soils and elevated levels of groundwater, where strong seasonal rains can further destabilize the terrain. The Japan International Cooperation Agency has previously identified these main challenges to expand the city’s mass traffic system.
An equal reviewed study published in Sustainability In 2022 he came to a similar conclusion, warning that “groundwater pumping has induced long -term settlement in the Bangkok Metropolitan Region, with registered subsidence rates reaching 10 cm per year during the maximum extraction in the 1980’s” and that monitoring lagoons continue to leave vulnerable underground works.
The incident also highlights the vulnerability of the station interfaces -the impact of the cascade of the utility breaks and the confidence in the sand bag and the mass concrete as methods of emergency stabilization.
With CST-PL and MRTA under pressure to reopen the road, the questions about the long-term impacts are kept in the purple line delivery schedule and if control and supervision were adequate before the collapse.
