Thailand, June 2026 — Two construction workers were killed and seven others injured after scaffolding collapsed inside the Doi Luang railway tunnel during construction of the Den Chai–Chiang Rai–Chiang Khong railway line. Initial reports indicate the incident occurred while workers were installing a waterproofing system, with falling rock from the tunnel wall believed to have triggered the collapse, although the exact cause remains under investigation.
The accident occurred in the 3.4 km Doi Luang tunnel, part of Contract 3 of the Chiang Rai–Chiang Khong section of the project. The contract covers approximately 87 km of railway infrastructure, including at-grade and elevated tracks, three stations, three halts, signalling and telecommunications systems, and related works. The project is being delivered by the CKST-DC3 Joint Venture, comprising CH. Karnchang, Sino-Thai Engineering & Construction, and Chiangmai Construction.
Following the incident, the State Railway of Thailand (SRT) secured the construction site and ordered an immediate suspension of works to allow engineers and safety authorities to inspect the tunnel and determine the cause of the collapse. The Ministry of Transport has also initiated a detailed investigation, reinforcing the importance of stringent safety management during complex underground rail construction.
The accident highlights the engineering and safety challenges associated with large-scale tunnel projects, particularly those involving underground excavation and structural support installations. As Thailand continues expanding its national railway network, the findings of the investigation are expected to inform future construction safety protocols and risk management practices across major infrastructure projects.
The Den Chai–Chiang Rai–Chiang Khong railway is a strategic project intended to improve passenger and freight connectivity across northern Thailand while strengthening links to regional trade corridors. Ensuring robust construction safety will remain essential to maintaining project delivery schedules and safeguarding workers as the country's railway expansion progresses.
Source: The Star (The Nation/ANN)
Fatal Tunnel Construction Accident Halts Thailand Rail Project Works
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Construction safety remains a critical priority as countries accelerate investment in major railway infrastructure projects. A fatal scaffolding collapse at a railway tunnel construction site in northern Thailand has prompted authorities to suspend work temporarily while investigations into the cause are underway.
