Chiang Rai, Thailand
Two construction workers died and seven others were injured after scaffolding collapsed inside the Doi Luang railway tunnel on the evening of Saturday, June 20th, 2026, during ongoing work on the State Railway of Thailand’s (SRT) Den Chai-Chiang Rai-Chiang Khong line.
The incident occurred around 4:30–6:00 p.m. (local time) in the 3.4-kilometer-long Doi Luang tunnel, located in Doi Luang district, Chiang Rai province. This tunnel forms part of Contract 3 (Chiang Rai to Chiang Khong section) of the major northern railway project linking Den Chai in Phrae province to Chiang Khong on the Thai-Lao border. The tunnel was successfully bored through last year; current work focuses on installing the permanent concrete lining, waterproofing systems, and related infrastructure, with more than three-quarters of the lining reportedly complete at the time of the accident.
According to Thai media reports and official statements, workers were installing a waterproofing membrane system when rocks suddenly fell from the tunnel wall. This triggered the collapse of scaffolding and associated equipment, which fell onto the workers below. Earlier local accounts initially described it as a collapse in the sprayed concrete work area.
Deputy Transport Minister Siripong Angkasakulkiat confirmed that authorities received the initial report at approximately 8:35 p.m. He stated that the preliminary cause appeared to be falling rocks from the tunnel wall during waterproofing installation. The site has been secured, the accident area sealed off, and a full investigation is underway.
Project engineer Pattapong Boonkaew described the event as an “unforeseeable geological event,” noting that the collapse happened in an unlined section of the tunnel awaiting protective treatment. Some Thai reports suggested heavy rainfall and water accumulation in rock layers as a contributing factor.
The two deceased workers were killed at the scene. Injured workers, reports indicate between three seriously hurt and four with minor injuries, were transported to a local hospital. The SRT has expressed condolences, temporarily halted work at the site (initially for at least two days), and is coordinating compensation and further safety reviews.
The Den Chai-Chiang Rai-Chiang Khong project is a major double-track railway initiative designed at improving connectivity in northern Thailand and facilitating cross-border links with Laos.
Officials have stated that the main tunnel structure remains stable and that the incident is not expected to affect the long-term integrity of the completed tunnel. Investigations continue to determine exact contributing factors and any necessary safety enhancements.
For the original version of this article, please visit The Pattaya News.
