CHIANG RAI — A major infrastructure project was halted in tragedy on Saturday evening when a massive scaffolding structure collapsed deep inside the Doi Luang railway tunnel, killing two workers and leaving seven others injured.

The incident occurred at approximately 8:00 p.m. on June 20, 2026 inside the tunnel, which is currently being excavated as part of the State Railway of Thailand’s (SRT) multi-billion-baht Den Chai–Chiang Rai–Chiang Khong railway line.

According to site supervisors, a team of laborers was working on a high section of the tunnel lining when the heavy metal scaffolding suddenly buckled under immense weight, sending steel pipes, planks, and concrete wet-mix crashing down onto the workers below.

Emergency medical teams, disaster response units, and local police rushed to the construction site in the Doi Luang district. Because the accident occurred deep within the subterranean excavation zone, rescue workers had to navigate limited visibility and cramped spaces to reach the trapped laborers.

Paramedics confirmed that two workers sustained fatal crush injuries and were pronounced dead at the scene. Emergency crews worked frantically for over an hour to clear twisted steel debris to free the remaining survivors.

Of the injured workers, three suffered major trauma, including bone fractures and severe lacerations, and were rushed to a provincial hospital for urgent treatment. Meanwhile, the remaining four laborers sustained minor cuts and bruises and were treated by medical personnel directly at the site.

The Den Chai–Chiang Rai–Chiang Khong railway line is one of Thailand's most ambitious infrastructure projects, designed to connect Northern provinces to the Laotian border to boost trade and tourism. However, this fatal incident has raised immediate questions regarding underground construction safety protocols.

Following the collapse, engineering inspectors from the Department of Rail Transport and structural experts were dispatched to the site. A preliminary investigation is focusing on whether the scaffolding was overloaded beyond its structural capacity or if the tunnel's shifting geology played a role in destabilizing the platform.

The State Railway of Thailand expressed its deepest condolences to the families of the victims. SRT officials announced that construction inside the Doi Luang tunnel has been strictly suspended until a thorough forensic engineering investigation is completed and enhanced safety measures are implemented.