The Wanzhou District Transportation Commission in Chongqing issued a statement on March 31 confirming an explosion. At approximately 3:10 p.m. on March 30, a suspected combustible gas explosion occurred in the left bore of the Tiefengshan Tunnel, which was under active construction in northeastern Chongqing. The initial report listed one worker missing and twelve injured.
By midnight on March 31, search crews had recovered the missing worker’s body. Three other workers died of their injuries in the hospital. The construction site has been shut down, families are being notified, and an investigation is underway.
The Tiefengshan Tunnel sits between Chongqing’s Wanzhou and Kaizhou districts. It is the longest municipal mountain tunnel in China, and the most difficult section of the Wan-Kai-Da Expressway, which forms part of the G5012 national expressway linking Enshi to Guangyuan. The tunnel’s left bore runs 8,635 meters, the right bore 8,614 meters, for a combined length of 17,249 meters. The project is funded by Chongqing Wankaida Expressway Co. and built by China Railway 12th Bureau Group. Construction began on Feb. 20, 2023, with completion scheduled for 2027.
The Tiefengshan explosion is far from an isolated incident. On Feb. 2, 2026, a tied-arch girder collapsed during concrete pouring at the Yuegang Bridge on the Jiangsu Lianshen Line, another China Railway 12th Bureau project. Five workers died.
On March 2, 2021, a crane accident at the Jing-Tang Line No. 4 mixing station in Tianjin, also built by the 12th Bureau, killed one worker during a lifting operation.
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The pattern points to recurring failures in construction safety across tunnel boring, high-altitude work, and heavy equipment operations.
The parent company, CRCC, has its own trail of fatal projects
China Railway 12th Bureau Group is a wholly owned subsidiary of China Railway Construction Corporation (CRCC), a state-owned conglomerate managed by China’s State-owned Assets Supervision and Administration Commission (SASAC). Headquartered in Taiyuan, Shanxi Province, the 12th Bureau traces its origins to the Second Division of the Railway Corps, the military engineering unit that built much of China’s rail network. It holds the highest-tier construction qualifications for railway, highway, building, and municipal engineering.
CRCC itself, one of the largest engineering contractors on earth, has its own record of fatal incidents. In January 2026, a crane collapsed at a China-Thailand high-speed rail project jointly built by CRCC and Thailand’s Italian-Thai Development, killing two workers and injuring five. Last March, the Bangkok National Audit Office building, also built by the same CRCC-Italian-Thai partnership, collapsed during an earthquake.
In August 2025, a steel cable snapped during tensioning work on the Jianzha Yellow River Bridge in Qinghai Province, part of the Sichuan-Qinghai Railway. The bridge was being built by CRCC’s subsidiary China Railway Major Bridge Engineering Group. The failure caused a 108-meter steel arch to collapse, killing twelve workers. Four others were never found.
The string of accidents has fueled public fury on Chinese social media. “China Railway again!” one commenter wrote. “Has China Railway gone completely reckless these last couple years?” asked another. Others cut closer to the bone: “Is our infrastructure sector falling apart?” and “Officials steal, contractors cut corners. Of course there are accidents.”
