China Railway 12th Bureau was constructing a tunnel in Northeast Chongqing when an explosion accident occurred in the afternoon of March 30th. According to official reports on March 31st, the accident resulted in the death of 4 people and injuries to 9 others.
The Wan Zhou District Transportation Commission of Chongqing released a situation report stating that around 3:10 pm on the 30th, an explosion accident suspected to be caused by flammable gas occurred in the left tunnel of the Iron Peak Mountain Tunnel on the Enshi to Guangyuan National Highway Wan Zhou to Kaijiang section (A2 contract section), invested by Chongqing Wan Kai Da Expressway Co., Ltd. and constructed by China Railway 12th Bureau Group Co., Ltd., resulting in 1 missing person and 12 injuries at the scene.
By midnight on March 31st, the missing person was found but showed no signs of life, and 3 others were declared dead after unsuccessful rescue efforts. Currently, the construction site involved has been shut down.
The Iron Peak Mountain Tunnel is located between Wan Zhou District and Kai Zhou District of Chongqing, being the longest municipal mountain tunnel in China and a crucial project on the Wan Kai Da Expressway (G5012 Enshi to Guangyuan National Highway Chongqing section). The left tunnel is 8,635 meters long, the right tunnel is 8,614 meters long, totaling 17,249 meters. The tunnel began construction on February 20, 2023, and is expected to be completed by 2027.
Earlier this year, China Railway 12th Bureau also had an accident during construction. On February 2nd at 5:46 pm, the Lianshen Line Yu Gang Bridge, constructed by China Railway 12th Bureau, collapsed during construction, resulting in the death of 5 people.
On September 1, 2025, a tower crane collapsed at a construction site of Chengdu Chenghua China Railway 22nd Bureau, resulting in the deaths of 5 people.
Public records show that China Railway 12th Bureau Group Co., Ltd., formerly known as the Second Brigade of Railway Troops, collectively transferred to civil work in 1984 and renamed as the 12th Engineering Bureau of the Railway Ministry. In 1998, it was restructured and formed as a corporate group. It is currently a wholly-owned subsidiary of China Railway Construction Corporation, one of the Fortune Global 500 companies, with Li Tiansheng as the Chairman.