A worker operates at the construction site of the Lisi Village Bridge on the Chongqing section of the Yichang–Fuling High-Speed Railway. (Photo/Xinhua)

Chongqing - As scorching summer temperatures bake southwestern China, construction crews on three major Chongqing railway projects are being shielded from extreme heat through mist-spraying systems, staggered shifts and concrete-cooling plants.

At the redevelopment site of Chongqing Railway Station, two 10-meter-high automated spray towers rotate 360 degrees, covering a 30-meter radius with fine mist. A tower crane adds another cooling layer, backed by 100 fixed sprinklers. 

Fog cannons and water trucks patrolling every two hours have reduced perceived temperatures by 5 to 10 degrees, said Wang Ganglong, deputy production manager at China Railway 11th Bureau.

"It keeps the air moist and takes the scorch off the ground," said welder Liu Gangan. The station, known locally as Caiyuanba, is being overhauled with over 200 workers on site.

At the 404-meter Lisicun Bridge in Fuling District, part of the Yichang-Fuling high-speed railway, crews use three air-conditioned rest stops offering mung bean soup and iced drinks. 

Rebar worker Li Baoguo reported that his team completes nearly 400 steel bar bindings daily. "The bars get hot enough to fry an egg," he joked. After finishing a round, he headed to a stop, downed a bowl of soup, and sighed with relief. "Free soup and medicine give us peace of mind."

To shield workers from peak heat, the project has rolled out a staggered shift schedule, with crews starting at 6 a.m., knocking off by 10 a.m., and resuming at 4 p.m. 

Beyond the shelters and adjusted hours, the site has layered on additional safeguards. Party representatives conduct daily wellness checks, while volunteer teams deliver cooling supplies to elevated platforms and tunnel faces, accompanied by on-the-spot safety briefings.

Inside the 14.78-km Tiefengshan tunnel, part of the Xi'an-Chongqing high-speed railway, concrete quality is critical as the final push nears. "High temperatures are concrete's worst enemy," said site manager Xia Wujun. "Even slight deviations can cause temperature cracks and compromise structural safety."

At the Wanzhou batching plant, an intelligent system uses air blowers, water chillers, and ice makers to produce over 10 tons of ice daily. The system pre-cools aggregates in an enclosed chamber and chills mixing water. Sensors feed data to a central unit that automatically adjusts the output. 

Concrete discharge temperatures remain below 30°C—a 10-degree reduction that eliminates the risk of cracking, according to Xia.