Chongqi rail and road bridge hits milestone

The main span of the Chongqi Rail-Road Yangtze River Bridge was successfully installed on Tuesday, marking a major milestone for what will become the world's largest cable-stayed bridge combining ballastless railway tracks and highway infrastructure.

The 4.09-kilometer bridge spans the northern branch of the Yangtze River estuary and features a 400-meter main span.

Its double-deck design accommodates a six-lane highway with a design speed of 100 kilometers per hour on the upper level, while the lower deck will carry two high-speed railway lines supporting trains traveling at 350 km/h, alongside intercity railway lines designed for operations at 250 km/h.

The bridge is a key component of the Shanghai-Chongqing-Chengdu high-speed railway corridor.

It is both the world's largest rail-highway cable-stayed bridge under construction and China's first rail-highway Yangtze River bridge designed to accommodate 350 km/h high-speed trains.

"This bridge is the key control project of the Qidong-Taicang section in Jiangsu province," said Yin Xueguo, commander of Chongming operations at the Shanghai State Railway Engineering Construction Management Co."Today's milestone is of great significance to the overall construction schedule."

Construction teams will now focus on installing bridge deck systems, ballastless tracks and auxiliary electrical facilities, with the bridge expected to be fully operational by the end of 2027, Yin said.

Hu Huiyue, chief designer of the bridge at the China Railway Major Bridge Reconnaissance & Design Institute Co, said integrating highway and railway infrastructure within a single structure posed unique engineering challenges.

"The highway and railway share construction space within the bridge area before separating to facilitate rapid traffic distribution and improve the efficiency of the transportation hub," Hu said.

"Our structural innovations include integrating the main and auxiliary spans to save space while optimizing bridge height to achieve a better performance balance for the 350 kilometers per hour ballastless track system," he added.

Since drilling work began in December 2022, construction teams have overcome numerous challenges, including complex waterway conditions, ultra-large-span installation work and stringent precision requirements.

The project pioneered the use of intelligent grouting technology for both pile bottoms and pile sides in domestic railway bridge construction, ensuring secure anchoring of 152 bored piles, each with a diameter of 2.5 meters, across the two main piers.

Construction adopted a single-cantilever method using two 1,100-metric-ton beam-lifting cranes integrated with intelligent monitoring systems. The digital systems continuously tracked steel beam positioning, structural stress and deformation while automatically adjusting lifting operations.

"Our two construction approaches successfully addressed world-class engineering challenges in single-cantilever installation and long-distance launching," said Xiong Kaibing, project manager at the China Railway Major Bridge Engineering Group Co.

"More importantly, through advanced data integration and system coordination, we achieved the high-precision bidirectional convergence that made today's successful closure possible," he said.

Upon completion, the bridge will significantly improve regional connectivity, reducing travel time between Shanghai and Qidong in Jiangsu province from two and a half hours to less than 30 minutes by rail.

The project is expected to strengthen the comprehensive transportation corridor along the Yangtze River Economic Belt and support deeper integration of the Yangtze River Delta region.