The final weld on the north channel span of the Hangzhou Bay Cross-Sea Railway Bridge was completed on Tuesday, marking a major milestone in the construction of what is set to become the world's longest cross-sea railway bridge.
The closure was completed 570 meters offshore from Haiyan county in Zhejiang province, where workers welded the final section of the central closure segment. The milestone means construction of the bridge's main structure has entered its final stage.
"Overall progress on the Hangzhou Bay Cross-Sea Railway Bridge has now exceeded 90 percent," said Luo Yunfeng, project commander with Shanghai State Railway Engineering Construction Management Co Ltd. "We're transitioning rapidly from large-scale structural work to the final stages, completing the main structure and installing the bridge deck system."
The 29.2-kilometer-long bridge carries two railway tracks across Hangzhou Bay and serves as a key link in the Nantong-Ningbo high-speed railway. Designed for trains traveling at speeds of up to 350 kilometers per hour, it connects Haiyan county in Jiaxing, Zhejiang province, with Cixi, a county-level city administered by Ningbo. It is located upstream of the existing Hangzhou Bay highway bridge.
The bridge comprises three main channel bridges — north, central and south — as well as approach bridges across shallow and deep waters.
The north channel bridge is a cable-stayed structure with a main span of 450 meters, which Luo said is the longest span for a high-speed railway bridge with ballastless track currently under construction worldwide. The bridge is 932.7 meters long and features a hybrid steel box-truss girder design, with a steel box girder below and steel trusses above.
"A 450-meter span represents an entirely new technical challenge," said Wang Yinfeng, deputy project manager with China Railway Major Bridge Engineering Group Co Ltd. "The core difficulty lies in controlling deformation of such a long, flexible structure within the millimeter-level precision required by high-speed track systems."
Hangzhou Bay's strong tides, swift currents and high winds pose significant challenges to bridge construction. The relatively shallow waters at the north channel site also required crews to schedule steel girder installations carefully around tidal cycles while contending with strong currents, Wang said.
To cope with the demanding marine conditions, project teams used integrated bridge-track alignment control technology, intelligent data collection and continuous real-time monitoring throughout manufacturing and assembly to ensure precise alignment during closure.
The south channel bridge was closed on Oct 17, while closure of the central channel bridge is expected by late November. With the north channel span now connected, workers will focus on installing bridge deck accessories and laying ballastless tracks.
The Nantong-Ningbo high-speed railway is a key part of China's "eight vertical and eight horizontal" high-speed rail network. The line will serve 11 stations and connect with several existing railway lines.
"Once operational, the railway will bring rail service to Haiyan for the first time and high-speed rail to Cixi," Luo said. "The bridge will enable trains to cross directly over the sea, strengthening the integrated transportation network across the Yangtze River Delta region."
Editor：Zhou Jinmiao
