Recently, the Nan Niwan Airport Bridge on the Yan’an East Ring Expressway — invested and constructed by China Energy Engineering Co., Ltd. and undertaken by China Railway Seventh Group — successfully completed a smooth, high-altitude rotation at a height of 54.5 meters. The 25,000-ton T-shaped rigid-frame girder bridge was rotated by 77.49 degrees, achieving millimeter-level precision alignment.

The Nan Niwan Airport Bridge has a total length of 638 m and spans multiple key transport routes, including the Baotou-Xi'an Railway, Xi'an-Yan'an High-speed Railway, and three major highways. During construction, the project faced several world-class engineering challenges: with a bridge height of 67 m and a rotation height of 54.5 m — both setting records among similar structures. The 25,000-ton rotation mass is equivalent to lifting three Eiffel Towers at a height comparable to a 23-story building. The bridge also spans both an electrified railway and a high-speed rail line, making construction safety risks extremely high.

To minimize interference with railway operations, the project team conducted multiple rounds of expert reviews and optimization, ultimately adopting a construction plan of “cantilever casting parallel to the railway, followed by integral rotation.” The rotation system employed an internationally advanced spherical hinge bearing structure weighing 33 t. The bridge was equipped with a “digital twin + real-time monitoring” system, using embedded sensors and an intelligent control platform to transmit stress and deformation data throughout the rotation process, enabling fully automated, data-driven control. The precise rotation was completed within the designated “railway operation window” period.

The Yan’an East Ring Expressway stretches 56.8 km and is a key component of Shaanxi Province’s highway network as well as a major construction project under the 14th Five-Year Plan, with a total investment of 8.688 billion yuan. The expressway is designed as a four-lane highway with a design speed of 100 km/h and a roadbed width of 26 m.

Upon completion, the project will effectively connect Yan’an New District with Nan Niwan Airport, divert 70% of transit traffic, and eliminate the traffic bottleneck of Y-shaped valley urban area of Yan’an. Together with the Baotou–Maoming Expressway and Changzhi-Yan'an Expressway, it will form a high-speed loop around central Yan’an and a new north–south corridor between Yulin and Xi’an, completing the “three vertical, two horizontal, one connecting, and one ring” highway framework of Yan’an.