The 1,821-meter Yanbei Viaduct on Urumqi's East Second Ring Road will use the horizontal rotation method for its section crossing the Lanzhou-Xinjiang Railway. During construction, a 17,000-ton bridge body will be rotated 69° within 60 minutes.
　　On July 19, at the construction section of the Yanbei Viaduct crossing the Lanzhou-Xinjiang Railway in Urumqi, the piers have taken shape, and workers are busy constructing. Photo by Reporter Xie Peng
　　It is reported that this rotation is the largest-tonnage rotating bridge in Northwest China. Currently, no single-span integral rotating bridge in the Northwest region has exceeded 10,000 tons.
　　Reducing the impact on Lanzhou-Xinjiang Railway operations
　　“The Yanbei Viaduct crosses the Lanzhou-Xinjiang Railway, Hongyanchi North Road, Yan'erwo Road, Hetan Expressway, and Yashan Middle Road. The section crossing the Lanzhou-Xinjiang Railway adopts horizontal rotation construction, which will greatly reduce the impact on Lanzhou-Xinjiang Railway operations and shorten the construction period,” introduced Liu Qingfeng, director of the East Second Ring Road Project Command. When crossing urban main roads, this method features short, smooth, and quick support erection, convenient pre-set openings for traffic diversion, meets traffic management department requirements for ensuring rapid vehicle passage, and can alleviate traffic pressure.
　　The Yanbei Viaduct is located on Urumqi's East Second Ring Road. Construction officially started in August 2016, with the main structure planned to be completed in October 2018. The main line is 43.079 kilometers long, with eight lanes in both directions and a design speed of 80 km/h. Currently, the rotation construction method has been confirmed for the section of the Yanbei Viaduct crossing the Lanzhou-Xinjiang Railway, and it is in the design drawing stage.
　　“The Yanbei Viaduct is located in Urumqi's wind gap area, where the maximum wind speed can reach Level 12. Considering safety, construction period, and other factors, the cast-in-place box girder construction adopts the steel pipe Bailey beam column support method, which can overcome the above difficulties and is particularly suitable for cast-in-place box girder construction on high piers,” introduced Liu Gang, chief engineer of the Second Bid Section of the Urumqi East Second Ring Road Project of CCCC First Highway Engineering Co., Ltd. The Yanbei Viaduct has 55 spans, of which 31 are cast-in-place box girders, the highest on the entire line and a rare high-pier cast-in-place structure in the city. The maximum span is 55 meters, and the highest pier is 33 meters.
　　Railway to be closed during formal rotating bridge erection
　　The reporter learned that the rotating bridge erection will be divided into two rotations: a trial rotation and a formal rotation. During construction, the trial rotation will first be 8°, at which time the minimum distance between the girder body and the center of the existing Lanzhou-Xinjiang Railway line will be about 12.25 meters.
　　During the formal rotation, the railway must be closed. The rotation angle is 69°, expected to take 60 minutes. The total time required for alignment adjustment, elevation adjustment, and positioning is 120 minutes, not exceeding 150 minutes.
　　“That is to say, the girder body will first undergo an 8° rotation as a test. After all aspects meet requirements without deviation, the formal 69° rotation will be carried out, taking 60 minutes. Later, there will be some alignment adjustment, elevation adjustment, and positioning work,” said Zhang Tao, engineering director of the work area of the Second Bid Section of the East Second Ring Road Project of CCCC First Highway Engineering Co., Ltd.
　　It is understood that the Urumqi East Second Ring Road (G216 Urumqi Transit Section Project) starts at the Shangshahe Interchange on the Turpan-Urumqi-Dahuangshan High-Grade Highway, connects with the Urumqi-Kuytun Expressway, and will cross Midong District, Shuimogou District, Tianshan District, and Shaya District. A total of 9 viaducts are set up along the entire line, among which the Midong Viaduct is the longest at about 3,175 meters.
　　The rotating bridge erection method is a bridge construction method that refers to using terrain or simple supports to prefabricate a half-span bridge structure at an appropriate position, then using the bridge structure itself as the rotating body to rotate on the bank pier or abutment and close at mid-span. It is mainly used in situations where supports cannot be installed, such as under rivers, railways, and expressways.