On June 26, the box girder of the closure segment of the Shangjin Zuojiang double-track grand bridge — a control engineering project on the Chongzuo–Pingxiang section of the Nanning–Pingxiang high-speed railway in Guangxi (the Nanning–Pingxiang HSR Chongzuo–Pingxiang section) — completed concrete pouring, marking the successful closure of the **only low-pylon cable-stayed bridge on the entire line. With this, the major key works along the whole Chongzuo–Pingxiang section of the Nanning–Pingxiang HSR are basically complete, opening up the track-laying and girder-erection corridor for the whole line and laying the foundation for track-laying work in September this year.

In the early hours of that day, nearly 20 construction workers coordinated with each other, operating concrete pump pipes and vibrators to carry out concrete pouring for the closure segment of the Shangjin Zuojiang double-track grand bridge. After three hours of continuous work, 36.7 cubic meters of concrete were poured and the bridge was successfully closed.

Photo shows construction workers carrying out concrete pouring.

"Concrete has a thermal contraction effect, and pouring is most effective during the period of lowest temperature in the early morning, which allows the continuous girders on both sides of the closure segment to be joined more firmly into a whole," said Jiang Jie, on-site manager of the Shangjin Zuojiang double-track grand bridge of the Chongzuo–Pingxiang railway under China Railway Shanghai Engineering Group.

Construction of the Shangjin Zuojiang double-track grand bridge began in July 2022. Located in Longzhou County, Chongzuo City, Guangxi, the bridge has a total length of 2,130.8 meters. Its main bridge is a low-pylon cable-stayed bridge spanning the Zuojiang River and the Zuojiang National Wetland Park, adopting a rigid-frame continuous girder composite structural system. The pylons take a double-column form, with the main pylon 35.3 meters high and nine pairs of stay cables arranged on each side of the bridge. The lower part of the bridge contains numerous karst caves, and tower column construction involves working at heights of up to 65 meters, classified as super-grade high-altitude work. Cable saddles must be embedded in the tower columns, entailing high construction risk, strict technical requirements and demanding environmental and water-conservation standards.

To advance the project safely and efficiently, the contractor China Railway Shanghai Engineering Group, under the guidance of Guangxi Nanchong Railway Company and the Nanning Railway Engineering Construction Command, strictly followed premium project management standards, continuously optimized construction plans, strengthened on-site control, and carried out targeted research on key technologies. Taking technological leadership as the breakthrough point, it adopted hydraulic climbing formwork together with a stiff skeleton for the main pylons of the cable-stayed bridge and cantilever casting for the girder section, and applied the "four new" technologies — new equipment, new methods, new techniques and new materials — successfully achieving large-span river crossing construction and ensuring safe, high-quality construction.

Construction technicians check the construction plan on site.

During construction, China Railway Shanghai Engineering Group ensured edge protection and enclosures, and installed catch nets beneath the form travelers and traveling equipment on both sides of the bridge to ensure that construction materials and waste did not enter the Zuojiang River or the wetland park, meeting environmental protection requirements.

With the successful closure of the Shangjin Zuojiang double-track grand bridge, all seven major key works — tunnels and bridges — along the Chongzuo–Pingxiang section of the Nanning–Pingxiang HSR have been holed through or closed. To date, all tunnels on the section have been holed through, the subgrade and bridge works have been completed at 98.36% and 96.73% of the designed total respectively, and construction of station buildings has been fully launched.

"At present, construction workers at 125 work sites along the entire line are pressing ahead with the project. It is expected that 'four-electric' (communication, signal, power and electrification) construction can begin in early July this year, and track-laying in September. The whole line is expected to open to traffic next year, when the rail travel time from Nanning to Pingxiang will be shortened from more than four hours to just over one hour," said Tang Xiaolin, commander of the Chongzuo on-site command of the Nanning Railway Engineering Construction Command under China Railway Nanning Group Co., Ltd.

The Chongzuo–Pingxiang section of the Nanning–Pingxiang HSR is 81 kilometers long with a design speed of 250 kilometers per hour. Three new stations — Ningming East, Longzhou and Pingxiang East — will be built, and the line reserves the conditions for future extension to Vietnam. The Nanning–Chongzuo section of the Nanning–Pingxiang HSR opened to traffic in December 2022. Once the Chongzuo–Pingxiang section is completed and opened, the entire Nanning–Pingxiang high-speed railway will be connected, forming an important international transport corridor between China and ASEAN. This is of great significance for building an important economic corridor between China and ASEAN countries and turning Guangxi into an important gateway for the organic alignment of the Belt and Road Initiative.