On September 11, phased technical verification was completed for the widening project of Nanzhong Bridge in the connecting section between the Guangdong Shiziyang Channel and the Guangzhou-Zhongshan-Jiangmen Expressway, and the project's first-item works passed acceptance. The project adopted a method that does not demolish the original bridge towers, does not replace the existing stay cables, and does not disturb the original foundations, implementing in-situ widening of the main girder of a long-span concrete cable-stayed bridge with a central cable plane. After renovation, the bridge will be widened from six lanes in both directions to eight lanes in both directions. Science and Technology Daily called it the world's first widening project for a long-span concrete cable-stayed bridge with a central cable plane.
Before construction, the project built a 1:1 full-scale test model, completed loading tests over eight months, and carried out nine research topics and thousands of simulation verifications focusing on structural cooperative force bearing, steel component anchoring, and connection between new and old structures. The project team ultimately adopted a lightweight steel structure splicing scheme, controlling the increase in the full-bridge dead load to within 2% and the increase in existing stay cable forces to within 4.7%, adding two lanes while retaining the original bridge's main load-bearing system.
In terms of construction equipment, the project independently developed eight C-shaped intelligent installation trolleys for high-altitude installation of steel components weighing more than 700 kilograms, enabling millimeter-level positioning; it also used 145 MPa high-pressure hydraulic cutting robots to perform remote-controlled cutting of existing concrete while preserving internal reinforcement. For transporting components inside the sealed box girder, a domestically pioneered in-box rail transport system was used to solve the problem of transferring and installing steel components in narrow, elongated spaces.
The connection between the new and old bridge bodies uses perforated steel plate connectors, namely PBL keys, to achieve force-bearing connection between the existing concrete structure and the newly added steel structure; the bridge deck pavement uses lightweight ultra-high performance concrete, whose structural self-weight is reduced by more than 15% compared with conventional schemes. Together, the above structures, equipment, and materials constitute the complete construction system for this bridge widening.
The Nanzhong Bridge widening project officially started closed construction on March 20, with a renovation period of about 300 days. The bridge is a key project in the connecting section between the Shiziyang Channel and the Guangzhou-Zhongshan-Jiangmen Expressway. The connecting section has a total length of 2,033 meters and, in addition to the Nanzhong Bridge widening, also includes the renovation of another bridge, the upgrade of the Fangma hub interchange, and the renovation of a 465-meter section of the western section of Guige Avenue in Nansha District.
The existing Nanzhong Bridge has six lanes in both directions, while the upper level of the Shiziyang Channel has eight lanes in both directions. This widening will add about 2.25 meters on each side of the bridge deck, ultimately forming eight lanes in both directions for Nanzhong Bridge and matching the lane scale of the upper level of the Shiziyang Channel. The entire connecting section is planned to open to traffic in 2027.