What changed
China has completed Pier 9 of the Nanxi River Bridge on the Wenshan–Mengzi railway in Yunnan, the first reported use of a lattice-pier structure in Chinese railway construction. The steel-tube concrete pier stands 105 metres high; its lattice section was assembled from seven segments and 176 prefabricated components, with the heaviest weighing 24 tonnes.
The bridge is 789.71 metres long, with the track as much as 118 metres above the ground. Its three lattice piers are being built across steep terrain marked by rockfall hazards and karst geology.
Why it matters
The design tackles a very physical problem: how to hold up a railway in deep, unstable mountain country without filling the entire structure with conventional materials. The pier is wider at the bottom and narrower at the top, using steel tubes and H-beams around a high-strength concrete core.
Project officials say the approach could cut concrete and steel use by 30% to 50%. That figure is a project claim, not an independently verified result, but the construction method itself is significant. Prefabricated parts can be assembled away from the most difficult work areas, while precision surveying and dynamic adjustments are used to keep the pieces aligned to millimetre-level tolerances high above the valley.
The broader test is whether this remains a one-bridge solution or becomes a repeatable railway method. The 116-kilometre Wenshan–Mengzi line is designed for 160 km/h operation as an electrified, double-track passenger-and-freight railway. If the lattice-pier techniques prove durable in service, they could give future mountain rail projects a standard design for crossing terrain where ordinary high piers are costly and difficult to build.
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