The Kap Shui Mun Bridge (KSMB) in Hong Kong is one of the longest cable-stayed bridges in the world that transports both road and railway traffic, with the upper deck used for motor vehicles and the lower deck used for both vehicles and the MTR. It has a main span of 430 metres (1,410 ft) and an overall length of 750 metres (2,460 ft). It spans the Kap Shui Mun marine channel between Ma Wan and Lantau and has a vertical clearance of 47 metres (154 ft) above sea level. The bridge was completed in 1997.
The total length of the Kap Shui Mun Bridge includes a 70-metre (230 ft) approach span on the Lantau side. There is a column in each of the back spans of the cable stayed bridge, making four 80-metre (260 ft) spans, adding to the 430-metre (1,410 ft) main span. This makes the total length 820 metres (2,690 ft). The 503-metre (1,650 ft) Ma Wan Viaduct was constructed under the same contract as the KSMB. The viaduct connects the KSMB to the Tsing Ma Bridge, forming the Lantau Link, which was built to provide access to the new airport. The navigation clearance of 47 metres (154 ft) is part of the reason that the H-shaped towers are 150 metres (490 ft) tall.
The Kap Shui Mun Bridge is not symmetrical, in that the 160-metre (520 ft) back span length (2 80-metre (260 ft) spans) is less than half of the main span length (which would be 215 metres (705 ft)). To provide the balance that symmetry will normally provide, part of the bridge has a composite structure. The center 387 metres (1,270 ft) of the main span uses a steel-concrete composite to make the structure lighter. The back spans and the rest of the main span are concrete. Using the lighter steel cross section in the majority of the main span serves to equalize the horizontal forces on the towers and balance the bridge.
Because the lower deck carries both rail and traffic, the cross section is designed as a Vierendeel truss. This means that there are no diagonal members in the cross section and that vehicles and rail cars drive through the openings provided by the Vierendiel design.