A new Chinese suspension bridge, set to open November 25, has won top honors for being such a long three-tower/two span bridge.
When it opens on Nov. 25, Taizhou Bridge will carry six lanes of traffic (plus two maintenance lanes) nearly 3-km across the Yangtze River. Though the total length of 2,940 m is an awfully long way, the bridge has two main spans using three towers rather than the norm of one main span using two support towers.
The two spans are each 1,080 m (3,540 ft) long, which individually is less than the main span of the Golden Gate Bridge at 1,280 m (4,200 ft), and much less than the 1,990-m (12,830 ft) span of the Akashi Kaikyō Bridge, the longest main span of any suspension bridge on Earth. Two end spans of 390 m (1,280 ft) connect Taizhou Bridge with the banks of the river.
But in using two spans the Taizhou Bridge is a major breakthrough in structural engineering. The design requires the perfect balance of flexibility and rigidity in its 192-m (630-ft) steel central tower in order to withstand changing and imbalanced loads to either side. The complementary side towers are 178 m (584 ft) tall, and are made of concrete. The two main cables supporting the bridge are 3,110 m (10,200 ft) long and 72 cm (28 in) in diameter.
Think about it. The central tower is going to be pulled from both directions. Similarly, the outside towers must have incredible strain pulling them towards the center. Balancing it all is an amazing architectural achievement.