Suspension bridges make cities work, as evidenced by the earliest structures built in China over 2,000 years ago to speed up the pace of life and commerce across the water. It’s not surprising, then, that modern China’s sizzling economic growth coincides with the construction in the last decade of three of the world’s biggest bridges, helping the country span the gap with the world’s major economies.
The Runyang South Bridge, with a span of 1,490 meters (4,888 feet), was completed two years ago. It crosses Asia’s largest river, the Yangtze, and is China’s latest effort to speed the movement of people and products across water.
Jiangyin Bridge, in Jiangyin, China, also crosses the Yangtze River with a span of 1,385 meters (4,543 feet)to connect the cities of Jiangyin and Jingjiang. Originally, completion was expected to commemorate the 50th anniversary of the Chinese Revolution in 1997. It missed by two years, but still gave the country its largest bridge from 1999 to 2005, until the Runyang South surpassed it.
Completed in 1997, Hong Kong’s 1,377-meter (4,518-foot) Tsing Ma Bridge was named after Hong Kong Islands Tsing Yi and Ma Wan. Its main claim to fame: It’s the longest span for rail traffic in the world. The bridge also has five lanes for trucks and cars, two of which are reserved for emergencies.
But the king of suspension bridges remains the 1,991-meter (6,529-foot) Akashi-Kaikyo in Kobe-Naruto, Japan. More than 23% longer than the runner-up, the bridge replaced ferries that made the run from Kobe to Iwaya. The width of Akashi Strait, an international shipping lane, required that the Akashi-Kaikyo be at least 1,500 meters wide.
Denmark’s Great Belt Bridge is No. 2 at 1,624 meters (5,328 feet). It rendered ferry service between the islands of Zealand and Funen obsolete when it was completed in 1998. The largest construction project in Denmark’s history, it reduced an arduous ferry journey to a 10-minute drive.
The first suspension bridges date back to 206 B.C., when the Chinese used vines to carry loads over water. Eventually, vines were replaced by plaited bamboo, and finally, metal. During the late 1800s, the modern version of the suspension bridge developed in both the United States and Britain.
Engineer John Augustus Roebling created the model still used today. His most famous structure, New York’s Brooklyn Bridge, became the icon of suspension bridges, with a center span of 486 meters (1,595 feet). Completed in 1883, the Brooklyn Bridge was the first to use the steel cables that eventually became the standard for suspension bridges.
A marvel of its time, the Brooklyn Bridge is quaint by today’s standards. The length is barely a quarter of the $3.6 billion Akashi-Kaikyo. The price tag dwarfs that of many major bridges around the world. For example, the 1936 construction of the San Francisco-Oakland Bay Bridge, still one of the marquee structures in the U.S., cost $1.75 billion in today’s dollars.
That’s not only a reflection of the newer Akashi-Kaikyo’s larger size, but also of the extra trusses and technological advances that provide superior dimensional stability that stand up against strong winds and other weather factors.
This technology is necessary as the need to move goods faster accelerates with the demand for cost-savings created by not having to transfer loads from truck or rail to boat and back again. Just-in-time inventory doesn’t happen without infrastructure investment.
There’s also the simple matter of civic pride and image. A bridge’s economic value of direct transit is augmented by the symbolism of grace and glamour that decorate a city’s image. Nothing says “raw power” like a major bridge dotting the city skyline.
China, for its part, isn’t finished building. A pair of suspension bridges now under construction there include the Xihoumen Zhoushan Island Bridge (1,650-meter center span) and the Yangluo Bridge (1,280 meters), both of which stand to break onto the list of the world’s top 10 once they’re completed.