John Metcalfe was CityLab’s Bay Area bureau chief, covering climate change and the science of cities.
In the realm of tall bridges, Aizhai takes first place as the world's longest.
Folks who have trouble driving over the Golden Gate or New York's George Washington Bridge should probably just close this window now. The Aizhai Bridge in Hunan Province is so high and so long that a car careening off the side would take an excruciating 8 seconds to hit the earth, where presumably it would drive itself several feet deep like a bunker-buster.
Aizhai is located 20 minutes outside Jishou, a city of nearly 300,000 people whose history stretches back 2,000-plus years. The steep, curvy mountain roads have given the area's citizenry a traffic headache for as long as cars have existed – perhaps longer, in the case of pack-mule gridlock. This bridge, which opened to traffic last month after 5 years of construction, is meant to ease congestion by laying six lanes of Baotou–Maoming Expressway over the Dehang canyon. What was once a 4-hour slog between Jishou and Chadong is now a 1-hour trip, albeit one over a yawning abyss that would love nothing more than to swallow a careless driver.
In the weird subset of the population utterly fascinated by bridges, Aizhai is the equivalent of an albino whale: rare, impressive and just asking for a good ride. The structure is 1,102 feet high (or 1,150, as reports differ) and 3,858 feet long, making it the tallest tunnel-to-tunnel bridge in existence. Aizhai also has the longest span in the realm of super-high bridges, according to this loving write-up in Highest Bridges. The people who helped build it assign it some other firsts, too, though I'm not enough of an engineer to figure out how impressive they are. Here's what's posted on the website of the Hunanese government:
Hunan Road & Bridge Construction Group, together with other partners involved in the bridge construction, created four "No.1 in the world": the first is the 1,176 m long main span; the second is the first application of pylon and girder separation structure; the third is the first use of rock anchor suspension and carbon fiber as the pre-stressed reinforcement material; and the fourth is the first adoption of rail cable sliding technique to erect steel truss girder.
The world's longest bridge is still the Akashi Kaikyō in southern Japan (6,532 feet long), but Aizhai carries a supreme WTF quality that makes it outshine the competition. The towering steel structure just doesn't seem to belong in the bucolic landscape. Residents down below must live in a state of heightened awareness that a chunk of gravel or tossed-out litter might plummet off the span and aerate them. Take a look at this monster:
Top photo by China Daily Information Corp./Reuters, bottom ones by inveterate bridge photographer Glabb.