Anji Bridge (605AD) Zhaoxian, Shijiazhuang, Hebei, China
The Anji Bridge, also known as Zhaozhou Bridge, in the Hebei Province of China is that country’s oldest still standing bridge. Crossing the Xiao River it is also the world’s oldest open-spandrel arch bridge.
Designed and constructed during the Sui Dynasty the bridge is 51 m (167 ft) long with a central span of 37m (122 ft). It rises 7.3m (24 ft) above the river and is 3m (10 ft) wide. It was constructed using 28 slim, curved limestone slabs, joined with iron dovetails to allow the arch to adjust to shifting in the supporting abutments and to prevent collapsing even if a segment of the arch breaks.
At each end smaller arches transmit the load of the deck down to the main arch thereby reducing the total weight of the bridge. In times of flooding the open spandrels allow water to flow through which alleviates the stress on the bridge structure. This is colourfully described on an inscription commemorating the bridge’s designer Li Chun as “The four small arches inserted, on either side two, break the anger of the roaring floods, and protect the bridge mightily.” The inscription concludes: “Such a master-work could never have been achieved if this man had not applied his genius to the building of a work which would last for centuries to come.”
Construction began in 595 AD and was completed ten years later. The Anji Bridge, which literally means “Safe Crossing Bridge” has remained intact through many wars, floods and earthquakes and is still in use today. The only major changes over the years were the periodic replacement of the balustrades.