Danyang-Kunshan Grand Bridge: The World's Longest Bridge

The Danyang-Kunshan Grand Bridge is a 164.8-kilometer (102.4-mile) railway viaduct on the Beijing-Shanghai High-Speed Railway in eastern China, and it is the longest bridge in the world by a wide margin. Completed in 2010 and opened to traffic on June 30, 2011, it runs between the cities of Danyang and Kunshan in Jiangsu Province, carrying high-speed trains across the flat, water-laced lowlands of the Yangtze River Delta at speeds of up to 300 km/h.

No other bridge comes close to its length. The runner-up, the Changhua-Kaohsiung Viaduct in Taiwan, is roughly 157 km long, and most of the world's other "longest bridges" are also Chinese high-speed rail viaducts. To put 164.8 km in perspective, the Danyang-Kunshan bridge is longer than many entire countries are wide and dwarfs famous structures like the Golden Gate Bridge, which is barely more than 2.7 km including its approaches.

Why an Elevated Bridge Instead of a Ground-Level Track?

The most common question about the bridge is also the most revealing: why build 165 kilometers of viaduct across what is essentially flat ground? The answer lies in the unusual geography of the Yangtze River Delta. This is one of the flattest and most densely populated regions on Earth, where elevations rarely exceed 10 meters above sea level. The landscape is a dense patchwork of rice paddies, fish ponds, irrigation canals, rivers, villages, and lakes.

Building a straight, dead-level track on the ground would have meant filling in waterways, cutting across thousands of farm plots, and fighting constant flood and subsidence risks. By raising the line onto a continuous viaduct, engineers achieved several goals at once: they preserved scarce farmland beneath the structure, avoided disturbing the delta's intricate drainage patterns, kept the track above seasonal floodwaters, and—crucially—maintained the millimeter-level track geometry that high-speed trains demand. The elevated approach also lets roads, rivers, and canals pass freely underneath without level crossings.

Engineering and Design

• Type: Railway viaduct (continuous elevated bridge)
• Total Length: 164.8 kilometers
• Tracks: Two high-speed rail tracks
• Design Speed: Up to 300 km/h
• Opened: June 30, 2011

The bridge is not a single dramatic span but a vast assembly of thousands of nearly identical segments. The backbone of the design is the 32-meter prestressed concrete box girder, repeated again and again along the route and supported on concrete piers. This modular, repetitive approach turned bridge construction into something closer to a factory production line: girders could be cast in standardized molds, quality-checked, and installed in sequence at a rapid, predictable pace.

Where the route meets open water, the design changes. The bridge crosses roughly 9 kilometers of Yangcheng Lake, where longer spans and deeper, more robust foundations were needed to reach stable ground beneath the lakebed. Because eastern China sits in a seismically active zone, special anti-seismic bearings were installed along the structure to absorb ground movement and protect the track alignment. The continuous concrete viaduct also doubles as a noise barrier, shielding the communities it passes over from the sound of trains traveling at 300 km/h.

Geographic Setting

• Location: Jiangsu Province, eastern China
• Terrain: Yangtze River Delta lowlands
• Lake Crossing: 9 km across Yangcheng Lake
• Coordinates: 31.4°N, 120.8°E (approximate center)

The bridge threads through the heart of the Yangtze River Delta, the economic engine of modern China and home to tens of millions of people. The terrain it crosses is almost perfectly flat, which is exactly why the viaduct can run so straight and level for such an enormous distance. The route passes over countless minor rivers, canals, and ponds, but its signature water crossing is Yangcheng Lake, a shallow freshwater lake famous as the source of China's prized "hairy crabs," among the most expensive seafood delicacies in the country.

This delta environment is both an asset and a challenge. The flatness allows high-speed alignment, but the soft, water-saturated soils are prone to subsidence, and the region experiences seasonal flooding from monsoon rains and Yangtze River discharge. The elevated design sidesteps both problems, keeping the precision track infrastructure clear of unstable, waterlogged ground.

Construction History

• Construction Start: 2006
• Cost: ~¥30 billion (part of the ~$8.5 billion rail line)
• Workers: Up to 10,000 at peak
• Duration: About 4 years

The Danyang-Kunshan Grand Bridge was built as a single section of the larger Beijing-Shanghai High-Speed Railway, one of the most ambitious rail projects ever undertaken. Construction began in 2006 and proceeded simultaneously from many points along the 164.8-kilometer route, allowing different teams to work in parallel rather than building end to end.

Prefabricated box girders—some weighing as much as 900 tonnes—were cast at facilities along the corridor and carried into position by enormous launching gantries, machines specifically designed to lift, transport, and place each girder with precision. At the peak of work, crews were installing up to 30 girders per day across the various sections. This industrialized rhythm is what made it possible to complete the world's longest bridge in roughly four years. The entire Beijing-Shanghai line, including this viaduct, opened for service on June 30, 2011.

Cultural and Economic Impact

• Route: Beijing-Shanghai High-Speed Railway
• Travel Time: Cut the Beijing-Shanghai journey to about 4.5 hours
• Passengers: Hundreds of millions over its first decade
• Significance: A symbol of Chinese infrastructure ambition

The bridge is a critical link in the railway that connects China's two largest cities. Before high-speed rail, the Beijing-Shanghai trip took around 10 hours; today it can be done in roughly 4.5 hours, transforming a long overnight journey into a same-day business trip. This compression of travel time has knit the cities of the eastern seaboard into a single integrated economic zone, enabling commuting and commerce across hundreds of kilometers.

The Beijing-Shanghai line has carried hundreds of millions of passengers and ranks among the most profitable high-speed rail services in the world. Just as importantly, the elevated viaduct method pioneered at Danyang-Kunshan became the standard template for building high-speed rail across China's flat terrain, and the bridge endures as a showcase of the country's engineering capabilities.

Key Facts

• Length: 164.8 km, the longest bridge in the world
• Location: Danyang to Kunshan, Jiangsu Province, China
• Opened: June 30, 2011 (completed 2010)
• Function: Two-track high-speed rail viaduct, up to 300 km/h
• Water crossing: ~9 km over Yangcheng Lake
• Construction: Prefabricated 32 m box girders placed by launching gantries
• Workforce: Up to 10,000 workers; built in about four years

Fun Facts

• The bridge is longer than the distance from London to Brighton.
• Yangcheng Lake, which the bridge crosses, is famous for producing China's most expensive hairy crabs.
• If you drove the full length of the bridge at highway speed, it would take roughly an hour and a half.

Frequently Asked Questions

Where is the Danyang-Kunshan Grand Bridge located?

It is in Jiangsu Province in eastern China, running between the cities of Danyang and Kunshan across the Yangtze River Delta. Its approximate center sits near 31.4°N, 120.8°E, not far from Shanghai and Suzhou.

Why is the Danyang-Kunshan Grand Bridge so long?

It is a continuous elevated viaduct built to carry high-speed trains across flat, flood-prone, densely farmed delta land. Raising the track preserves farmland, avoids interfering with rivers and canals, keeps the line above seasonal floods, and maintains the precise, level geometry that high-speed rail requires—so the structure simply runs continuously for over 160 kilometers.

Is the Danyang-Kunshan Grand Bridge a road or a railway?

It is a railway viaduct, not a road bridge. It carries two tracks of the Beijing-Shanghai High-Speed Railway, with trains traveling at speeds of up to 300 km/h. There is no public roadway across it.

What is the second-longest bridge in the world?

The Changhua-Kaohsiung Viaduct in Taiwan, at roughly 157 km, is generally ranked second. In fact, most of the world's longest bridges are high-speed rail viaducts built in China and East Asia using similar elevated construction methods.