Lancanjiang River Railway Bridge
Lancanjiang River Railway Bridge
890 feet high / 271 meters high
1,122 foot span / 342 meter span
Due for completion in 2013, the stunning Lancanjiang Railway Bridge is the centerpiece of a new line between the cities of Baoshan and Dali in western Yunnan Province. The new railway bridge crosses the upper reaches of a reservoir that was formed behind Xiaowan, the 2nd highest concrete dam in the world. The spectacular 958 foot (292 mtr) high double curvature structure holds back a body of water some 787 feet (240 meters) deep along the Mekong (Lancang Jiang), a river with several of the largest and highest hydroelectric dams in the world including the Manwan, Dachaoshan, Nuozhadu and Jinghong. The Mekong River is the only international river in Asia linking 6 countries. The river has more species of fish than any other waterway on earth except for the Amazon. The full reservoir is 164 feet (50 meters) deep beneath the new railway bridge.
Instead of using cable stays and tiebacks to build the arch, the two steel truss arch halves were built vertically on either side of the canyon slopes on top of scaffolding. While still in a vertical position, the two halves were then rotated at the arch springing and then lowered down over the gorge where they were connected at the crown. A highline was then used to build the vertical spandrel supports and road deck. The total length of the bridge is 698 meters.
As with most of China's steel arches, the Lancanjiang arch is known as a CFST or concrete filled steel tube. Once the steel arch pieces were connected at the crown, concrete was pumped inside of the hollow main ribs from the foundations upward to the crown. First used by the Chinese in 1990, they have refined and improved the technique and now use it on the majority of their steel arch bridges. Depending on the length of the span and the width of the bridge, different styles of tubing are used. The advantage is the ease of erecting and moving the light, thin-walled steel tube sections into place. Once the concrete is pumped into the tubes and solidifies, the entire structure becomes very stiff with great compressive strength.
The location has become a showcase for 3 high spans including an older suspension bridge, the new railway bridge and an even higher pipeline suspension bridge that is the 2nd highest of its type in the world after the Hegigio Gorge Pipeline Bridge in Papua New Guinea.
Lancanjiang Railway Bridge construction site. The two halves of the arch are beginning to rise vertically along either slope.
An early construction view before the arch foundation was complete.
The temporary suspension bridge built for access to either side of the gorge. The Xiowan Dam reservoir has not reached the bridge site.
The highlines and part of a completed arch half on the opposite canyon wall.
Construction elevation showing the arch halves that are constructed on scaffolding on the slopes before being positioned vertically and then lowered out over the gorge and connected at the crown.
The location will eventually be the home to 3 high bridges including the suspension road access bridge, the railway arch and the pipeline suspension bridge.
The massive Xiaowan Dam that is now the second highest concrete dam on earth after the under construction Jinping Dam.
Xiaowan Dam during the final stages of construction.
The completed dam with nearly a full reservoir behind it. The water depth is approximately 787 feet (240 meters) just behind the dam.
The water level has not yet reached the full pool height of 1,225 meters though the water can be allowed to go as high as 1,240 meters during floods.