By Tan Xingyu

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Bridging the World

By Tan Xingyu

New high technologies were applied in the construction of Longjiang Grand Bridge

Tengchong， a rural town in southwestern China's Yunnan Province， is located on the only path from Kunming，Yunnan's capital， to Myanmar， which borders Yunnan. However， the eight-hour Kunming-Tengchong journey has never been much of a joy to travelers， as the rugged， mountainous route makes for a slow and bumpy ride.

However， the opening of Longjiang Grand Bridge along this route has made that rugged，joyless journey a thing of the past. The bridge，which officially opened to traffic on April 20，is the longest bridge in Asia， and represents a positive step in improving regional transportation links between Yunnan Province and Myanmar.

The Longjiang Grand Bridge appears similar to the Golden Gate Bridge in the United States as both are suspension bridges with double towers. Designed for a speed of 80 km/ hr traffic， it features a four-lane highway with traffic flowing two lanes in each direction.

As Yunnan sees much precipitation throughout the year in a fairly damp and humid climate， fog oThen enshrouds the bridge. Prior to the bridge's construction， passage from Baoshan，the city closest to the bridge， to Tengchong involved a 13.5 km detour through nearby mountains to bypass the Longjiang River， significantly lengthening the trip. Now， however， the driving distance required to reach Tengchong is only 2.4 kilometers.

Record Maker

The 2，471-meter-long bridge， with a main span of 1，196 meters， towers 280 meters abovea valley， through which the Longjiang River snakes. It is considered Asia's largest suspension bridge as well as the continent's highest valley bridge， with the world's longest valley span.

Beginning construction in August 2011， workers and engineers were forced to overcome various challenges posed by such elements as a long rainy season， complicated geology， advanced construction requirements and transportation difficulties. The construction of the bridge required the development of five new technologies never seen before in bridge projects.

Considering the complexity of the seismic zone in which the bridge is located， the construction of the bridge remained doubtful to many engineers. Critics pointed to sideslope stability as well as the region's complex geological structure. Therefore， the application of various advanced technologies was required during construction.

Despite these difficulties， it only took six months for the construction team to dig out 700，000 cubic meters of clay for the bridge's foundation and seven months to pour 110，000 cubic meters of concrete to fill in the foundation. It took only 43 days to build the bridge's main system of cables， breaking a world record in suspension bridge construction.

On December 12， 2012， engineers flew a drone carrying the two-millimeter transition rope crucial to connecting the two sides of the bridge together， marking the end of construction of the lower parts of the bridge and the beginning of the construction of the upper structure.

Due to complex topography and unpredictable gusts of wind， connecting the rope from one end of the bridge to the other proved difficult. Helicopters， ships and even a rocket were quickly ruled out due to concerns in both safety and feasibility. Because it doesn't require a pilot to actually sit in the craft itself， a drone was deemed ideal. This marked the first time in the history of Chinese bridge construction that an aircraft was used to carry a bridge's transition rope. It was one of many breakthroughs in a project that presented engineers and construction crews with a multitude of challenges they had never encountered before.

Infrastructure

The world's longest bridges

Of the world's 10 longest bridges， seven are in China

China's Bridge Projects on the World Stage

Today， a large number of the world's most ambitious infrastructure projects have been completed in China. Among those are the world's largest bridge， its largest airport and its longest natural gas pipeline.

From a historical perspective， that is nothing new. China has a long history of completing huge infrastructure projects. The Great Wall and the Grand Canal， two of the country's most famous landmarks， were constructed thousands of years ago. Completion of such projects requires the most advanced technology of the time. Once again， Chinese technologies are at the forefront of infrastructure projects across the globe.

China began industrializing in the mid-1950s. To date， it has grown into one of the world's most technologically advanced countries. Nowadays， China is known for its project quality， particularly in equipment， hydraulics， roads and bridges， as well as in civil architecture.

Bridge construction represents an integration of the manufacturing and materials industries. There's a saying in the bridge-building industry that the United States was the elite of the 1970s， Japan was the elite of the 1990s and China has been the elite since 2000. What makes China elite today？Most significantly， Chinese bridges span the longest distances. The longer the bridge， the more advanced the technology required.

There are currently 28 suspension bridges in the world that span more than 1，000 meters，and 11 of them are in China. There are currently 11 such bridges under construction， and nine of those are in China. Moreover， China is home to 17 of the 21 cable-stayed bridges in the world which span more than 600 meters，nine of the 12 with a span of more than 420 meters， and 12 of the 20 concrete bridges with a span of more than 250 meters. FiTheen of the 21 highest bridges in the world can also be found in China. The Longjiang Bridge is the world's 22nd highest.

Over the past decade， China's bridge-building industry has grown globally. Chinese bridge-building firms control 50 percent of the global market， and have worked on or are currently working on various international projects including the Second Penang Bridge in Malaysia， the Atlantic Bridge in Panama， the Second Incheon Bridge in South Korea， the San Francisco-Oakland Bay Bridge in the United States and even China's own Hong Kong-Zhuhai-Macao Bridge.