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The Qianximen Jialing River Bridge in Chongqing, China, has been shortlisted in the Highway or Railway Bridges category of The Structural Awards 2015. Here Dr. Man-Chung Tang and Dr. Delan Yin of T.Y. Lin International (China) Co, Ltd. discuss their work on the project.
With a population of 32 million, Chongqing is a rapidly expanding city. There are seven other bridges under construction there now, and a large number planned for the coming years, probably numbering in the hundreds. That’s because there are several big rivers in the city: Yangtze, Jialing, Wu, etc. and each requires a number of crossings. For example, out of 140 bridges over the Yangtze River now, 46 are in Chongqing alone. It’s no wonder the city is called the “Bridge Capital” of China!
Perhaps it’s this level of activity that makes structural engineers so well respected in China - as the Chinese proverb goes: "those who design and construct roads and bridges are accumulating their virtue".
The challenges for the design of the Qianximen Bridge were many: aesthetics were extremely important. The bridge is located at the mouth of the Jialing River, together with the Dongshuimen Bridge over the Yangtze, and together they form the gateway of the city - so it was really important that the two complemented each other visually. Also the river’s water level varies by up to 39 meters between low water and flood season, and we had to ensure that the bridge tower looked attractive in all river conditions. Most importantly, the bridge could not be too massive or it would disturb views of the city – hence the slender design of a cable-stayed girder bridge with a single cable plane. Indeed, the design is very Chinese, modelled on a traditional shuttle weave.
The engineering challenges were mainly around designing a structure that could carry both trains and traffic like cars and trucks, in a safe and cost-effective design.
There were other more practical considerations too. Timing was a major factor: we had to construct the foundation and lower portion of the towers and piers in one low water season, or we would have to wait for the next season the following year. Access was another crucial factor: Chongqing is a hilly city, the streets narrow and winding, and transportation of construction materials would be difficult – that meant we had to deliver most materials by river; but even that is difficult, as the width and depth of the river varies too much under different level of the water, making docking very problematic.
Every person who has seen this bridge has fallen in love with it. It is beautiful to look at, but especially enjoyable to those who walk across it on the pedestrian paths, which provide outstanding views over the city. We are very proud of this cost effective, significant and beautiful design.
Visit The Structural Awards 2015 website to learn more about the awards.