Hangzhou bay bridge

          The Hangzhou Bay Bridge is a cable stayed bridge in China. Located on the Hangzhou Bay and crossing the Qiantang River and the Yangtze River Delta, it is the longest ocean crossing bridge in the world. Preparatory work and designing of the bridge started in 1994, and construction started in 2003. Construction finished in 2007, but the bridge was not officially open to the public until 2008. The bridge itself cuts transportation time from Ningbo to Shanghai down to two and a half hours, when it would normally take four hours. The estimated total cost for the project is almost $1.5 billion.

          There were several design constraints when this bridge was designed. Over 700 different experts from all over the world were involved in many technical studies to ensure the safety and reliability of the bridge. Since it mostly crosses the ocean, it couldn’t be completely assembled on location. The majority of the bridge was built in small pieces on land, and then the pieces were brought to the location of the bridge and assembled. Since this bridge is so long, spanning 5.2 kilometers, it is very important to prevent bridge collapse. A cable stayed bridge was the best bridge design to use. The area that the bridge sits in is also prone to typhoons, so that had to be taken under consideration as well. All of these factors together are why this bridge took so long to design.