World's longest sea crossing starts
By Richard High16 December 2009
Construction of the world's longest sea crossing has started, just 18 months after completion of the previous record holder, the Hangzhou Bay Bridge.
The 50 km-long, Y-shaped crossing will link Hong Kong-Zhuhai-Macau with a 35 km bridge and a 5.5 km-long tunnel, according to state news agency Xinhua.
Due to be completed by 2015, the CNY 73 billion (US$ 10.7 billion) construction costs will be shared by the authorities in all three territories.
Work has now started on land reclamation to create a 216 ha artificial island close to Zhuhai that will be the customs checkpoint for the crossing.
Much of the structure will be prefabricated in order to meet the completion deadline of 2015.
Offsite fabrication will include precast columns and precast concrete box sections for the decks, while the tunnel will be made of 100 m-long precast concrete segments with assembly on site.
First proposed in 1983 as a way of fostering economic ties between China, Hong Kong and Macau the bridge is expected to generate HK$ 45 billion (US$ 5.8 billion) of "economic benefits" within the first 20 years of use, according to Xinhua.
The bridge crosses three navigation channels, while the tunnel goes under a fourth to avoid the flight path of a nearby airport.
The design, which includes 170 m-high piers, is such that it will minimise the bridges' impact on estuary flows by limiting the size and number of columns in the water said Xinhua.
However, environmental groups, including the World Wildlife Fund (WWF), have warned construction could devastate the estuary's marine ecosystems and endanger the rare Chinese white dolphin.
The Hangzhou Bay Bridge, a cable-stayed bridge across Hangzhou Bay, eastern China is 36 km long with six expressway lanes in each direction, making it the second-longest bridge in the world after the 38.6 km-long Lake Pontchartrain Causeway in Louisiana, US.
Construction of the CNY 11.8 billion (US$ 1.5 billion) S-shaped bridge started in 2003 and finished in 2007. The bridge has two main spans, a 448 m northern span, and a 318 m southern span.