AN ULTRA slim bridge deck was the key element which last week won the design competition for Hong Kong's new Tsing Lung suspension bridge project.
Maunsell Hong Kong will produce detailed designs for the $1.08bn structure, for which construction will begin in 2002. Tsing Lung will be the world's third-longest span when completed in 2007.
The design's so-called Generation Three deck structure could halve the depth of the steel box deck on the 1,418m main span to about 2.5m, crucially reducing deck weight.
Hong Kong Highways Department engineer and design competition committee chairman John Chai told NCEI:
'That could be critical for the bridge because of severe constraints on its height. The bridge will have a span-tosag ratio of one to 15 compared to a normal one to ten.'
The Hong Kong Highways Department is competition sponsor and the client for the project. Very short main towers are required because the bridge lies on the flight path out of the new Hong Kong International airport on the north side of Lantau island. The bridge will connect Hong Kong's second biggest island to the New Territories across the busy Ma Wan shipping channel.
Meanwhile, the Highway Department also this week announced 22 firststage proposals from 16 consultant groups for the 1,000m span bridge across the entrance to the Kwai Chung container ports.
The department believes a cable stay for the Stonecutters Bridge would make the best solution even though this would push technology beyond the 890m span limit so far achieved in Japan.