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Tsing Ma Bridge (青馬大橋) of Hong Kong is the world's fifth longest suspension bridge. It has two decks and carries both road and rail traffic. It has a main span of 1,377 metres (4,518 ft) (more than the famous Golden Gate Bridge in San Francisco) and a height of 206 metres (300 ft). The span is the largest of all bridges in the world carrying rail traffic.
The 40 m wide bridge deck has two carriageways on the upper level, each of three lanes, for road traffic, and the lower level contains two rail tracks and two protected emergency lanes for road traffic. There are also two sheltered carriageways on the lower deck for maintenance access and as backup for traffic when particularly severe typhoons strike in Hong Kong. Though the road traffic of the bridge had to be closed in that case, trains could still get through in either direction.
The Tsing Ma Bridge links Tsing Yi island on the east to Ma Wan island on the west. It is part of the Lantau Link, which, with three long span bridges links the New Territories and Chek Lap Kok, where the Hong Kong International Airport is located. The other two bridges are the Kap Shui Mun Bridge linking Ma Wan to Lantau Island, and the Ting Kau Bridge, linking Tsing Yi Island and Tuen Mun.
Tsing Ma Bridge by day (October 2004) The rail line is part of MTR's Tung Chung Line and Airport Express.
Construction work of the bridge began in May 1992 and ended in May 1997. It cost HK$7.2 billion. The Lantau Link, of which the bridge is an integral part, was opened on April 27, 1997. The ceremony was inaugurated by the former British Prime Minister Margaret Thatcher.
Surveillance cameras were installed over the bridge to record traffic conditions. The video is available at the government website[[1] (http://traffic.td.gov.hk/snapshots/big5/li/frame_020104.asp)]. It is updated every two seconds.
The Tsing Ma Bridge has been an important gateway to Lantau. It will become part of the planned Route 8 expressway, which will connect the Lantau Link, the West Kowloon expressway, Cheung Sha Wan and Shatin.
Design
The bridge is a joint venture between American and Japanese Construction companies. Trafalgar House Construction (Asia) Limited, Costain Civil Engineering Limited of Britain, and Mitsui and Co. Limited of Japan were the major contractors. Mott MacDonald Hong Kong Limited was further contracted to design and engineer the bridge.
Since it is the main component of the Lantau Link and the only vehicular exit and entrance to Hong Kong International Airport, the closure of road traffic and trains will cause visitors great inconvenience. Therefore, the bridge is designed to stand windspeeds at a maximum of 290 km/h. The bridge has high navigational clearance to Hong Kong Harbour. For safety reasons, it has to be closed during strong typhoons. An example of this would be at the time Typhoon Victor, then classfied as signal no. 8 typhoon, hit Hong Kong in August 1997. That was the first and only time the bridge has been closed. In some other cases, if there is bad weather that is not as severe, the upper deck of the bridge will be closed as well. For instance, in September, 1999, owing to inclement weather, the upper deck of the bridge was closed and motorists were advised to use the lower deck which remained open to traffic.
Five major components in its construction
- Foundations and the construction of the bridge tower - one tower located on Tsing Yi side and the other on a man-made island 120 m from the coast of Ma Wan Island. Both towers are 206m above sea level and founded on relatively shallow bedrock. The towers are two-legged with trusses at intervals, in the form of portal beam design. The legs were constructed with high-strength concrete of 100 MPa strength, using a slipform system in a continuous operation.
- Anchorages - the pulling forces in the main suspension cables is taken up by large gravity anchorages located at both ends of the bridge. They are massive concrete structures deeply seated on bedrock on the landside of Tsing Yi and Ma Wan island. The total weight of concrete used in the two anchorages is about 300,000 tonnes.
- Main cables - The cables were constructed by an aerial spinning process. The process involved drawing wires from a constant-tension supply, and pulling loops of these wires from one anchorage to the other, passing a 500-tonne cast-iron saddle on top of each bridge tower seating the cable. A total of 70,000 galvanised wires of 5.38 mm diameter were placed and adjusted to form the 1.1 m diameter main cable.
- Suspended deck - The steelwork for the deck structure was fabricated in Britain and Japan. After delivery, they were further processed and assembled in Dongguan of China into standard deck modules. A total of 96 modules, each 18 m long and about 480 tonnes in weight, were prepared. These deck modules were brought to the site by specially designed barges and raised into the deck position by a pair of strand jack gantries that could manoeuvre along the main cable.
- Approach span on Tsing Yi side - similar in form and cross-section to the suspended deck, but the approach span was supported on piers instead of cable-support. The first span was assembled on the ground and raised into position using strand jacks. Further erection then proceeded in cantilever in smaller sections, using derrick cranes stationed on the deck level. An expansion joint which allowed for a maximum thermal movement of 850 mm was also provided and located inside the approach span section.
The wind tunnel
The objectives of the wind tunnel studies were to demonstrate the safety of the structure
under construction and once completed, both with respect to aerodynamic stability as well as the possible effects of extreme typhoon wind speeds. A further objective was to provide
dynamic response data at several key locations to compare with full scale data from the ongoing
monitoring programme, conducted by the Highways Department of Hong Kong.
It is a 1 to 80 scale section model of the deck in the erection stage and 1 to 400 scale full aeroelastic model of the entire bridge. It is a Monte-Carlo simulation of the typhoon wind climate. The full model was tested in different stages of construction in turbulent boundary layer flow, complete with the local topography in order to model the wind conditions at the site. The model tests identified critical stages of erection that allowed the construction schedule of the bridge to be tailored to avoid the typhoon season. The comparison of model test results and the full scale monitoring will assist engineers to better understand the behaviour of long span bridges in wind and to improve current design methods.
As a tourist sight
Tsing Ma Bridge becomes a favourite scenic spot as well as a famous landmark. In order to watch and get further information about it, one can go to the Lantau Link View Point which is located at the northwest corner of Tsing Yi Island. It consists of Tsing Yi Trunkroute Viewing Terrace and the Visiting Guest Centre. The model, pictures and the structure of the Tsing Yu trunkroute are on display at the Centre. The View Point is opened from 10:00 am to 5:00 pm on weekdays; from 10:00 am to 6:30 pm on Saturdays, Sundays and public holidays. It is reachable only by a bus running on holidays (route 243R), taxi, or private car. Parking is prohibited on this gigantic Bridge. From the Scenery Viewing Terrace, one can also see the Ting Kau Bridge and Kap Shui Man Bridge. They are the other two bridges listed in the world's "Three Mosts" as well.
Ways to get there
To the bridge
Take the MTR to Tsing Yi and get a taxi or all airport buses which cross Tsing Ma and Kap Shui Mun bridges. There is a green minibus 309M running between the Tsing Yi Airport Railway station and the Lantau Link Visitors' Centre every Saturday, Sunday and public holidays. The service departs from the Tsing Yi station operating between 9:30 am and 5 pm and that departs from the Visitor's Link operating between 10 am and 6:30 pm. The minibuses run every 60 minutes and cost HK$7 for a single journey.
To the view point
(From Kwai Fong MTR station) There is a shuttle bus on the passage beside the Metroplaza and Kwai Tsing Theatre on holidays. It departs from 10:00 am to 4:00 pm; and returns from 10:30 am to 5:30 pm. It operates at an interval of one hour.
(From Tsing Yi MTR station) A shuttle bus is also available outside Maritime Square on holidays. It departs from 10:30 am to 4:30 pm; and returns from 11:00 am to 6:00 pm. It operates at an interval of one hour.
Operating hours of architectural lighting
At night, there is an architectural lighting which makes the bridge even more gorgeous. The operating hours are as follows:
Monday to Sunday:
6:00 p.m. to 12:00 midnight (October February) and 7:30 p.m. to 12:00 midnight (March September)
Special Event:
6:00 p.m. to 1:00 a.m. of the following day (October February) and 7:30 p.m. to 1:00 a.m. of the following day (March September)
Toll & Fee
The double tolls for motor cycle, private car, public double-decked bus and heavy goods vehicle are HK$20, $30, $60 and $80 respectively.
Traffic speeds
There are speed restrictions on the bridge. Traffic speeds are 80 km/h for automobiles and 135 km/h for trains.
See also
External Links
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