New land link an engineering feat

October 20, 2018

The Hong Kong-Zhuhai-Macao Bridge, which will open to traffic on October 24, will be the world’s longest bridge and tunnel sea crossing, after its project team embraced numerous engineering challenges.


The new 55km land link stretches from Hong Kong with the 12km Hong Kong Link Road and the 30km Main Bridge spanning across the Lingding Channel and Tonggu Navigation Channel to Zhuhai and Macao Ports, followed by a 13km Zhuhai Link Road.


Highways Department Engineer Caryl Poon said the construction of the dual three-lane Hong Kong Link Road, made up of a 9.4km viaduct and 1km tunnel, had posed a number of challenges to the project team.


She said the link road is close to the Hong Kong International Airport, meaning its construction has to comply with the Airport Authority’s stringent aviation safety requirements.


As it also stretches over a fairway west of the airport island, a 41m vertical clearance above sea level is required for the viaduct section.


To save construction time and reduce impact on marine traffic and the environment, Ms Poon said precast concrete units were deployed.


“We actually use very, very large precast pile cap (shells) as well as piers. All these bridge segments here, it’s over 5,700 units of them and each of them weighs 75 to 225 tonnes. That is actually equivalent to (the weight of) three to nine double-deck buses.”


For the Scenic Hill Tunnel, the construction of this 1km tube is more complex than one might think, with four different construction methods used to overcome technical difficulties.


They are the drill-and-blast method at Scenic Hill, the mined tunnel method underneath the Airport Road section, the cut-and-cover method at the reclamation area, and the box-jacking method of the tunnel box segment underneath the Airport Express Line.


Ms Poon said very stringent safety measures are required for the section of the tunnel constructed by the drill-and-blast method to protect the aviation fuel tank nearby, as well as the angle station for the Ngong Ping 360 cable car and also the Airport Express Line.


“So (we) put a vibration monitoring system to monitor any vibration to ensure that all these facilities are not affected by it,” said Ms Poon.


The first cross-boundary land link will significantly slash travel time between the three cities, with a trip from Hong Kong International Airport to Zhuhai reduced from four hours to about 45 minutes.


It is expected to reinforce Hong Kong as a regional commerce, transport and logistics hub.

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