Hong Kong's Kowloon Canton Railway Corporation's (KCRC)'s Kowloon Southern Link, which went into service earlier this year, closes a gap in the network between two of Kowloon's major rail lines and will service one of the most densely populated and busiest areas of Hong Kong.
The HK$ 2 billion (AU$ 358 million/US$ 258 million) contract, which was delivered by the Link 200 Joint Venture (Leighton Asia, Balfour Beatty, Kumagai Gumi and John Holland), was to design and construct a new underground railway station at West Kowloon and its linking tunnels to East Tsim Sha Tsui Station.
Part of the project involved driving twin tunnels (each of which was 7 m in diameter), rather than using ‘cut and cover' methods, to avoid above-ground congestion.
However, according to the JV, planning for them was not an easy task.
Apart from normal safety and engineering considerations, the tunnels:
- went through a zone of newly reclaimed land
- passed under "heritage-listed" property
- traversed Hong Kong's notoriously variable geology - high groundwater, landfills, completely decomposed granite, soft marine alluvium and fresh granite bedrock
- were directly over the MTR (Mass Transit Railway) Tsuen Wan line's running tunnels, clearing them by only 2 m
- were ‘stacked' to fit within the relatively narrow Canton Road.
The two-level West Kowloon station is a 19 m below-ground structure with diaphragm walls, constructed in a predominantly greenfield site, part of the West Kowloon reclamation.
However, because major roads and utility services crossed the footprint of the station, multiple traffic and utility diversions were needed to facilitate construction. Besides this, old sea walls were discovered during excavation further complicating part of the project.
The structure of the station was completed in 2008, with the final fit out finished nine months later in mid-2009.
The project started in August 2005 and is scheduled for completion this year.
Project award winner
Every year, the Hong Kong Special Administrative Region (SAR) Government's Environment, Transport and Works Bureau organises the ‘Considerate Contractors Site Awards Scheme'.
This recognises construction sites where the contractor has demonstrated good site safety and environmental management, with an emphasis on minimising nuisance to the neighbourhood and passers-by.
The Link 200 JV received one of the major awards, primarily for its ‘Innovative Environmentally Friendly Design TBM Retrieval Shaft' at Salisbury Road.
Under the original design, a 160 m long section of tunnel at Salisbury Road was to be constructed by the traditional cut and cover method. However, the JV decided to excavate using its tunnel boring machine.
As a result:
- 35000 m3 less construction waste was created
- 33000 m3 less construction material was used
- reducing truck traffic by 12566 lorries and carbon dioxide emissions by about 103 tonnes.
Additionally, the joint venture recorded no major accidents, no prosecutions, created a good site safety culture and established good relations with the nearby community.