The majority of the Hong Kong tunnelling market is about to pause as several major projects are completed and others await approval but, despite this, the use of underground space is a big topic in a densely populated area where people, buildings and infrastructure all jostle for space.
The last six years or so have been “seriously busy”, says Arup associate director James Rickard, but many of the large tunnelling projects – the MTR West Island Line Extension, South Island Line and Kwun Tong Line extension have been completed. The Express Rail Link high-speed line from West Kowloon to Guangzhou, China, and the first phase of the Sha Tin to Central Link and several major highway tunnel projects – are nearing completion.
“Tunnelling has been quietening down for the last couple of years,” says David Salisbury, project manager, SCL civil at MTR, Hong Kong’s railway operator, and secretary of the Hong Kong Tunnelling Society. “MTR has had five major projects on the go but we’re now down to the last two, the Express Rail Line [XRL] and the Shatin Central Link [SCL].” XRL and the first phase of SCL are at fit-out stage. The cross harbour second phase of SCL will complete tunnelling works in early 2018. MTR does have seven other projects in various stages of planning but these are subject to government backing and funding approval which, along with much infrastructure work in Hong Kong, is becoming mixed up in political wrangling between the government executive and legislative branches.
Infrastructure spending has become highly politicised in recent years with some Legislative Council (LegCo) members using their vote to show their dissatisfaction with overall government policy. This was certainly the case during the term of the former chief executive CY Leung, who stood down in June, and it remains to be seen whether attitudes will change under new chief executive, Carrie Lam.
“There’s been a lot of filibustering within LegCo and they’ve been rejecting or not approving funding for a lot of infrastructure projects,” says Rickard. “It’s hoped that Carrie Lam can get things going again because if she doesn’t, work is going to drop off and a lot of people, including local workers, will be laid off.” “Some LegCo members seem to believe that spending on infrastructure is money wasted,” says Salisbury. “It’s having quite a significant impact on the industry. Several projects are going backwards in terms of funding and start dates.”
As the amount of tunnelling work in Hong Kong is decreasing, so too is the number of skilled workers. “At the moment contractors are starting to shed some of the workforce,” says Rickard, adding that the number includes skilled locals who will be lost to other industries, while overseas engineers will be drawn away from Hong Kong to the more buoyant markets elsewhere.
The situation is frustrating when, if it weren’t for the political stand-offs, there are a large number of projects that could proceed.
“It’s a great shame that we’re running down and losing more and more staff towards the end of the year, never mind the workers for all our contractors, and there are projects sitting on the shelf, gathering dust,” says Salisbury. “Even when they are brushed off there will be a long lead-in for many of them so I expect there’s going to be a lull in the market for the next three to five years.
“We knew this current phase of work was coming to an end but we all hoped there would be more new projects getting moving sooner.”
PROJECTS
Among the projects that have faced delays is the Central Kowloon route, a 4.7km-long, dual three-lane road connecting the West Kowloon reclamation and the proposed Kai Tak development on the former airport site. The route includes a 3.9km tunnel and will involve a combination of drill and blast, cut and cover and some TBM work.
An Arup-Mott MacDonald joint venture is carrying out the detailed design. The project is awaiting final approval from the LegCo Finance Committee and construction is scheduled to start early next year and be completed in 2025.
MTR also has plenty of potential work on the drawing board – the North Island line, extensions to the Tseung Kwan O and Tung Chung lines, and a northern extension connecting east and west lines – but progress depends on government support and funding.
MTR is a private company that has traditionally operated a rail/property model to finance the railway construction, although on recent projects other financial models have been used. Although it is not subsidised by the government, the rail/ property model is reliant on being granted land rights above and around the stations. As the network expands this method of financing the construction becomes less sustainable and MTR in partnership with government may have to be “more imaginative” in future, says Salisbury.
“It’s the law of diminishing returns. When you build something that moves people around more efficiently it doesn’t mean you bring more people onto the system; it just means you have more railways to run. There’s not a large net increase in revenue to pay for what is often a very expensive piece of infrastructure,” he says.
Another project facing possible delays is the relocation of the Sha Tin Sewage Treatment Works to underground caverns. It’s in the final design stage and is due to go out to tender by the end of the year.
The plan is to put all the sewage treatment works underground, releasing land for much-needed housing. “There’s such a shortage of land next to major infrastructure this is probably a direction the government will consider,” says Rickard.
Salisbury describes Hong Kong’s housing demand as “immense” and consequently, prices are eye-wateringly high. “Cheap” housing in a 36-storey block in the New Territories costs around USD 1,987 per square foot; on Hong Kong Island the figure can easily reach USD 5,270 per square foot.
“Houses are getting smaller and prices are extraordinary. It beats London hands down,” he says. “There’s so much money coming in from mainland China that whenever a new housing development goes up there’s a queue of buyers.”
Hong Kong’s hilly terrain limits the growth of urban areas but the strong granite and volcanic rocks underlying those hills are well-suited to rock caverns. The government has been exploring the possibility of caverns since the 1980s and in 2011 it commissioned Arup to investigate. The study, Enhanced Use of Underground Space in Hong Kong, found that 64 per cent of Hong Kong’s land area has high to medium suitability for large-scale cavern development. Facilities located close to these areas and in the urban fringe are particularly suited for relocation to rock caverns.
The study also identified five strategic cavern areas that could accommodate multiple government facilities, with good accessibility and sufficient area to allow integrated strategic cavern development. “A square foot of real estate in Hong Kong is about as valuable a piece of land there is on the plant so the finances of underground caverns works; the challenge is getting people to buy into it,” says Salisbury.
The concept is not new. The University of Hong Kong relocated two reservoirs underground and there are other small capacity sewage treatment and waste transfer facilities, but the Sha Tin project would be the first on a large scale.
Caverns could also be used to accommodate columbarium, which at present are often on prime real estate. One existing disused underground explosives magazine is being developed for such use.
“It’s considered lucky to have your relative’s ashes on a hillside with mountains behind and sea in front. There are cemeteries sitting on some nice promontories which could be considered high-value real estate,” says Salisbury.
“Underground columbariums hark back to Roman times so there’s nothing new about the concept, it’s just reinventing it.” One transport project that is under way, and has been making headlines, is the Tuen Mun-Chep Lap Kok link for which contractor Dragages has used the world’s largest diameter TBM – a 17.6m diameter machine – as well as two mix-shield TBMs of 14m diameter. The project involves construction of a 9km dual two-lane carriageway between Tuen Mun South and North Lantau and includes Hong Kong’s deepest, largest and, at 5km, longest sub-sea road tunnel between Tuen Mun Area 40 and the Hong Kong-Zhuhai-Macao Bridge Hong Kong Boundary Crossing Facilities. At Tuen Mun Area 40 around 16.5km of land has been reclaimed to provide the northern landfall for the tunnel.
It has also required 42 cross-passages which have mostly been driven with two mini TBMs.
“They’ve been driving short 10-12m headings between the two very large diameter tunnels using a TBM with a six-week cycle time so every three weeks they’re producing another cross-passage. It’s a fascinating and very impressive project,” says Salisbury. Added to this, the work is being carried out at up to 6 bar hydrostatic pressure so Dragages is using saturation diving techniques to undertake maintenance on the TBM cutterheads The machines are equipped with a number of Bouygues’ patented technologies which enable real-time mapping of rock faces and robotic detection of damage on the cutterhead, reducing the need for manual inspections under hyperbaric conditions.
Real-time face mapping using instrumented disc cutters has been used by Dragages HK (a subsidiary of Bouygues) on several of the MTR projects for the past eight years or so. Salisbury was initially sceptical about its efficiency but is now a convert.
“It puts money into the cost of the machine but it’s proved itself very reliable. As well as giving a good indication of the hard spots and the general wear on the cutters, especially when you’re in mixed ground, if you hit anything square or vertical you know you’ve hit something manmade,” he says.
An unexpected benefit of the technology is the positive PR it can provide. It can reassure stakeholders that everything is going to plan and show site visitors a real-time comparison between the actual and expected geology at the excavation face, says Salisbury. On SCL, a 17km stretch linking existing lines on MTR’s rail network, a variable density TBM was used for the first time in Hong Kong.
Dragages HK and Bouygues Travaux Publics used the machine to excavate one 540m-long tunnel.
“The drive was very shallow (only one diameter of cover along much of its alignment) in very challenging ground, with undocumented fill material in the crown. It’s been very successful,” says Salisbury.
After delays in funding approval work is now under way on the Tseung Kwan O – Lam Tin tunnel. The 4.2km-long dual two-lane highway, which includes a 2.6km tunnel, is designed to accommodate the anticipated increase in traffic resulting from housing developments in Tseung Kwan O District. The tunnel passes under Cha Kwo Ling village and will be excavated by drill and blast. The USD 1.1bn construction contract was awarded to Leighton Contractors (Asia) Ltd in joint venture with China State Construction Engineering (Hong Kong) in July last year.
