Despite a present, short-term economic recession, a remarkable enthusiasm exists in Hong Kong for building infrastructure, including major tunnel projects.
This paper provides details of current and recent bored tunnel works together with an insight into the impressive list of future underground projects planned by the MTRC, KCRC, Highways Department and Drainage Services Department for the next decade.
Current projects
As an integral, progressive, special administrative region of China, the Hong Kong Government continues to develop its infrastructure only slightly abated by the recent general recession in Asia. Bored tunnels form a key element of each new major project, most notably for transportation and utility facilities.
These works are considerable, particularly for railway tunnels for MTRC’s Tseung Kwan O (TKO) and KCRC’s West Rail extensions. The recent successful completion of the government’s first large-span, three-lane highway tunnels for Route 3 by drill and blast (one engineer’s design and one by BOT) is a notable step forward.
Other progress includes the successful use of mechanised tunnelling by hard rock TBM for completion of long tunnels in mountainous areas for WSD’s Silvermine Bay and Tai Po Aqueducts; the SSDS Phase I and Central Western and Wanchai Sewage tunnels experienced more challenging geological conditions in heavily built up areas around the harbour, affecting both budget and timely completion of the works.
Further developments are the application of hard rock TBMs for excavation of short tunnels in urban areas, due to restriction on blasting on the Quarry Bay Relief project, as well as the application of an 8.7m diameter hard rock EPBM (earth pressure balance machine) for tunnelling in severe mixed face condition at Kwai Tsing for West Rail.
Overall developments in tunnelling in Hong Kong, as shown above, are summarised as follows:
Future projects
Known future and planned infrastructure projects which contain considerable elements of bored tunnelling works. The largest of these is a future underground railway extension from Sha Tin in the New Territories via Hung Hom to the Central District on Hong Kong Island, including both the East Kowloon line and a further harbour crossing by immersed tube; an underground North Island line running from Central District via Tamar and Exhibition to Fortress Station is also planned.
The government has recently announced that the KCRC and MTRC will be competing for the first of these projects which should be completed by 2010. However, MTRC argues that patronage from the current West Rail and TKO extensions will create a demand at, or above, capacity on sections of their existing railway network, and so this line should be built by them by 2007.
Also, the Kennedy Town extension appears to be required sooner rather than later by MTRC.Lists the series of three-lane highway tunnel projects required in the near future. Works for Routes 9 and 10 are mainly at detailed design stage and should be tendered next year.
The complexities of building a tunnel below the Kowloon Peninsular have delayed execution of the Central Kowloon route. These concern the number of buildings and residents likely to be affected by the works as well as the extent and location of the new reclamation works proposed in the vicinity of the old airport at Kai Tak.
The difficulties of excavating deep, largely subaqueous tunnels for Stage I of the SSDS, by probing and grouting ahead of hard rock TBMs, include unexpected settlement, delays and cost overruns. The first contractor to take on the challenge, the Campenon Bernard/Maeda JV, is now locked in arbitration proceedings with the government and the three contractors completing the works are also experiencing difficulties.
Only the Paul Y/SELI JV has managed to complete one of the long TBM drives for the projects roughly on programme. As a result of this, and an environmental lobby, the remaining Stages II-IV are being delayed by a major review of the project.
The full paper includes: risks for each of the works, including pipe jacking, mixed face and rock tunnelling generally in Hong Kong, are also identified.
From this, it is evident that the scale and difficulty of such works continues to increase, requiring the use of more sophisticated methods of construction, the need for better methods of assessing and managing risks and for government to utilise improved, more equitable conditions of contract for such major tunnelling projects.
Conclusions
An outline of current tunnelling projects in Hong Kong is given in this paper together with an informative overview of developments in the local tunnelling industry.
The extent of these works, some of which involve innovative technical solutions for tunnelling particularly difficult ground, are impressive by international standards.
[The full paper also concludes: Conversely, attitudes within the industry towards identification, reasonable allocation and management of geological related risks fall well short of international standards.The next decade will yield a wealth of even more challenging tunnelling. However, incidents of disputes and arbitrations can be expected to reach epidemic proportions unless the government and other owners take preventative action by adopting more reasonable and equitable conditions of contract.
The one ray of light is the form of contract used for the successful implementation of the government’s first TBM project, namely that for DSD’s Tolo Effluent Export Scheme. To date the value of this simple approach has not yet been recognised in Hong Kong.]
