Provisional Legislative Council
Panel on Transport andBACKGROUND
Panel on Planning, Lands and Works
Joint meeting on 13 March 1998
Information Note on Central Kowloon Route
A paper [PWSC(97-98)133] for upgrading Item 582TH - Central Kowloon Route - detailed design fees and site investigations, was considered by the PWSC at its meeting on 17 February 1998. Members requested further information as to why a dual-2 lane tunnel is recommended instead of a dual-3 lane tunnel. This paper provides the information requested.
RECOMMENDED DUAL-2 TUNNEL OPTION
2.The east-west traffic movements in Kowloon are currently catered for mainly by Lung Cheung Road, Boundary Street, Prince Edward Road, Argyle Street and the Gascoigne Road flyover. Apart from Lung Cheung Road at the northern end of Kowloon, the rest of the existing east-west road links across Central Kowloon are district distributors or local distributors with frequent frontage access and signal controlled junctions. Most of these routes are already operating at full capacity.
3.The proposed Central Kowloon Route (CKR) will provide a high capacity segregated trunk road for east-west traffic in Central Kowloon. This will help relieve congestion on the existing east-west roads, principally Lung Cheung Road, Boundary Street, Prince Edward Road, Argyle Street and the Gascoigne Road flyover.
4.We evaluated over 30 route options across the Kowloon Peninsula in the study on alternatives and confirmed that a tunnel route north of the Gascoigne Road flyover, passing through To Kwa Wan and connected to the planned South East Kowloon Development (SEKD) represents the best alignment option for the route, taking into consideration connection opportunities with the existing and planned road networks, geotechnical conditions, rehousing requirements, demolition and land clearance, traffic impacts and implementation costs and risks.
5.The recommended dual-2 tunnel option for the CKR (Figure 1) will connect the existing Yau Ma Tei Interchange and the proposed road network of the SEKD, via side-by-side tunnel boxes along the north of the Gascoigne Road flyover and a double-deck tunnel in To Kwa Wan. We have examined whether a dual-3 option should be pursued but have rejected them for the reasons explained below.
DUAL-3 SHALLOW CUT & COVER TUNNEL
6.The alignment and layout of a dual-3 tunnel (Figure 2) would be basically the same as the recommended dual-2 tunnel, again with side by side tunnel boxes at the western end and double deck tunnel boxes at the eastern end.
7.Compared to the dual-2 tunnel option, a dual-3 tunnel option would create the following problems :
DUAL-3 DEEP TUNNEL OPTIONS
- On the western end, the existing Yau Ma Tei Interchange will need to be structurally modified, and the West Kowloon Highway locally widened to cope with increased traffic flow to/from the CKR. Additional underpinning of the West Kowloon Corridor will be required for the wider tunnel to pass beneath. In addition to the 4 Government buildings which have been identified to require to be demolished under the recommended dual-2 tunnel option (i.e. Kowloon Government Offices, Yau Ma Tei Multi-storey Car Park Building, Yau Ma Tei Jockey Club Specialist Clinic Extension and Yau Ma Tei Police Station), the Yau Ma Tei Jockey Club Specialist Clinic will also need to be demolished, and additional Urban Council facilities and the main building of the Methodist College will be affected.
- At the eastern end, a large number of buildings will have to be demolished to accommodate the wider dual-3 tunnel box. Our preliminary estimates are that some 3000 to 4000 residents will be affected. The proposed dual-2 option would necessitate far less land clearance and fewer rehousing numbers. We would only know the exact details during the detailed design and investigation stage and we would endeavour to minimise the land intake to the minimum essential for the CKR works.
8.Alternatively, if dual-3 deep tunnel options were proposed, the following problems will ensue :
- On the western end, the problems will be similar to para 7(a) above.
- On the east side, deep tunnel options can be further divided into "very deep" and "medium deep" tunnels and their different impacts are separately considered as follows -
- The invert of the "very deep" tunnel (Figure 3) would have to be about 76m below ground in To Kwa Wan to remain in rock and thus avoid impact on buildings in the area. The tunnel would have to travel a much longer distance than the recommended dual-2 tunnel option to rise back up to the ground level. This means that the tunnel portal would be either at the northern or eastern extremity of the SEKD, and would not be technically feasible to connect with the proposed road network in the desired location. The route would therefore not be able to fulfil its main purpose of serving the SEKD.
- The medium depth tunnel (Figure 4) overcomes the major drawback of the deep tunnel in that the main connections with the SEKD can be provided albeit in a less desirable way than the recommended dual-2 tunnel. The invert of the tunnel will be about 51m below ground in To Kwa Wan. At this depth, the tunnel is in mixed ground, which will lead to problematic building settlement during construction. To reduce settlement impacts on adjacent buildings, the tunnels will be split into two separate 3-lane tunnels passing under separate existing roads. Even so, the tunnelling works are very difficult to construct and would lead to widespread pavement/building settlement and potential damage to buildings. Preliminary assessment showed that some 81 buildings could be affected and would require substantial foundation strengthening/replacement. There is no guarantee that strengthening/replacement of foundations for these buildings will be successful, and urgent evacuation of the residents of the affected buildings will be necessary at short notice if excessive settlement is detected during construction. In addition, the ground floor/basement of each affected building would have to be vacated to provide works area for the foundation improvement works. The estimated cost of these works alone is in the order of HK$6.0 billion.
9.It is because of the above considerations mentioned in paragraphs 6 to 8 that a dual-3 tunnel option of the CKR is not recommended for implementation. The recommended dual-2 tunnel option represents the best option to provide necessary relief to the east-west road corridors in Kowloon Peninsula.
10. The various sub-regional planning and feasibility studies conducted by Government (including the Central and East Kowloon Development Statement, the West Kowloon Reclamation Comprehensive Traffic Analysis Review and the Environmental Impact Assessment, and Feasibility Study for the South East Kowloon Development) have all assumed a dual-2 land CKR in the derivation of their development plans.
11.The Central Kowloon Traffic Study and the West Kowloon Reclamation Traffic Study (completed in 1990), and the traffic forecasts conducted under the Central Kowloon Route - Study on Alternatives (completed in early 1998), confirmed that a dual-2 tunnel route will provide adequate relief to the congested east-west ground level routes in Kowloon Peninsula with the overall forecast volume/capacity (V/C ) ratio of 1.0 in the year 2011 across the N-S screen line. Without the CKR, the forecast V/C ratio across a N-S screen line in Kowloon Peninsula will be 1.2 in 2011 and widespread congestion throughout the day can be expected with the extensive planned developments in the Kowloon Peninsula.
12.To further increase the east-west capacity across Kowloon Peninsula, we will investigate the feasibility of improvement measures along the existing east-west corridors, including the widening of Gascoigne Road flyover and provision of flyovers/underpasses across the busy junctions along these corridors. Under the CKR project, the Yau Ma Tei Multi-storey Car Park building will be demolished and provisions have been allowed in the existing structure of the Gascoigne Road flyover for its widening and extension thereafter (Figure 5). In the longer term, we intend to examine the feasibility of a southern connection between West Kowloon and South-east Kowloon via Salisbury Road. Opportunities for further improvements to the road network in Kowloon Peninsula will also be examined in CTS-3.
PROPOSED IMPLEMENTATION PROGRAMME
13. Subject to Members' support, we intend to seek Public Work Sub-committee and Finance Committee's funding approval respectively on 25 March 1998 and 3 April 1998. We intend to start the detailed design and site investigation works in May 1998. We plan to gazette the project under the Roads (Works, Use and Compensation) Ordinance in late 1999. We would consult the relevant Provisional District Boards, the Provisional Urban Council and the Advisory Council on the Environment. Subject to the satisfactory compliance with the necessary procedural and legislative requirements, the tentative programme is to commence construction of the proposed CKR in late 2003 for completion by late 2007. We would however closely monitor the overall progress with a view to advance the construction works whenever possible.