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Advisory Council on the Environment

Lantau North-South Road Access

(ACE Paper 2/2001)
For discussion

PURPOSE

This paper seeks Members' views on the proposed way forward for improving the north-south access of Lantau.

BACKGROUND

2. Tung Chung Road is a substandard one-lane village road with sharp bends and steep gradients. The opening of the Lantau Link and the new airport has stimulated the traffic demand between north and south Lantau and exacerbated the traffic situation on Tung Chung Road. The number of traffic accidents has increased from 7 in 1997 to 43 in 2000. We need to introduce improvements to the north-south access of Lantau to alleviate the safety problem.

3. In November 1996, we carried out a feasibility study on the improvement of Tung Chung Road to 2-lane standard. The study found that after widening of the road along the existing alignment (on-line widening), the road would still have 4 km of substandard gradient, of which 500 m would have a gradient of 20%. Moreover, the works would affect about 10 hectares of the Country Park.

4. If the gradients are to be improved to the normal standard, a meandering alignment (off-line widening) with sharp bends across the Tung Chung valley will have to be adopted, which would affect about 13 hectares of natural woodland and 20 hectares of Country Park affected. The on-line widening scheme was presented to the Country Parks Committee (CPC) under the Country and Marine Parks Board (CMPB) in March 1997. The CPC expressed concern about the impacts of the works to the Country Park, and advised other alternative north-south routes should be considered.

5. We subsequently developed an overland alignment between Mui Wo and Tai Ho Wan with a view to replacing Tung Chung Road. However, the Director of Environmental Protection (DEP) considered that the alignment would result in potential environmental impacts. These include substantial habitat loss of woodland, adverse impact on areas of ecological significance including Tai Ho Bay and Tai Ho Stream which is a designated Site of Scientific Interest (SSSI) being recognised as one of the most ecologically valuable fresh water streams in Hong Kong, and disturbance to ecologically valuable fauna and bird species.

6. On 13 November 2000, the Director of Environmental Protection (DEP) confirmed that the Environmental Impact Assessment (EIA) Report of the proposed Lantau North-South Road Link between Mui Wo and Tai Ho Wan did not meet the requirements of the Technical Memorandum of the EIAO and the study brief.

ALTERNATIVE SOLUTION

7. Since the Mui Wo - Tai Ho Wan alignment is unlikely to be acceptable from the environmental point of view, it is a matter of urgency to identify an alternative solution to improve the north-south access of Lantau Island. An inter-departmental working group has looked into the following possibilities -

  1. tunnel option;
     
  2. a new overland alignment; and
     
  3. widening of Tung Chung Road.

Tunnel Option

8. While a tunnel option will have less direct environmental problems, essential safety requirements demand separate compartments for traffic in opposite directions, with enough space for vehicles to overtake in case of breakdown in each direction. This will require the construction of a dual-2 tunnel which will have over-provided for the traffic demand and may induce pressure to open up South Lantau for further development. A twin tube tunnel will also incur a very high capital cost of about $5 billion and an annual recurrent maintenance cost of $100 million. Moreover, the tunnel portal areas and the associated approach roads, particularly in Mui Wo, would have significant environmental and land resumption implications. All relevant departments agree that the tunnel option should not be pursued.

A New Overland Alignment

9. The possibility of finding a new alignment overland was thoroughly investigated. Initially a corridor between Mui Wo and Siu Ho Wan appeared plausible. However, investigation and site visits revealed that the road would have a very steep gradient at the northern shore along Siu Ho comparable to the most dangerous part of the existing Tung Chung Road, unless it adopted a long zigzag alignment, resulting in severe landscape and visual impact visible from North Lantau Highway. This alignment would also affect the upper part of the Tai Ho catchment area which is environmentally sensitive and should be avoided as far as possible. A connection to the South Lantau Road at Mui Wo would encounter similar difficulties as the southern connection of the tunnel option as mentioned in paragraph 8. All relevant departments agree that no feasible overland route could be identified.

Widening of Tung Chung Road

10. We have re-examined the feasibility of widening Tung Chung Road. We found that by adjusting the alignment, accepting a maximum gradient of 15% and not provide a climbing lane, we could minimise the impact on the environment and the area of Country Park to be affected would be reduced from 20 hectares to 15 hectares.

PROPOSAL

11. Having exhausted all other options, we believe widening of Tung Chung road is the most promising solution.

12. Widening of Tung Chung Road is always not an easy task in view of the difficult terrain, the potential impact on the Country Park and on other environmentally sensitive areas such as Tung Chung Stream. Traffic would to a certain extent be affected when the works are carried out. We will make necessary compromise on the technical requirements such as accepting a steeper gradient, with additional traffic management measures including the installation of arrester beds, central dividers at certain road bends and enhanced warning signs. In view of its difficult topography, the upgraded Tung Chung Road will still have to be closed to general traffic. We will continue to regulate access at the northern end of Tung Chung Road. Emergency access will be allowed.

13. We will minimise the impact of the widening works on Tung Chung stream, ranked in importance in ecological terms only second to Tai Ho stream. The destruction of woodland habitat will also be handled sensitively. Tung Chung stream lies in the valley west of the existing Tung Chung Road, mostly in the northern section where the gradient of the road is within the safety limit. We propose to widen this section of Tung Chung Road on-line, and to the eastern side. The existing Tung Chung Road will serve as a buffer to any run-off from the work site during construction to minimise the risk of polluting the stream. Usual design standards will be relaxed to the minimum acceptable to minimise cutting of slopes and encroachment on the Country Park.

14. Dense woodland lies on both sides of Tung Chung Road in the middle and southern sections, where off-line widening is necessary to achieve the minimum safety gradient. The western side consists of ecologically more important natural woodland. The eastern side consists mainly of plantations and tall shrubland. We propose generally to avoid encroachment on the natural woodland to the west even though this may mean deviating further away from the existing Tung Chung Road. The project will also include compensatory planting of trees and landscaping to mitigate environmental disturbance.

15. With all the above measures, we are confident that the impact of the widening works on the Country Park would be reduced to the minimum.

16. A site plan illustrating the preliminary recommended alignment is at the Annex.

17. The cost of the widening scheme is estimated to be about $1 billion. We anticipate that the widening works will be completed in end 2006. The widening works will be carried out in sections, and where feasible each section will be opened to traffic as it is completed to bring about local improvements.

ADVICE SOUGHT

18. Members are invited to provide comments on the proposal to proceed with the Tung Chung Road widening scheme.

Transport Bureau
February 2001

 

 

 

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Friday, 28 April, 2006