PWSC(97-98)50
For discussion
on 15 October 1997

ITEM FOR PUBLIC WORKS
SUBCOMMITTEE OF FINANCE COMMITTEE

HEAD 706 - HIGHWAYS
Transport - Roads
459TH-Wing Tai Road flyover and improvements to associated road junctions

Members are invited to recommend to Finance Committee to upgrade 459TH to Category A for the construction of Wing Tai Road flyover and the implementation of improvement works to associated road junctions at an estimated cost of $128.33 million in money-of-the-day prices.

PROBLEM

The junction of Chai Wan Road/Wing Tai Road is unable to cope with the future traffic demand arising from developments in Siu Sai Wan.

PROPOSAL

2.The Director of Highways, with the support of the Secretary for Transport, proposes to upgrade 459THto Category A at an estimated cost of $128.33 million in money-of-the-day (MOD) prices to construct a new flyover from Chai Wan Road to Wing Tai Road and to implement improvement works to the associated road junctions.

PROJECT SCOPE AND NATURE

3.The scope of the project comprises -

1. construction of a two-lane flyover to carry the through traffic from Chai Wan Road westbound to Wing Tai Road northbound;

2. widening of a section of Wing Tai Road between Sheung On Street and Chai Wan Road;

3. modification of the junction layout of Chai Wan Road/Wing Tai Road and Chai Wan Road/Sun Yip Street;

4. construction of the associated traffic islands, footways and landscaped area, and traffic aids; and

5. provision of indirect noise mitigation measures to about 252 residential flats and two schools affected by the road widening project.

JUSTIFICATION

4.The section of Chai Wan Road east of Wing Tai Road is the main access to the Siu Sai Wan area. The Island East Traffic Study completed in 1993 concluded that the existing Chai Wan Road/Wing Tai Road junction will be unable to cope with the future traffic demand when Siu Sai Wan is fully developed in 2001. We anticipate that by then the traffic demand on the existing Chai Wan Road/Wing Tai Road junction would exceed its handling capacity by 5%. We propose to improve the road capacity at the junction by constructing a two-lane flyover across the junction to allow through traffic from Chai Wan Road westbound to Wing Tai Road northbound. In conjunction with the construction of the flyover, we also propose to implement the associated improvement works listed in paragraphs 3(b) to 3(d) above. The Chai Wan Road/Wing Tai Road junction will have a reserve capacity of 25% in 2001 when the proposed improvement works are in place.

5.As a result of the proposed improvement works and the eventual increase in traffic flow, two schools⁽¹⁾and about 252 dwelling units near the ChaiWan Road/Wing Tai Road junction will be exposed to noise levels higher than the upper limits stipulated in the Hong Kong Planning Standards and Guidelines (HKPSG). Due to prevailing site conditions, direct mitigation measures in the form of enclosures, roadside barriers and laying of noise reducing surfacing materials are neither effective nor practical to reduce the level of noise. We need to provide indirect noise mitigation measures in the form of window insulation and air-conditioning to these affected dwelling units and schools.

FINANCIAL IMPLICATIONS

6.We estimate the capital cost of the proposed works to be $128.33 million in MOD prices (see paragraph 7 below), made up as follows -

7.Subject to approval, we will phase the expenditure as follows -

8.We have derived the MOD estimate on the basis of the Government's forecast of trend labour and construction prices for the period 1998 to 2003. We will tender the works under a re-measurement contract because the quantities of the foundation works for the elevated structures may vary depending on actual site conditions. The contract will provide for adjustments to the tender price due to inflation as the contract period will exceed 21 months. We will employ consultants to carry out a detailed study to ascertain which premises will be affected by future traffic noise and put up recommendations on the indirect noise mitigation measures required. The consultants and their resident site staff will administer the implementation of these measures. A breakdown by man-months of the estimates for consultants' fees is at the Enclosure.

9.We estimate the additional annually recurrent expenditure to be $723,000.

PUBLIC CONSULTATION

10.We consulted the Traffic and Transport Committee of the Eastern District Board (EDB) on 24 January 1995 and members supported the project. The Committee however urged Government to closely monitor the traffic situation during the construction period to avoid creating traffic congestion in the area.

11.We presented the findings of the Environmental Impact Assessment (EIA) to the EDB on 20 July 1995 and to the Yee Wan and Wan Tai Area Committees of the Eastern District on 13 September 1995. Both the EDB and the area committees did not agree with the recommendation of the EIA to provide only indirect technical remedies in the form of window insulation and air-conditioning. EDB members requested the Government to consider adopting direct technical remedies, including the provision of a noise enclosure on the flyover.

12.The EIA study had fully examined the options of direct technical remedies, including the use of noise enclosure, barriers and noise reducing surfacing materials. We found such options to be either impractical or ineffective for the following reasons -

1. Noise enclosure on the flyover

2. We consider the option to be ineffective in reducing either the noise level or the number of affected premises. Most of the road noise is generated by at-grade traffic. The noise enclosure can only reduce the noise levels by about 1-2 dB(A) to a limited number of affected premises. Even if the noise enclosure is installed, noise levels at all affected dwelling units will still exceed the limits stipulated in the HKPSG. We estimate the enclosure will cost about $47.7 million at December 1996 prices to construct.

3. Provision of noise barriers on the flyover

   Compared with the noise enclosure option, we consider the noise barrier option an even less effective noise mitigation measure. The barriers can only reduce noise by about 1 dB(A) to a limited number of premises. We estimate the barriers will cost about $6.8 million at December 1996 prices to construct.

4. Installation of roadside barriers at ground level

   We have also found this option impractical. The presence of noise barriers will restrict access by emergency vehicles unless openings are provided at close intervals. Yet the presence of openings will significantly degrade the effectiveness of the barriers in reducing noise. Furthermore, roadside barriers also conflict with pedestrian walkways and drivers' sight lines.

5. Laying of noise reducing surfacing materials

   The materials are only suitable for straight and level roads with high speed free flow traffic. They are not suitable for application on flyovers and road junctions as provided in this project. The turning and braking operations of vehicles will quickly wear out the road surface, necessitating frequent patching and relaying of the road surface materials. Besides high maintenance costs, such maintenance works will cause disruptions to traffic.

13.We explained these findings to the Environmental Improvement Committee (EIC) of the EDB on 21 November 1995. However, EIC members of the EDB were not convinced and passed a resolution in favour of direct technical remedies.

14.In parallel with the consultation with the EIC of EDB, we gazetted the project under the Roads (Works, Use and Compensation) Ordinance on 20 October 1995 and 27 October 1995 and received two objections. One of the objections was raised by the EIC of the EDB. Another objection was jointly raised by some EDB members, local groups of residents, and the Ching Kai Nam Community Service Office. Both objections were against constructing the flyover without a noise enclosure. In view of the objections, we tried to further explain the proposal to the EIC of the EDB on 6 June 1996. However, the Committee still resolved that they objected to the construction of the proposed flyover without a noise enclosure.

15.On 11 March 1997 the former Governor-in-Council considered the objections mentioned in paragraph 14 above and over-ruled them in the public interest.

16.The Advisory Council on the Environment endorsed the EIA report on 20 November 1995.

ENVIRONMENTAL IMPLICATIONS

17.We completed an Environmental Impact Assessment (EIA) study for the project in July 1995. The study identified traffic noise as the major concern. By 2011, most of the existing residential buildings and the two schools along the proposed flyover and the widened road section will be exposed to noise levels higher than the acceptable limits stipulated in the HKPSG. Due to prevailing site conditions, direct noise mitigation measures are either ineffective or impractical to reduce the noise levels. The study identified that indirect technical remedies in the form of window insulation and air conditioners should be provided to about 460 affected dwelling units and the two schools.

18.However, with the latest information available, we forecast that the number of dwelling units adversely affected by road traffic noise would decrease with time. The Director of Housing (D of H) has a re-development programme for Chai Wan Estate⁽²⁾ . Block 10 is being demolished for the construction of a secondary school. The design of the new school has taken the EIA findings into account and incorporated noise mitigation measures⁽³⁾ within the proposed school site to mitigate the potential traffic noise impact. Block 13 is currently planned to to be demolished in 1999/2000 and the resultant site will be developed into a local open space. Therefore, if the redevelopment programme is to be implemented as planned, it will be unnecessary to provide noise insulation works to the 208 nos. of affected dwelling units in Blocks 10 and 13 identified in the EIA study because the two residential blocks will have been demolished by the time the flyover is completed. Only the remaining 252 affected dwelling units will need to be provided with noise mitigation measures at an estimated cost of $16.87 million at December 1996 prices.

19.For short-term impact during construction, we will control noise, dust and site run-off through implementation of mitigation measures in the works contract.

LAND ACQUISITION

20.The proposed works do not require resumption of any private land. The boundaries of the two public housing estates and the Chai Wan Swimming Pool will be set back by a maximum of nine metres to permit the road widening at Wing Tai Road and Chai Wan Road respectively. D of H has expressed no objection to the land alienation. The Urban Council has also approved the alienation of part of the slope near the Chai Wan Swimming Pool for the project.

BACKGROUND INFORMATION

21.Besides the re-development project on Chai Wan Estate, D of H has implemented a Home Ownership Scheme (HOS) project⁽⁴⁾at the site close to Tsui Wan Estate and in front of Wing Tai Road. The environmental consultants for the HOS project have taken into account the noise nuisance from the adjacent roads and concluded that the majority (88%) of the flats under the HOS project will be subject to noise levels within the acceptable limits. D of H will provide the remaining 12% of the flats with indirect noise mitigation measures, in the form of window insulation and air-conditioning.

22.We upgraded this project to Category B in June 1993.

23.We have substantially completed the detailed design and working drawings for the proposed roadworks using in-house staff resources. We plan to start the roadworks in April 1998 for completion in May 2000.

24.We will engage consultants in June 1998 to carry out a detailed study for the indirect noise mitigation measures and to administer their implementation in November 1998 for completion in September 2000.

25.To minimize disruption to traffic during construction, we will carry out the proposed work in stages and implement a temporary traffic diversion scheme in consultation with the Police and the Transport Department to ensure that the principal traffic flows will be maintained during all stages of construction.

26.We submitted a paper to the Public Works Subcommittee on 3 September 1997 proposing upgrading of 459TH to Category A (paper PWSC(97-98)44). The paper was withdrawn in view of Members' concerns on the effectiveness of the noise mitigation measures to be provided. Members also requested the Administration to include information on the cost of installing noise barriers in the paper when the proposal to upgrade 459TH to Category A is re-submitted to the Public Works Subcommittee. The information requested has been provided in this paper.

Transport Bureau
September 1997

(EE1104)

(1)Fung Yiu Hing Memorial Primary School and Chai Wan Faith Love Lutheran School.

(2)Chai Wan Estate has a total of fifteen blocks. With the exception of Blocks 10 and 13, we find the other thirteen blocks are not affected by the traffic noise arising from 459TH.

(3)The noise mitigation measures will include the provision of: (a) a 2.7-metre high solid boundary wall, (b) maximum buffer distance from the roads and (c) installation of air-conditioning and window insulation for classrooms that will be subject to noise levels exceeding 65 dB(A).

(4)The HOS project comprises two residential blocks and a 6-storey car park. The car park will serve to shield the two residential blocks from the traffic noise generated from Wing Tai Road. D of H has completed the construction of the HOS project and started the population intake in August 1997.

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Enclosure to PWSC(97-98)50

459TH - Wing Tai Road flyover and improvements to associated road junctions

Breakdown of estimates for consultants' fees

* MPS = Master pay scale

Notes

1. A multiplier factor of 3 is applied to the average MPS point to arrive at the full costs including the consultants' overheads and profit, as the staff will be employed in the consultants' office (as at 1.4.96, MPS pt. 40 = $55,390 p.m. and MPS pt. 20 = $22,595 p.m.). A multiplier factor of 2.1 is applied in the case of site staff supplied by the consultants.

2. Out of pocket expenses are the actual cost incurred. The consultant is not entitled to any additional payment for the overheads or profit in respect of these items.

3. The figures given above are based on estimates prepared by the Director of Highways. We will only know the actual man months and actual fees when we have selected the consultant through the usual competitive lump sum fee bid system.

(EE1104)