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Following is a question by the Hon Andrew Cheng Kar-foo and a written reply by the Secretary for Transport and Housing, Ms Eva Cheng, at the Legislative Council meeting today (October 29):
Question:
I have received complaints from residents of the Central and Western District that the vent shaft of the West Hong Kong Island Line proposed to be built by the MTR Corporation Limited (MTRCL) at Hill Road will cause noise and air pollution nuisance to residents nearby. In this connection, will the Government inform this Council whether:
(a) it has found out from MTRCL the impact of the vent shaft on the local environment, including the environmental impact data in terms of air quality and noise, etc.; if not, of the reasons for that; and
(b) it has suggested to MTRCL to relocate the vent shaft to another area; if it has, of the relevant details and the relocation cost involved; if not, the reasons for that?
Reply:
President,
The West Island Line (WIL) is an extension of the existing MTR Island Line from Sheung Wan to Kennedy Town with two intermediate stations at Sai Ying Pun and the University of Hong Kong. The MTRCL is now working on the detailed design of the WIL. According to its Project Proposal, there will be a ventilation shaft at Hill Road to serve the station at the University of Hong Kong. My reply to the questions regarding this proposed ventilation shaft is as follows:
a) Ventilation shafts are an integral part of an underground railway system. It will enable air exchanges inside the stations and tunnels with the outside areas. As the trains are powered by electricity, combustion of fossil fuels is not required and hence no harmful or hazardous gases are discharged. Furthermore, the rail tracks and tunnels are washed regularly in order to maintain the cleanliness of the railway.
Apart from that, the MTRCL has conducted air quality tests by setting up a monitoring point at an existing ventilation shaft of the Central Station. The dust level obtained from the monitoring point is very close to those readings obtained from a nearby roadside air quality station set up by the Environmental Protection Department (EPD). This has demonstrated that air exhausted from the ventilation shaft dose not cause any adverse impacts on the air quality of the surrounding areas.
In accordance with the Environmental Impact Assessment (EIA) Ordinance, the MTRCL has submitted the EIA report of the WIL to the EPD, and the report has been made available for public inspection. The report has addressed the key environmental impacts during the construction and operation of the WIL, including air quality, noise, etc. According to the report, the air quality inside railway stations and train compartments during peak hours complies with the Level 1 standard of the "Practice Note for Managing Air Quality in Air-conditioned Public Transport Facilities- Railways" issued by the EPD, i.e. the hourly average of carbon dioxide concentration should be less than 2,500 parts per million (ppm). This indicates that the quality of air exhausted from the stations and the tunnels through the ventilation shaft is good.
As far as noise is concerned, the operation of ventilation shafts has to comply with the requirements stipulated in the Noise Control Ordinance. The stations and the plant rooms that house the ventilation fans of the WIL are in general far below ground with some distance away from the ventilation shaft. Moreover, given that the exhaust air speed is not high and suitable acoustic systems are installed, the noise impact to the public in the vicinity is insignificant and is in compliance with the requirements under the EIA Ordinance.
As regards visual impact, the MTRCL will strive to reduce the scale of the ventilation shaft. Its outlook appearance will be designed to blend with the surroundings so that any visual impact will be minimized.
The Transport and Housing Bureau and the MTRCL have been in close liaison with the Central and Western District Council (C&WDC) and the residents. In order to ease residents' concerns about the proposed ventilation shaft, many briefings and site visits, including visits to ventilation facilities of current stations have been arranged for the members of the C&WDC and the residents.
b) Locations of ventilation shafts are constrained by the design and alignment of the railways. As the Western District is a densely populated area, it is difficult to find suitable locations for the railway facilities. The MTRCL has studied various alternative locations near Hill Road for setting up the ventilation shaft. The results of the study are attached (see Annex).
The above studies mainly concern technical problems and the impact on the residents rather than cost increase which may incur, which is not the major factor in the consideration. After assessing the various factors, the proposed location under the flyover at Hill Road is the more preferable option. As aforesaid, the MTRCL will make every effort to enhance the ventilation shaft structure and to design its external appearance to blend with the surroundings, with a view to minimizing any visual impacts.
Ends/Wednesday, October 29, 2008
Issued at HKT 12:46
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