EXCESSIVE NOISE FROM ANG MO KIO MRT LINES (Measures to remedy)

The following question stood in the name of Mr S. Chandra Das-

Mr S. Chandra Das: To ask the Minister for the Environment (a) if he is aware of complaints by residents of the high noise level along Avenue 8 Ang Mo Kio covering the Cheng San, Chong Boon and Teck Ghee constituencies, as a result of the running of the Mass Rapid Transit lines; (b) whether his Ministry has conducted any studies on the noise level before and after the MRT lines became operational; and (c) what possible remedies, if any, can be introduced to reduce the excessive noise level experienced by the residents.

Mr Heng Chiang Meng: Question 3, Sir.

The Minister for the Environment (Dr Ahmad Mattar): Mr Speaker, Sir, at the outset of the Mass Rapid Transit (MRT) project in June 1983, my Ministry was aware that there will be noise from it. While noise cannot be totally prevented, measures can be taken to reduce it.

My Ministry had recommended guidelines on noise control to the MRTC for their trains and mechanical ventilation equipment. These guidelines were formulated after a careful study of those adopted in Japan, the United Kingdom and the United States which were then modified to suit our local circumstances. MRTC had also taken every care in the design of their tracks and the specifications for their equipment to keep noise levels to a minimum. They have also with them the services of noise consultants to further advise them on these matters.

The trains that are used comply with the noise standards specified in MRTC's tenders. In addition, continuously welded rails are used to reduce noise from the tracks.

At underground sections near high-rise buildings, tracks are laid on special floating slabs to cut down vibration and noise.

At above-ground sections, the viaduct which supports the tracks is made of concrete with high mass and damping characteristics to minimize noise that may be induced by passing trains.

These measures have been taken to ensure that the MRT is constructed with good noise control features from the start and should be adequate to reduce MRT noise to acceptable levels in most areas.

Measurements made after the trains started operating show that some areas at Ang Mo Kio Avenue 8 are noisier as a result of the MRT.

At these areas, additional noise reduction measures can still be taken. For example, the MRTC will be acquiring a rail-grinding machine to remove irregularities or corrugation on rails. Flanges of the rail wheels will be automatically lubricated to reduce squealing when the trains negotiate sharp bends. A wheel-lathe machine has also been procured which will be used to maintain the shape of the wheels at regular intervals so that they are smooth and therefore do not produce noise.

My Ministry will continue to monitor the results of these noise reduction measures closely.

Dr Ang Kok Peng (Buona Vista): Sir, I have two questions for the Minister. How many blocks of flats along Avenue 8 Ang Mo Kio are really having a higher dose of noise because of the MRT system? What other areas near the MRT system will experience a higher noise level in future when more MRT lines become operational?

Dr Ahmad Mattar: Mr Speaker, Sir, before I come to the Member's question on the number of blocks of flats along Ang Mo Kio Avenue 8, I would like to inform the House of the noise characteristics along Ang Mo Kio Avenue 8 before and after the running of the MRT trains.

My Ministry has conducted a noise survey of the area and we have found that the ambient noise level measured in the HDB flats near the MRT prior to the trains running was about 70-75 dBA. With the trains now running, noise levels between 83 and 86 dBA have been measured when a train passes by.

Sir, it must be noted that traffic noise from expressways measured at nearby flats average 75 dBA with peaks of 87 dBA. So you see, Sir, noise levels from MRT trains are therefore no worse than the present-day expressway traffic noise. Of course, it is understandable that people who live away from expressways but are now being subjected to MRT train noise will, initially, find the change annoying.

As regards the number of blocks of flats affected by the noise, Sir, the number is 11. Based on the number of storeys and the proportion of units close enough to the tracks to be affected by the noise, an estimated 550 families living in those units are likely to be exposed to noise levels between 79 and 85 dBA along their corridors. Indoors, Sir, the noise level would be reduced by 5-10 dBA, meaning that the affected families are likely to be exposed to anything between 69 and 80 dBA.

The other housing estates which have flats close to above-ground tracks are Yishun, flats in Bukit Merah area, Queenstown, Clementi, Bukit Batok, Bedok, Simei and Tampines. But as in Ang Mo Kio, I do not expect the noise levels in these areas to be more than traffic noise levels along expressways.

Mr Tang See Chim: Sir, would the Minister explain what is the meaning of "dBA" so that Members like me can understand?

Dr Ahmad Mattar: Sir, I would suggest that the Member for Chua Chu Kang have a private session with me after this.