NOISE AND AIR POLLUTION FROM MRT SYSTEM (Measures to control)

The following Question stood in the name of Dr Koh Lam Son:

Dr Koh Lam Son: To ask the Minister for the Environment what measures are being taken to control noise and air pollution from the Mass Rapid Transit System.

Mr Deputy Speaker: Dr Koh Lam Son.

Mr Chew Heng Ching: Question No. 5, Sir.

The Minister for the Environment (Dr Ahmad Mattar): Mr Deputy Speaker, Sir, at the outset of the Mass Rapid Transit (MRT) project in June 1983, my Ministry had recommended noise guidelines to MRTC for their trains and mechanical/ventilation equipment. MRTC have 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 with them the services of noise consultants to further advise them on these matters.

Sir, the viaduct which supports the tracks is made of concrete with high mass and damping characteristics to minimize noise that may be induced by vibrations from passing trains. The trains will run on continuously welded rails to minimize noise that would otherwise have been caused by the wheels running over gaps in between sections of the rail. In addition, these rails rest on ballasted trackbeds for better absorption of vibrations. At critical underground sections near to high-rise buildings, special floating slabs on the trackwork will cut down the transmission of vibration and noise to the superstructures above. These measures have been taken to ensure that the MRT is constructed with good noise control features from the start.

The noise levels of the trains have yet to be tested in actual operations. Noise measurements will be carried out when the MRT is in operation. In the last eventuality, Sir, provisions have been made on the elevated sections of the MRT line to affix noise barriers at critical sections should noise prove to be still a problem.

Sir, as the MRT trains run on electricity, no air pollution from the running of these trains is anticipated.

Dr Ang Kok Peng (Buona Vista): Sir, when the MRT is in operation, the Ministry will be monitoring the noise level. What I want to know is what will the Ministry be monitoring - the traffic noise index or the noise pollution level, or what?

Dr Ahmad Mattar: Mr Deputy Speaker, Sir, neither. We will just be measuring the sound level in dbA, or what we call the A-weighted sound level. Only for specialized studies do we measure the traffic noise index or the noise pollution level which the Member for Buona Vista has mentioned. Sir, it has been demonstrated that the A- weighted sound level correlates just as well with the other ratings, as far as subjective response is concerned. And because of its simplicity, it has been recommended for use in building codes, anti-noise ordinances and monitoring of urban traffic noise.