If you thought rush-hour crowds were the over-riding inconvenience of travelling on the MTR, think again. Noise annoys - at least it does on the system's ageing Tsuen Wan line. A survey by a watchdog group has found decibel levels of as high as 98.4 - equivalent to the noise level of continuous construction piling - on the line, and they want the MTR to quieten things down for the tens of thousands of people who use the line daily. Rail chiefs have introduced newer, quieter trains on other lines, and yesterday they explained what they were doing to reduce noise on the older Tsuen Wan line. Federation of Trade Unions lawmaker Wong Kwok-hing and the Public Services Monitoring Group had asked the MTR Corporation to introduce ways to cut noise on trains and in stations after recording a high reading of 98.4 decibels on April 18 on a train between Tai Wo Hau and Tsuen Wan. The World Health Organisation has said that frequent exposure to noise levels of 85 decibels or above could cause stress and even hearing problems. The MTR Corp's manager of technical and engineering services, David Leung Chuen-choi, said: 'There is no standard or index to monitor in-train noise levels, but we have adopted measures to minimise noise. ' Up to 31 trains can travel on the red Tsuen Wan line per hour, and wear-and-tear can roughen both rail tracks and wheels, causing greater friction and more noise. A spokesman for the railway company said noise was inevitable on trains, but the firm had always made it a priority to improve the in-train environment and had adopted measures throughout the years to reduce noise. 'Yes, the Tsuen Wan line is in general noisier than the Island line, but I'm used to it,' said one Form Three student who takes the train to school. One man who takes the line to work also thought its trains were noisier than those on the Island line, but said the noise level was acceptable. All trains on the Tsuen Wan line had wheel dampers added 10 years ago, reducing noise from vibration and resonance. Stick lubricators are also attached to train wheels to make them run more smoothly. Leung said that trains were checked every 60 days, and that both train wheels and rail tracks went through grinding every six months to smooth out any roughness. The Tsuen Wan line started running in 1982 and the same model of train, bought at different times, has been used all that time. Leung said that two new trains were going through testing and, if found suitable, would replace some of the system's older trains by the end of this year or the beginning of the next. Wong said that while yesterday's noise-level readings were more acceptable, he urged the MTR Corp to upgrade noise-reducing measures on trains and at station areas. 'With the fare increase next month and the corporation's HK$12 billion income last year, I hope they will use some of the money to get more new trains.' Wong said MTR representatives had promised to conduct research to improve sound-insulation for train doors this year, but Leung said the project was still in the initial stages and refused to give more details or a timeline.