Traffic noise contour mapping of Matara city, Sri Lanka

Abstract

Road traffic noise in Sri Lanka is becoming a serious problem due to rapid industrialization, which could cause health problems to the civilians unless noise controlling and reduction measures are taken. “Noise contour mapping” plays a major role in planning developments of a city while maintaining the noise level at an acceptable level. Noise contour maps, have helped most developed countries to take mitigation actions to control noise levels of cities by introducing vegetation barriers, wall-type barriers, speed bumps, and by improving the conditions of the roads. This paper presents a study aimed at preparing a noise map of Matara City, located in the Southern Province of Sri Lanka. Noise measurements were carried out using a B&K Type-2250 hand held analyzer (IEC 61672-1; 2002 Class1). LAeq values of the diurnal sound level variation were used to produce noise contours. Internationally recommended IMMI mapping software was used for the estimation of traffic noise. The traffic volume, vehicular type, their speed, nature of road surface and meteorological conditions were considered. According to the results, in more than half the area of Matara city (suburb of A2, A24 & and B275 roads), the noise level exceeds the maximum allowed level of 63 dB of Sri Lanka National Environment Act. No. 47, 1980. The recorded LAeq value is around 75-80 dB at locations of traffic lights and road crossings. At some instances, LAeq more than 85 dB values were recorded, especially due to high power engines, poor exhaust systems of vehicles and some vehicle horns. The results suggest that necessary regulations have to be imposed to control the sound pollution and to avoid adverse health effects.