Noise levels of vehicles in the city of Colombo

Abstract

INTRODUCTION: Though there is concern that vehicular traffic contributes to noise pollution in the city of Colombo there is no reliable data on the noise emitted by different categories of vehicles. OBJECTIVES: Objective of this study was to determine the noise emitted by different categories of vehicles within the city of Colombo. METHODS: Vehicles in the city of Colombo could be classified into sixteen categories based on the type (bus, motor-car, three-wheeler etc), technology (two-stroke, four-stroke, petrol, diesel) and size (light, heavy etc). Nine to 16 vehicles from each category were selected by quota sampling. Sound pressure level (SPL-the magnitude of sound) and maximum sound level (LAmax) of the engine and horn of the selected vehicles were measured according to ISO 5130:2007(E) standards. RESULTS: Measurements were made on 184 vehicles. Median SPL of vehicles ranged from 80dB in cars to 105dB in diesel three-wheelers. SPL of six categories of vehicles were more than 100dB. SPL of four and two stroke petrol three-wheelers and diesel three-wheelers were 97.2, 102.1 and 105.2dB respectively. SPL of large-buses with turbo and normal engines were 95.0dB and 103.6dB respectively. Rank order of the vehicles according to LAmax level and SPL of engines was the same. LAmax of horns ranged from 100.1dB to 113.3dB. There was no relationship between the category of vehicle and the LAmax of the horn. CONCLUSIONS AND RECOMMENDATIONS: Diesel three-wheelers, two stroke petrol three-wheelers and large buses with normal engines are the noisiest vehicles while cars, jeeps and pickups were the least noisy vehicles in the city of Colombo. Prohibition of importation of diesel three-wheelers and large busses with normal engines will help to make the county less noisy.