Noise levels of vehicles in the city of Colombo

Abstract

INTRODUCTION AND OBJECTIVES: 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 types of vehicles. Objective of this study was to determine the noise emitted by 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: Diesel three-wheelers recorded the highest SPL (105.2dB) while cars recorded the lowest SPL (80.2dB). 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. Ranking order of the LAmax level of engines were the same as for SPLs. LAmax of horns ranged from 100.1dB to 113.3dB. Maximum permissible noise level in a municipal council area during day time is 63dB. CONCLUSIONS: Diesel three-wheelers, two stroke petrol three-wheelers and large buses with normal engines are the noisiest vehicles in the city of Colombo