A study was carried out to assess the effect of speed bumps on road traffic noise levels. Noise levels of different categories of vehicles were measured before and after speed bumps. Vehicles were categorized as passenger cars, passenger vans, three wheelers, motorcycles, and lorries. Depending on the vehicle category, the maximum noise level varied between 71 and 80 dB (A) under uninterrupted traffic conditions. The maximum noise level increased by over 5 dB (A) due to speed bumps for lorries and three wheelers. The results indicated that there is a considerable effect on the noise levels at a short distance from the speed bump perhaps due to the action taken by drivers to increase the speed of the vehicles. The equivalent noise level at 20 m from the speed bump was found to be on average 1.2 dB (A) higher than at the speed bump. The LAeq values at 80 m after the speed bumps were found to be similar to the average noise level at the speed bump. Since speed bumps are often placed near schools and other public places, the noise impact should be taken into consideration when planning speed bumps.
Keywords: Road noise; Environment; Motor ways; Vehicular traffic