Study of Traffic Noise in Urban Street Canyons of Bengaluru City

In urban street canyons, external noise environment is a critical restriction to the opening of building windows for natural ventilation. The high external noise intensities are often used to substantiate the utilization of air conditioning systems in residential and commercial buildings. Therefore, a systematic method of examining the noise levels in urban street canyons is essential if the potential for natural ventilation is to be estimated. The noise levels and natural ventilation in urban street canyons depend on many aspects such as existing street dimensions, height of buildings and traffic density. A study has been carried out in a street to examine the variation in noise levels vertically in order to provide technical inputs on natural ventilation potential in urban street canyons. In this study, a number of noise measurements were made in urban street canyons of Bengaluru City, in residential and commercial areas with respect to aspect ratio (height of building/street width) changing from 1.0 to 4.0. With the help of measured data, a statistical model was developed. A linear regression analysis has been used. The model can be used to predict variation of noise level in vertical direction in urban street canyons. The variation of noise level is found to be a function of street width and height of a building above the street level, but the highest level of reduction is almost entirely a function of the aspect ratio. The rate of attenuation of foreground noise (L₁₀) is greater than the background noise (L₉₀) with height.