ANALYSING STREET TRAFFIC NOISE POLLUTION IN THE CITY OF YAZD

A model is demonstrated that describes street traffic-induced noise pollution in 2008 in Yazd, Iran. Sound levels were measured using a Bruel and Kjaer-2260 sound level meter on 10 streets across the city over this period during the morning rush hour and different vehicle types were counted simultaneously at various sampling points. Geographical Information System was used to generate, store and retrieve the spatial data and map the sound levels using an interpolation technique. The minimum and maximum sound levels appeared to be 70.9 dBA and 80.7 dBA, respectively and these values were above the national legislated norm. Cars and motorcycles were the most commonly used vehicle type in the city, comprising 61.2% and 23.7 % of the total traffic volume, respectively. These data were followed by trucks, buses and bicycles. A number of parameters which were assumed to impact on noise pollution were collected and considered, including geographical position, elevation, the distance to the nearest intersection, street geometry and the numbers of vehicles according to class. The modelling demonstrated that there is a significant relationship between the average sound level and traffic flow (R(2) = 0.5). The results showed that although street traffichas increased between 2002 and 2008, the sound levels in the city decreased slightly and this has been attributed to advances in vehicle design.