Reliability of Dynamap traffic noise prediction

Dynamap (DYNamic Acoustic MAPping) is an European Life project whose main scope is to implement “real-time” acoustic maps in a district of the city of Milan. Dynamap is based on the idea of finding a suitable sets of roads displaying similar traffic noise behavior so that one can group them together into single noise maps. Twenty-four monitoring sensors have been installed permanently in appropriate locations within the pilot zone (District 9) to obtain six dynamic noise maps. The project has come to its “Test and Fault Analysis” phase. A set of new traffic noise and traffic flow measurements have been recorded to shed light on the reliability of Dynamap prediction. Besides the expected error due to statistical fluctuations of traffic noise, our preliminary analysis show a systematic error inherent to the adopted traffic flow model, which is an essential ingredient of the whole approach. By correlating the traffic noise prediction error to the one due to the traffic flow model, we succeed in improving the Dynamap prediction thus limiting the overall error to within about 3 dB. We suggest that Dynamap scheme can be applied to large urban conglomerates in general, thus becoming a useful tool for monitoring traffic noise accurately and efficiently in large cities.