Urban road noise: The contribution of pavement discontinuities

The purpose of this work consists in the evaluation of noise generated by vehicles moving over single irregularities present on the road surface by means of acoustic measurements made with a sound level meter. Ten macroscopic irregularities, considered as representative of the most common types (manhole covers, holes, tramway tracks etc.), were chosen for this study. The most representative dimensions of the chosen irregularities were plotted by using an original device for profile measurement. Acoustic measurements were taken using the same vehicle following the indication reported in UNI 11819/1: “Statistical pass by method”. The test vehicle passed over each irregularity twice at three different speeds (40, 50, 60Km/h). Two further transits were made at the same speeds, over the same type of surface, this time intact, close to the irregularities in this study. The purpose of this was to evaluate the increase in noise caused by the passage of the test vehicle over these irregularities. The characteristic acoustic parameters were examined for each measurement in time domain (time history of sound pressure level, and its maximum value). The results of this work showed interesting correlations between vehicle speed, geometric characteristics of irregularities, and road noise.