Prediction of accuracy of temporal sampling applied to non-urban road traffic noise

The legislation on road traffic noise often requires that acoustic descriptors be determined on a medium or long term. However, such a duration is not feasible for attended monitoring, and therefore, temporal samplings are often applied to save time and resources. However, the values of the noise descriptors estimated by those measured at the sampling times are affected by uncertainty, the amount of which depends on the ratio between the total measurement time and that of the estimate, as well as on the variability of the noise immission at the measurement point.This paper describes the results obtained from the statistical analysis performed on a large set of acoustic data collected at 80 sites along the non-urban road network in the Lombardia region (Italy). The aim of the analysis is to determine the accuracy of two procedures to estimate: i) the daytime (06 to 22 h) A-weighted equivalent level LAeqd and the nighttime (22 to 06 h) A-weighted equivalent level LAeqn from the hourly A-weighted equivalent level LAeqh; and ii) the LAeqh level from the LAeqt measured continuously for a shorter time interval t. The proposed procedures enable to predict the accuracy of both the above estimates; the second one, that is the LAeqh level from the LAeqt, resulted to be greater with increasing of hourly traffic flow and measurement time. Example of the applications of the two procedures is also described