Methods for predicting noise in the vicinity of signalized intersections

To accurately estimate the noise at a signalized intersection, it is necessary to precisely reproduce the traffic volume, signal cycle and traffic noise for each vehicle behavior and driving state. Precise reproduction requires considerable effort, such as continuous calculations of vehicles and the setting of parameters such as engine speed, engine load and velocity. A simple method that involves using A-weighted sound power levels (L-WA) under nonsteady running conditions has already been proposed for estimating noise at signalized intersections in a previous paper. In this study, the authors developed two simple methods for predicting noise in which the effects of acceleration and deceleration by signals is reflected. One method is based on a microsimulation traffic model, in which equivalent continuous A-weighted sound pressure levels (L-Aeq) is calculated by adding the noise of vehicles passing a green signal and the noise of vehicles decelerating and stopping at a red signal then accelerating when the signal turns green. The other method is even simpler and involves the assumption that an intersection zone is an unsteady running section and that L-WA for a nonsteady running section is larger than that for a steady running section. Noise predicting by the three simple methods is compared with actual measurements at 10 sites. The two new methods had slightly improved accuracy relative to the measured results.