Suwajchai Paoprayoon, Prungchan Wongwises, and Sorawit Narupiti

pp. 535 - 548

Abstract

This research aims at modeling interrupted flow traffic noise at a signalized intersection. The models
are mathematically derived by applying the inverse square law of sound pressure incorporating with theories
of traffic flow at an intersection. The traffic flow theories utilized for developing the model consist of characteristics of individual vehicle motion at intersection, shock wave model, and queuing analysis. The model
formulation is divided into two different approaches and takes into account of all regimes of vehicle movement while traversing an intersection (i.e. idling, decelerating, accelerating, and cruising conditions). The
first approach assumes a constant acceleration/deceleration rate for each type of vehicle. Another applies
inconstant acceleration/deceleration which comes from speed-distance relationship. The final models are
expressed in L_Aeq (1 hr).
Eventually, the developed models are validated by collecting equivalent continuous noise level in
1 min as well as traffic parameters (i.e. red time, number of vehicle in the queue, queue length, time of
queue dissipation, and final cruise speed) from fifteen vehicle platoons. The noise levels predicted from the
developed models are compared with the measured ones. The results show that the inconstant acceleration model gives the predicted levels closer to the measured ones than constant acceleration model. The error of
inconstant acceleration model ranges from 0.1-3.9 dB(A) with the average value of 2 dB(A) overestimated
and that of constant acceleration model ranges from 1.8-6.5 dB(A) with the average value of 3 dB(A) underestimated. It might be concluded that movement characteristic of vehicle is an important factor that
apparently affects the accuracy of traffic noise prediction at an intersection.