Improving Traffic-Noise Model Insertion Loss Accuracy Based on Diffraction and Reflection Theories

Abstract

This paper investigates the physical mechanisms related to highway noise barrier insertion loss, and evaluates the accuracy of insertion loss of the existing traffic-noise model, TNM 2.5, compared to STAMINA 2.0 and field measurement data. To quantify the accuracy of either TNM or STAMINA, a new Highway Noise Prediction program, HNP 1.0, was developed. The findings of the study show that from the perspective of diffraction theories, STAMINA 2.0 and HNP 1.0 predict more accurate insertion loss than TNM 2.5 based on the measurement data, and TNM 2.5 over-predicts the insertion loss by approximately 3 dBA when compared with STAMINA 2.0. By applying the assumptions used in HNP 1.0, an average of 2.5 dBA reduction of insertion loss with TNM 2.5 can be achieved. These improvements in noise prediction accuracy of insertion loss have major implications for environmental planning.