Comparing traffic-noise model accuracy using state-specific emission data

In September 1999, the writers began a study for the Arizona Department of Transportation to develop Arizona-specific Reference Energy Mean Emission L evels. This study was conducted to determine if the noise emission characte ristics of Arizona highway vehicles are statistically different from those contained in the national database used in the Federal Highway Administrati on's traffic noise model (TNM). The findings of the study confirmed statist ical differences. The component of the study reported in this paper relates to the effects of those differences on equivalent noise levels predicted b y the current model program, STAMINA 2.0/OPTIMA, and by TNM. Results show a n average decrease in overprediction by STAMINA 2.0/OPTIMA from 3.2 to 1.1 dBA. For TNM, the average decrease in overprediction was from 4.3 to 3.0 dB A. These improvements in noise prediction accuracy have major implications for environmental planning, especially in urban areas.