Assessment of changes in environmental pollution by road noise using a scalar measure

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The article addresses the issue of assessing the impact of road rebuilding on traffic noise pollution. To assess noise hazards, parameters expressed on the decibel scale were used, and a new measure was proposed - a scalar reference that compares the sound level value to the recommended threshold. This measure is based on Weber Fechner's law, which relates to human perception of changes in sound levels. It was derived through the decibel algebra applied to measurement results and is called the “coefficient of exceedance of the recommended sound level”. Its usefulness was verified by analyzing the results of measurements of traffic and noise parameters before and two years after the reconstruction of a section of the national road in Kielce. An assessment was made of traffic volume, vehicle speed, and road vehicle noise. The analysis evaluated the absolute values, variability and uncertainty of results obtained for the entire year, Fridays and Sundays. Significant differences in traffic parameter values were observed between the lanes entering and leaving the city on weekdays and weekends. The analysis showed a 28% increase in traffic volume following the road reconstruction. The current measure, which compares the difference in noise levels before and after the road reconstruction, indicates that while noise levels have decreased, they still exceed the normative values. For the same parameters, the median coefficient of exceedance decreased by approximately 17%, and the maximum coefficient of exceedance decreased by approximately 15%. The diagnostic usefulness of the coefficient of exceedance was further assessed using noise simulations based on the Cnossos-EU model. These simulations showed the high sensitivity of the proposed scalar noise measure to changes in vehicle speed and traffic volume. The simulations also indicated that to meet the Polish noise normative values, traffic volume would need to reduced by 50%, and the vehicle speed would need to be capped at 50 km/h. Additionally, the simulations suggested that even more stringent traffic restrictions would be necessary to meet the World Health Organization's noise recommendations.