Development of a relation between traffic variables and environmental noise descriptors for four-lane National Highways

Abstract

In India, transportation sector is quickly expanding. The heterogeneity of traffic plays a vital role in shaping noise ambience in vicinity of highways. This study aims to evaluate the factors that contribute to traffic noise along four-lane divided National Highways. Data were collected at 4 locations with free-flowing traffic on the National Highway 334 in India. The parameters included traffic noise levels, classified traffic volumes, vehicular speed, and geometry of highway cross-section. Traffic volume and composition were captured using videography, while traffic speed was measured using radar gun. Single octave spectral characteristics of the traffic noise were measured using a multi-channel noise spectrum analyser. The data was sampled at 15 minutes intervals and measurements carried out for 3-hour duration during peak and off-peak periods weekdays and weekends. Noise descriptors such as equivalent noise level (Leq), 10 percentile sound level (L10), 50 percentile sound level (L50), 90 percentile sound level (L90) were estimated from the measured data. Effect of traffic characteristics on the traffic noise levels was established through regression analysis. The study concludes that traffic volume, percentage of heavy vehicles, and traffic speed are the major factors influencing noise levels.