Estimating Emission Impact of Traffic Flow Operation with Dual-Loop Data

Abstract

While many regional level studies have been reported, project level studies are limited because of lacking microscopic traffic parameters revealing transportation emission changes under varied real-world traffic operations. This paper presents a Vehicle Specific Power (VSP) based model for estimating the emission impact of traffic flow over dual-loop monitoring stations in highways. An innovative algorithm is developed to generate traffic volume, vehicle composition and operating mode distribution from dual-loop data. Those parameters are contributing variables in the VSP based emission model and their accuracy is tested using video-based ground-truth data. A case study using the presented model on an I-71 expressway section shows that traffic flow state is a function of operating mode distribution, traffic volume and vehicle composition. These three traffic parameters dominate mobile source emissions along the specific road section studied. The VSP based model provides a linkage between traffic operation and vehicle emission impact analysis. The presented methodology makes it possible for project level mobile source emission impact studies to be performed using the prevailing microscopic real-world traffic data.