Analysis of MOVES and CMEM for Evaluating the Emissions Impact of an Intersection Control Change

EPA’s Motor Vehicle Emission Simulator (MOVES) provides greater capability than the MOBILE emission models for estimating the impacts of traffic operational changes. EPA has proposed requiring the use of MOVES for conducting “project-level” analysis of PM and CO hot-spots. Local sustainability programs and federal grant program such as CMAQ reinforce the need for a consistent modeling system for estimating emissions from traffic operational changes. This research compares the emissions estimates from MOVES with those generated by the Comprehensive Modal Emissions Model (CMEM), developed under NCHRP 25-11. CMEM was developed to meet the need for an emissions modeling system responsive to traffic operational changes. CMEM integrates with existing microsimulation software packages that generate second-by-second speed/acceleration vehicle profiles (trajectories). The research developed a microsimulation test bed of a 3-leg intersection modeled as a pre-timed traffic signal and as a roundabout under 2 traffic volume scenarios. CMEM and MOVES output for CO and NOx (grams/hour) are evaluated. For NOx, results from CMEM are similar to those from MOVES when a detailed Link Drive Schedule is estimated from trajectory data using K-means clustering and LOESS scatter plot curve fitting. For CO, results from CMEM and MOVES are significantly discrepant over all modeling scenarios. Both CMEM and MOVES (utilizing Link Drive Schedules) estimate higher emissions for the roundabout when compared to the traffic signal. Sources of emissions differences between CMEM and MOVES are discussed and enhancements to facilitate linking MOVES to microsimulation models are proposed.