Modeling Eco-Routing and Congestion Zone Impacts on Vehicular CO2 Emissions in Washington, D.C.

Abstract

Mitigating vehicular carbon emissions remains a critical focus for efforts at combatting climate change. Using the Washington, D.C. area as a case study, this paper investigates potential reductions in vehicular carbon emissions through the complete adoption of eco-routing—the selection of vehicle paths that optimize for fuel consumption rather than travel time. Additionally, we examine the environmental and travel-time impacts of implementing a congestion pricing zone in the center of Washington, D.C. Vehicles were simulated using the Simulation of Urban MObility (SUMO) platform to analyze the effects of these traffic interventions on vehicular carbon emissions and average travel times in the Washington, D.C. area. Analysis of 480 simulations revealed that eco-routing reduced CO2 emissions by up to 23% during peak times in comparison to time-optimized routing, but also increased average trip times by 12-18% in comparison. Furthermore, testing indicated that the addition of a congestion zone policy in the D.C. Central Business District can reduce carbon emissions by up to 7.4% during peak times. However, the congestion zone was only effective during busy hours, and combining the congestion zone with eco-routing eliminated the zone's benefit–slightly increasing emissions relative to eco-routing alone, as both interventions divert vehicles onto smaller roads and interfere when applied together. Our findings underscore that carbon-optimized routing and traffic policy interventions can achieve substantial reductions in vehicular CO2 emissions within urban networks, at the expense of slightly longer travel times.