Challenges to evaluation of CO2 impacts of intelligent transportation systems

ITS systems can help reduce CO
₂
emissions in three different ways, which need to be evaluated using different modeling paradigms. The ITS systems that reduce demand for vehicle travel should be analyzed using regional transportation planning models that explicitly represent modal choice and pricing sensitivity of travel choices. The ITS systems that improve vehicle operating efficiency should be evaluated using microscopic models of the effects on individual vehicles, and the results should be extrapolated to the system level based on travel statistics. ITS systems that improve infrastructure efficiency will generally require use of microscopic traffic simulation models, combined with new data representing how driver behavior is influenced by these systems in practice. Finally, concerns about latent and induced demand effects of transportation improvements need to be addressed with new research that reveals the real elasticities of travel demand.