A Road Traffic Queueing Model Balancing Emissions and Cost

Abstract

This paper examines a highway system using a queueing theory model, with parameters estimated from realistic data. Preliminary results include estimation of key performance indicators such as throughput, mean number of vehicles, and emissions. The model identifies the optimal number of lanes and speed limit that minimizes the combined costs of road construction and traffic delays. Additionally, the study extends to include a second objective, which is minimizing carbon emissions. Our results, comparing the results of both objectives, demonstrate that emissions considerations can influence the design of highway systems, and lead to significantly higher costs. In order to explore the trade-offs between reducing costs and emissions, we analyze this resulting two-objective optimization through the characterization of Pareto-optimal (efficient) solutions and their application to realistic scenarios. We observe that significant cost saving can be achieved (e.g. 20%) if one allows a small increase in emissions (e.g. by 0.5%) over the level stipulated by the single-objective emission minimization model.