Continuous flow intersections: A safety and environmental perspective

Continuous flow intersections (CFIs) were invented to improve traffic operations of conventional intersections that suffer severe congestion caused by heavy left-turn movements by eliminating the protected left-turn phase and thus increasing the intersection capacity and reducing the number of conflict points. However, since drivers in the USA are not familiar with the operations of CFIs, there is a need to evaluate CFIs in terms of driver behavior, safety, and operational efficiency. In addition, there is a need to quantify the environmental impacts associated with CFI operations. The research presented in this paper assesses the operation of CFIs by conducting before and after field and simulation evaluations. The study concludes that drivers are initially unfamiliar with the operational characteristics of CFIs. These problems are found to be temporary and are resolved once drivers become acquainted with the operation of CFIs. The simulation analysis demonstrates how the introduction of a CFI results in operational improvements, fuel savings, and vehicle emissions reductions at different total traffic demand levels and for varying left turn volumes. The study demonstrates that CFIs are more robust to fluctuations in overall intersection demand levels and the left turning volumes compared to conventional signalized intersection control.