Evaluation of Continuous Green T-Intersections on Isolated Undersaturated Four-Lane Highways

The research presented in this paper analyzes the merging version of the continuous green T-intersection (CGT), an alternative intersection design–control that allows certain lanes along the main street to bypass three-way intersections, with side street traffic merging onto the main road. A comprehensive model encompassing 2,445 unique combinations of intersection conditions was run to compare the merging CGT with the standard three-way signalized intersection. The study demonstrated significant intersection improvements over conventional traffic signal timing. Specifically, significant benefits were observed for the merging CGT in total delay, fuel usage, and emissions of hydrocarbons, carbon monoxide, oxides of nitrogen, and carbon dioxide. In addition, an economic analysis showed significant user savings associated with CGT control. Because of higher traffic volumes on the main road than the side street, savings for vehicles on the main street outweighed any costs associated with side street traffic merging into the main street flow. These findings strongly support the decision to implement the merging CGT over standard three-way signalized intersection control. Before this work, no comprehensive model that considered the environmental and economic implications of any form of the CGT had been published, and no comprehensive model specifically focused on the merging version of the CGT.