Performance Assessment on Noncoordinated Signalized Arterials and Guidelines for Signal Coordination

This paper introduces a probabilistic model for calculating the expected number of stops on non-coordinated arterials. The model can be applied to developing a practical guideline for determining when the signals in an arterial should be coordinated. The main assumption of the model is that the probability of making a stop is a function of the effective green to the cycle length ratio which also relates to the traffic volume and capacity. Various sources made recommendations in terms of the traffic volume, platoon dispersion, and signal spacing, concerning when a coordination plan should be implemented. However, none of them considered the number of stops as a factor. We propose a stop-based guideline using the probabilistic model, stating that an arterial should be coordinated if the number of stops exceeds 50%. An arterial does not need to be coordinated when the number of stops falls below 20%, and engineering judgment should apply between these two thresholds. A case study using a VISSIM simulation was conducted to validate the probabilistic model and the proposed guideline in order to test its practicality. The results confirmed that the probabilistic model is highly reliable in estimating the number of stops, thus the developed guideline proved to be practical in considering both the main street and side street performances.