Design Guidelines and Conditions that Warrant Deployment of Fully Actuated Coordination

Most signal timing design documents focus on critical parameters such as cycle, offset, and splits but provide little guidance on other coordination parameters. The choice of settings for those parameters consequently is based on opinion more often than on quantitative results. The force-off mode (fixed or floating) and the use of fully actuated coordination (or early yield) are two such parameters. In this study, software-in-the-loop simulation was carried out to evaluate the impact of these two design parameters on coordinated system performance. Four alternative volume scenarios were simulated to explore a variety of conditions based on varying demand for the main street and side street movements. When side street volume approaches capacity, operational benefits arise for the associated phases, particularly when main street volumes are below capacity. Some modest improvements in individual movement average delays are observed even when the main street volumes are also near capacity. Fixed force-off and fully actuated coordination reduce the delay of noncoordinated phases. Coordinated phase delay and arterial travel times are not affected. The recommendation is made for coordinated intersection designs to feature detection on all phases and to be configured for fixed force-offs and fully actuated coordination.