About the research
The determination of the level-of-service (LOS) at signalized intersections is an important activity for decision-making in the allocation of resources for managing public roads, estimating the impact of new developments, and designing signal timing plans. The Highway Capacity Manual (HCM) methodology for signalized intersections is the most widely used method of estimating the LOS. The core of this methodology is a delay equation that takes as its inputs the demand volumes for various movements at an intersection, the signal timing, and other parameters related to the configuration of the intersection.
For right-turn movements, the current HCM methodology instructs users to obtain field measurements of the right-turn-on-red (RTOR) flow rate or else to assume that all of the right-turning vehicles execute the movement during the green interval. A consequence of this is that the estimated delay for the right-turn movement is likely overestimated. Other estimated quantities related to characteristics of the right-turn movement, such as the pedestrian delay, are also likely to be inaccurate. Furthermore, the scenario of dual right-turn lanes has not received much attention in previous studies.
The main products of this research are the models, which are documented in the report and in this summary. In addition, a practitioner guide was developed that contains documentation of the models along with a spreadsheet tool to provide sample calculations. Additionally, the RTOR volume calculations have been integrated into the HCM Computational Engine. The practitioner guide also includes a synthesis of guidance on whether to permit RTOR at a given location. In addition, during the course of this research a survey was distributed to develop an understanding of current practice with regard to RTOR. The survey results are presented in this report.