RTOR is permitted as an effective approach to reduce delay at signalized intersections, especially where there is a high volume of right-turn movements. The conflicting intersection movements of motorized and nonmotorized users constitute a critical issue that affects signal operation and safety. A method is needed to estimate the RTOR flow volume and its effect on delays because current RTOR estimates are not reliable for planning- or operational-level applications. Gaps in the Highway Capacity Manual (HCM) method include (1) the lack of guidelines on whether RTOR should be implemented or not; (2) the current signal timing model that does not adequately reflect the true operational effects of RTOR; (3) no volume estimation model for right-turn delay; and (4) the pedestrian method that does not consider RTOR flow rate as an input nor does the existing RTOR guidance adequately consider nonmotorized users. As a result, agencies throughout the country have applied different RTOR techniques, which may lead to confusion. The development of an HCM method, therefore, will provide guidance on RTOR implementation and will assist agencies and practitioners by providing a consolidated body of knowledge on RTOR analysis.
Under NCHRP Project 03-136, “Evaluating the Performance of Right-Turn-On-Red Operation at Signalized Intersections (with Single and Dual Right-Turn Lanes),” Iowa State University was asked to (1) evaluate methods for evaluating RTOR at signalized intersections (right-turn configurations including shared, single, and dual right-turn lanes); (2) develop methods and tools that consider all modes and inform planning and operational decisions; and (3) provide potential modifications to standard references in the HCM, NCHRP Report 812: Traffic Signal Manual, and the Manual on Uniform Traffic Control Devices (MUTCD). The developed volume and capacity models enhance the state of the practice on RTOR design, support the HCM on RTOR volume estimation and site selection, and provide a better estimation of the delay due to RTOR movements. The output of volume estimation models developed in this study can be directly integrated into existing HCM analysis tools.
In addition to NCHRP Research Report 1068, several deliverables that support its implementation are available on the National Academies Press website (nap.nationalacademies.org) by searching on NCHRP Research Report 1068: Right-Turn-on-Red Site Considerations and
Capacity Analysis: Practitioner’s Guide.
NCHRP Web-Only Document 368: Right-Turn-on-Red Operation at Signalized Intersections with Single and Dual Right-Turn Lanes: Evaluating Performance is available at: DOI: 10.17226/27264
NCHRP Research Report 1068: Right-Turn-on-Red Site Considerations and Capacity Analysis: Practitioner's Guide is available at: DOI: 10.17226/27131
