Specifications include, but are not limited to: The Federal Highway Administration (FHWA) Traffic Signal Timing Manual (STM) has been the most widely accepted reference across the traffic signal timing field. Since the release of the second edition in 2015 (STMv2), there have been significant advances in signal timing research and practices, and several NCHRP and FHWA initiatives have been implemented. · NCHRP Project 03-125, “Evaluation of Change and Clearance Intervals Prior to the Flashing Yellow Permissive Left-Turn Indication” evaluates change and clearance intervals prior to flashing yellow arrow (FYA). · NCHRP Research Report 954: Performance-Based Management of Traffic Signals compiles the best available information on automated traffic signal performance measures and management strategies for traffic signal operations. · NCHRP Web-only Document 284: Decision-Making Guide for Traffic Signal Phasing provides guideline for traffic signal phasing. · NCHRP Research Report 969: Traffic Signal Control Strategies for Pedestrians and Bicyclists addresses the multimodal signal timing for nonmotorized users. · NCHRP Research Report 959: Diverging Diamond Interchange Information Guide, second edition, presents a comprehensive guide to the design and operation of diverging diamond interchanges (DDI). · NCHRP Project 03-136, “Evaluating the Performance of Right-Turn-On-Red Operation at Signalized Intersections” addresses performance of right-turn-on-red operations. · Traffic Signal Management Plan Guidance Document (FHWA-HOP-15-038). · Traffic Signal Management and Capability Maturity Framework (CMF, FHWA-HOP-16-028). · Promotion of basic service model concept (FHWA-HOP-09-055) highlighting the need to scale equipment and operations based on agency staff. Major industry references and standards have been updated with new computational methods and operational practices incorporated. · Highway Capacity Manual, sixth edition, (HCM6-2016) provides updated procedures for computing the capacity of various highway facilities including signalized intersections. · NEMA-TS2-2016 Standard incorporates FYA feature, as well as associated configuration and other related information. · NTCIP 1202 v03A-2019 has updated clauses on FYA and other corrections related to signal operations. New technological trends are emerging, such as applying new computational approaches to the signal timing process, developing signal timing plans using novel datasets, and implementing new signal timing paradigms for connected and autonomous vehicles (CAV) and connected intersections. The traffic signal timing community has highlighted important topics to be addressed in a new version of the STM, including the signal timing of unconventional intersection geometries; advanced bicycle, pedestrian, and transit signal timing; cybersecurity risks tied to the signal timing procedures; and innovative signal timing design using standards-based controller features. The STM has served as a primary reference for the FHWA Traffic Signal Timing Concepts course. The course presents a signal timing workflow that starts with goals, explores context with a focus on vehicle flow, and then selects strategies and tactics that support attainment of objectives. It is envisioned that an update to the STM’s structure could better support this workflow, inclusive of performance measurement to validate objectives and demonstrate progress towards goals and enhance the coverage of pedestrians, bicycles, transit, Complete Streets, safety, and equity. The update should consider how signal timing fits in with the overall traffic signal program, as other elements within the program (e.g., maintenance, equipment health) may directly impact the success of signal timing activities. OBJECTIVE The objective of this research is to provide guidance on utilizing up-to-date effective practices and research outcomes that have been successfully implemented after STMv2. At the minimum, the research shall: Support an objectives-oriented, actively managed traffic signal timing process that starts with goals, considers context, supports the implementation of strategies and tactics, and addresses evaluation of signal timing design outcomes, Address signal timing strategies for various intersection and roadway network users, including nonmotorized users and transit vehicles, Incorporate existing research and effective practices to expand the coverage of over-saturated/congested conditions, and Describe use cases for advanced/innovative controller features, such as peer-to-peer communication, custom logic, etc.
