The National Academies

NCHRP 03-149 [Anticipated]

Signal Timing Manual: Development of the Third Edition

  Project Data
Source: Utah Department of Transportation
Funds: $750,000
Staff Responsibility: Zuxuan Deng
Fiscal Year: 2023

This project has been tentatively selected and a project statement (request for proposals) is expected to be available on this website. The problem statement below will be the starting point for a panel of experts to develop the project statement.

The Signal Timing Manual (STM) has been the most widely accepted reference across the signal timing field. Since the release of its second edition in 2015 (STMv2), there have been significant advances in signal timing research and practices. Several NCHRP and FHWA initiatives have been implemented, and major industry references such as Highway Capacity Manual, 6th edition (2016), Highway Capacity Manual, 7th edition (2022), NEMA-TS2 Standard Version 3.07 (2016), and NTCIP 1202 v03A (2019), have been updated incorporating new computational methods and operational practices. New technological trends have emerged, such as applying new computational approaches to the signal timing process, developing signal timing plans using novel datasets, and instrumenting new signal timing paradigm for connected and autonomous vehicles (CAV). The 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.

While the current STM edition has materially assisted traffic signal professionals, it was developed in the previous decade and is lacking coverage of the most up-to-date developments in the signal timing field. There is an urgent need to develop a new edition (STMv3) that incorporates outcomes of the latest NCHRP and FHWA initiatives that have advanced to successful implementation, and the latest updates of major industry references (e.g., NEMA-TS2, NTCIP 1202, HCM6 and HCM7); provides timely coverage of new technological trends applicable to the signal timing process; and addresses common interests of the community with added or updated topics.

The purpose of this research is to update the current STM, which will be a decade old by the time the STMv3 is published. The new edition will synthesize up-to-date best practices and research outcomes that have been successfully implemented after STMv2, provide proper coverage of technological trends applicable to the signal timing process, and complement existing STM structure with updated and new chapters addressing common interests of the signal timing community.

Potential topics to be covered include:

1. New technological trends relevant and applicable to the signal timing process, such as the usage of novel datasets for developing signal timing plans, new computational methods, and new signal timing paradigms for CAVs.
2. Cybersecurity in the signal timing process, and related policy implications.
3. Updated guidance and support systems to effectively manage, operate, and maintain traffic signals.
4. Updated guidelines on flashing yellow arrows and signal phasing. Multimodal signal timing and performance measures, including advanced treatments for bicycle, pedestrian, and transit signal timing. Best signal timing practice for divergent diamond interchanges, single-point urban interchanges, and unconventional arterial intersection designs. Performance measures about right-turn-on-red operations.
5. Enhancement of the current STM structure, providing proper details, references, guidelines, or illustrative examples. Candidate subjects include Dallas phasing, third-car detection for permissive/protected left turns, application of peer-to-peer communications and logic processors, innovative usage of overlaps, advanced detection logics, algorithmic details for typical transit signal priority, preemption, and transition logics.

Potential tasks may include: (1) conduct an up-to-date state-of-the-art review, and review purpose, objectives, target users, and target usage for the STM and identify major gaps in current STM edition; (2) identify subjects, updates, and additions; and (3) prepare training materials based on the new STM edition.

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