scope:

This report presents the current state-of-the-practice and provides the user with a broad overview of key considerations to determine yellow change and red clearance intervals for traffic signals and their application. The intent for this report is to reflect a thoughtful balance between sound engineering theory and practical application. The underlying assumptions presented in the report should yield reasonable times for the yellow change and red clearance intervals for traffic signals that allow the profession to balance those durations while enhancing intersection safety and maintaining reasonable traffic flow. The goal of the proposed recommended practice is to create a consensus methodology for calculating and evaluating traffic signal change intervals that can be uniformly and consistently implemented by transportation agencies. The scope of the report is limited to yellow change and red clearance intervals for vehicular movements at signalized intersections and does not address enforcement or pedestrian signals.