Institute for Transportation

About the research

Traffic signal controllers use yellow change and red clearance intervals at signalized intersections to alert drivers to impending changes in the right-of-way assignment between conflicting traffic movements. Determining appropriate change and clearance intervals (CCIs) is important at signalized intersections to ensure safe transfer of the right-of-way while minimizing lost time and therefore reducing intersection delay.

To improve documentation and consistent implementation of CCI calculation methods in State and local agencies, the Federal Highway Administration is leading the Traffic Signal Change and Clearance Interval Pooled Fund Study. The pooled fund study sponsored a phase I study to develop a synthesis of knowledge on CCIs. The phase I study included a literature review and an agency benchmarking plan to synthesize existing research and agency practices and identify research gaps. Based on the review findings, this synthesis report presents eight research studies and the data needs to execute the research. The eight research studies include proposed methods for determining the CCIs and the CCI performance assessment.

This project is a task order under the main FHWA-sponsored project DTFH61-16-D-00053, in which LEIDOS, Inc. is the Lead.