Start-Up Lost Time at Signals Using Countdown Timers

Level of Education of Students Involved

Undergraduate

Faculty Sponsor

Jay Grossman

College

College of Engineering (COE)

Discipline(s)

Civil Engineering

ORCID Identifier(s)

Leah Haman, 0000-0002-8136-8979; Lilli Goss-Peirce

Presentation Type

Oral Presentation

Symposium Date

Fall 4-24-2025

Abstract

Start-up lost time refers to the duration it takes for the first few vehicles in a queue to respond to a green light at a signalized intersection. This delay contributes to inefficiencies and impacts queuing, particularly at intersections that are operating at full capacity. We conducted a study to assess whether traffic signals equipped with a countdown timer for the green light significantly reduce start-up lost time. Utilizing video footage from signalized intersections in the Dominican Republic that feature a countdown timer, we measured the interval between the moment the light turned green and the time the first vehicle in each lane began to move. This timing will be compared to start-up lost times at signals in the United States without a countdown timer to determine the efficacy of countdown timers in decreasing total vehicle delay at signalized intersections.

Biographical Information about Author(s)

Lilli Goss-Peirce and Leah Haman are both senior Civil Engineering majors with an interest in traffic and transportation. After graduation, Lilli will join Strand Associates in their transportation department, and Leah will join Apex Engineering Group in their transportation department.

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