The effects of time-reminder strategies on drivers’ perception of waiting time at signalized intersections

Signal indications and waiting times are displayed to drivers at signalized intersections using exact countdown timers or approximate visual timers, such as sandglasses. Although previous research has examined traffic operations and safety at intersections with and without countdown timers, drivers’ perceptions of waiting time under these strategies remain unclear. This paper examines whether perceived waiting time (PWT) matches actual waiting time (AWT), compares PWT across timer types, and identifies factors influencing over- or under-perception through linear regression. Roadside interviews with 300 Iranian drivers showed that average PWT was about 20% lower than AWT at countdown-timer intersections. Conversely, PWT was 17% higher than AWT where no timer was present and 13% higher where a sandglass was used. Countdown timers reduced variation in perceived waiting time and eliminated outlier estimates. These observations suggest that time displays can mitigate waiting-time overestimation, but real-time information is necessary; near-real-time information may not reduce general over-perception.