The issue of using countdown timers at intersections with traffic lights: A literature review

The article presents an overview of the literature in the field of research on countdown timers used as auxiliary devices in traffic light systems. Although such devices are very popular especially in Asian countries, they are considered controversial in a number of respects. The aim of this paper was to study the available evidence referring to the effectiveness of digital countdown timers in improving the safety and operational efficiency of intersections with traffic lights. Based on the literature review, it has been proved that countdown timers are very useful, improve comfort, safety and smoothness of traffic in the opinion of drivers. The results of research carried out by various authors are consistent in this respect. However, while assessing the impact of countdown timers on intersection capacity and road safety, the results of studies are not consistent and often contradictory. The biggest discrepancies were observed when assessing the effect of countdown timers on road safety in the context of entries at red and yellow light as well as untimely entries. The tendency of the drivers to accelerate in the final phase of the green signal may increase the risk of collisions on the one hand and on the other hand, it improves the intersection capacity. There is a lack of information on determining the real impact of countdown timers on the number of collisions in the presented literature review. Many of the discrepancies in the conclusions can be influenced by various factors, among which cultural conditions cannot be forgotten.