Cyclists' adaptation to a countdown timer to green traffic light: A before-after field study

Countdown timers (CDTs) for pedestrians and cars have been shown to produce various effects, including improved efficiency and decreased safety. This study aimed to explore adaptive behaviours of cyclists towards a CDT to green traffic light, conducted as a before-after study in real traffic. Cyclists adapted to the CDT by searching for and using the information that it provided, mainly in terms of speed adaptation and glance behaviour. Start-up delays were reduced but there is a concern that red light violations could increase. There might be undesirable effects on crucial information intake in cases where the CDT was used not as a complement but as a substitute for the traffic light. The results essentially indicate that cyclists use the information provided by the CDT for their own efficiency, rather than for rule-based safety.