Exploring impacts of countdown timers on traffic operations and driver behavior at a signalized intersection in Bangkok

This study aims to explore the impact of the countdown timer at various stages of the signal cycle, using two approaches: a traffic analysis and a public opinion survey conducted in Bangkok. The traffic analysis made a comparison of traffic characteristics during an off-peak day time at a selected intersection when the countdown timer was in operation against when it was switched off. A public opinion survey was conducted on more than 300 local regular drivers who are familiar with the technology. It was found that the presence of the countdown timers at the intersection would help to reduce the start-up lost time at the beginning of the green phase by 22%, and reduce the number of red-light violations during the beginning of the red phase by 50%. Furthermore, more than half of the local drivers reported that the timers help to relieve the frustration caused by stopping for uncertain amounts of time during the red phase. However, the timer was also found to slightly reduce the saturation flow rate during the green phase. The public opinion survey showed that the majority of the local drivers were favorable towards the system, and would support the municipality installing such devices on the street network.