Driver Response at Radar Speed Signs

Abstract

This research aims to study driver responses to radar speed signs (RSSs). It analyzes the behavior of drivers for their speed changes within a distance of 120 meters from the radar speed signs on Highway 32. The RSSs are installed in the outbound direction from Bangkok between Phra Nakhon Si Ayutthaya province and Sing Buri province. Vehicle speed data was extracted using an image processing method from the videos, which were recorded by drone. Then a statistical method was applied to summarize the results for individual speed in the areas before and after passing the radar speed signs. The results reveal that the average speed of vehicles departing from the first sign of each pair increases by around 3.0 - 36.5 kilometers per hour and exceeds the statutory speed. After departing the second radar speed signs of each pair, the average speed drops by 1.1 - 2.7 kilometers per hour to below the speed limit. Results from this study suggest that the installation of radar speed signs in a pair affects different driver response behaviors, which show positive responses in the second signs of each pair. The study results could be beneficial in determining a more effective way to apply radar speed signs for other locations.