Evaluation of the efficiency of traffic lights turning red in case of exceeding speed limit with previous panels indicating the speed

Abstract

A usual traffic calming measure (TCM) to reduce vehicle speed in urban areas is the traffic lights that turn red when a vehicle exceeds the speed limit. These traffic lights can detect if an approaching vehicle exceeds the speed limit and, if so, stop it by means of a red light. It is generally employed in interurban roads rather than in big cities, where the presence of traffic lights is common. In a rural road crossing a small village, they are deployed to reduce the risk of accidents to vulnerable road used when vehicles arriving at high speeds tend to conflict with pedestrians attempting to cross the road. The aim of this paper is to analyze the efficiency of this TCM, preceded by panels indicating the vehicles’ speed, by controlling the vehicles’ speed in the A-132 road that crosses through the village of Azazeta in the province of Álava/Araba (Spain). Different sequence of the TCMs can be found in each direction approaching the village; in A direction, warning traffic lights, the panel indicating the speed and the traffic light turning red; and in B direction, the panel, the warning traffic lights and the traffic lights turning red. However, similar results were obtained in both directions for average speeds and percentile 85 of the speed distribution at the traffic lights, and speed was reduced as motorists faced the TCMs. However, although average speed was below speed limit (50 km/h), the percentile 85 was over it, implying that more than 26% of drivers did not respect the red light. Moreover, after the traffic lights turning red, motorist speed up and higher values were measured at the midpoint of the urban segment, the place where pedestrians use to cross from one side of the village to the other one, although no pedestrian crosswalk is available.