The researchers conducted a detailed investigation to evaluate the effect of traffic lights on the congestion taking into consideration the weather conditions. After collecting enough data and performing computer simulations, the team concluded that adjusting the signals at intersections can reduce delays by up to 20% in bad weather conditions.
Until today, traffic lights timing is adjusting by analyzing factors such as traffic volume and velocity in order to enable the optimal vehicle flow through intersections. However, those analyses assume regular weather conditions. “The problem is that those parameters all assume normal weather conditions. In the winter, if the road surface is covered with snow and ice and visibility is poor, the numbers are not the same,” Dr. Liping Fu, Professor in the Department of Civil and Environmental Engineering and Director of the Innovative Transportation System Solutions (iTSS) Lab at the University of Waterloo, stated.
The study included analyzing data obtained by a busy intersection near the campus of the University. Scientists tried to evaluate how the behavior of drivers alters during extreme weather conditions by examining factors including speed and stopping distance, among others. They analyzed 2 cases: a single intersection and 4 co-ordinated intersection road. The team also implemented moderations to improve safety including the extension of yellow light interval as motorists drive slower and more time is required to stop.
The results showed that alterations to increase safety and reduce delays cancelled each other out at a single intersection. However, even when applying safety measures, delays decreased by up to 20% in the 4 co-ordinated road.
According to Prof. Fu, some cities are already utilizing computerized signal systems to modify the traffic lights timing when the weather conditions alter. In the future, video technology and Artificial Intelligence can be utilized to conduct such modifications based on weather and traffic congestion in real time. “Ultimately we want signal controls so smart that they actually change themselves in real time based on what is happening in the road network for any reason,” Prof. Fu stated.