Analysis of the effects of grade, weather conditions and trip type on driver behavior during the yellow interval

At signalized intersections, drivers make a stop/go decision during the yellow interval. In such situations, where a dilemma may occur, an incorrect decision can lead to red-light violations and, consequently, traffic accidents. The primary objective of this study is to understand the events occurring during the yellow interval at intersections, identify the factors influencing driver behavior, rule violations, and the causes of traffic accidents, and propose solutions. In this context, a new method was developed to achieve a low-cost approach and ensure the shared use of existing public resources. Using this method, parameters such as speed, position, TTI, acceleration, vehicle type, and lane information were rapidly and reliably determined for each vehicle. By utilizing these parameters, the yellow light dilemma was defined for Istanbul, and the effects of factors such as gradient, trip type, weather conditions, and vehicle type on driver behavior were analyzed. The study observed that drivers who decided to proceed at two intersections with different conditions had similar perceptions of the yellow light. It was determined that weather conditions, trip type, and vehicle type influence driver behavior, whereas negative gradients and speed make drivers less sensitive to other factors. Additionally, it was revealed that both the behavior in Type I dilemma zones and the boundaries of Type II dilemma zones differ significantly from the results found in the international literature.