Observation-Based Study of Intersection Dilemma Zone Natures

Abstract

Yellow phase dilemma zone is dynamically distributed at high-speed signalized intersections because of varying driving behaviors in response to yellow indications. This article presents an observation-based study of the natures of dynamic dilemma zones. A case study was conducted at a high-speed intersection in Fairfield, Ohio. Time-based yellow-onset trajectories were obtained using the video-capture-based technique and then they were used to analyze three types of dynamic dilemma zone models: that is, Type I and II dilemma zones, and option zone. The results reveal that the contributing factors of Type I dilemma zone and option zone are not constant but dynamic at different speeds. Vehicle type has been proved a factor that significantly affects drivers’ stopping behavior. Drivers of trucks are more likely to make pass decisions than drivers of passenger vehicles. Cars, sport utility vehicles, vans, and light trucks have similar downstream boundaries of Type II dilemma zone whereas heavy trucks have the furthest upstream boundary of Type II dilemma zone. Finally, the comparison between the option zone and the Type II dilemma zone is analyzed using the sample data.