Driver Behavior and Traffic Stream Interactions at Unsignalized Intersections

Abstract

This paper investigates the quality of traffic service at intersections that are nominally “priority unsignalized” but operate with partial respect for control measures. The operation of such intersections with moderate traffic volumes is characterized by the use of delay and conflict measures. A simple simulation model reflecting driver behavior and traffic stream interactions is developed as a proof of this concept. Intersection performance with similar flow levels but under other types of control is evaluated and compared with observed measures, and trade-offs are identified. It is concluded that basic models that incorporate driver learning and impatience, aggressive driver attitudes, and modes of stream interaction different from simple gap acceptance are helpful in explaining traffic performance at intersections that have incomplete enforcement of priorities. The study also indicates that, although lack of control may result in lower delays at intersections for certain levels of traffic volumes where self-organization may be possible, such intersection performance reflects aggressive driving practices and potentially occurs at the expense of safety.