Capacity Analysis and Safety Assessment of Unsignalized Intersection Using Conflict Technique

Intersections pose special safety concerns because of the high probability of critical conflicts resulting from unsafe driver actions and maneuvers. The absence of movement priorities, lack of lane discipline, forced entry by non-priority movements, etc., at unsignalized intersections violate the assumptions involved in capacity calculation. A key aspect of this study is to analyze conflicting flows at unsignalized intersections, which vary depending on site conditions and geometrical features in heterogeneous traffic environments and to estimate movement capacity at unsignalized intersections. At unsignalized intersections, vehicles from different directions cross and turn simultaneously, resulting in severe vehicle-vehicle conflicts. Thus, traffic safety is an important aspect to be evaluated at unsignalized intersections. The study also aims at conducting a safety assessment at unsignalized intersections using the microsimulation model (VISSIM) coupled with the Surrogate Safety Assessment Model (SSAM). The study found that SSAM is adaptable to intersections of varying geometry and serving heterogeneous traffic.