Estimate potential traffic conflicts based on real traffic conditions. This function will focus on estimating both rear-end and crossing (i.e. right-angle) traffic conflicts. The rear-end conflicts include the same-direction conflicts from all approaches, and the crossing traffic conflicts mainly are the conflicts between through movement and conflicting left-turns. To estimate the potential conflicts, first we need to estimate vehicles’ trajectories using high-resolution data. With the trajectory data, we then apply the traffic conflict technique to estimate both types of traffic conflicts at intersections. The overall intersection safety can be evaluated based on a combination of the probability of two types of potential conflicts.

1、Rear-end Conflict Identification

A conflict can be identified by calculating the difference in projected distance travelled between two succeeding vehicles. If the projected distance traveled over a period of time for the leading vehicle is less than that of the following vehicle, then there is a rear-end conflict. All rear-end traffic conflicts counted for the major road (TH-55) only. Conflicts for the minor approaches were only considered during the crossing conflict stage.

1、Crossing conflicts

Crossing conflicts are determined by first splitting the intersection into 4 “Conflict Zones”. When two vehicles with crossing trajectories are projected to be in the same Conflict Zone at the same time, a crossing conflict is identified. The following figure shows how the conflict zones are split.