A Before-and-After Study of a Collision Risk Detecting and Warning System on Local Roads

Figure 6

Three-step method to identify risky situations. (a) Two objects are excluded as the distances from object A exceed thirty meters. (b) Intersecting points (blue dots) are excluded since the point is outside local roads or the time difference in arrival times to the point exceeds two seconds. (c) If reachable areas overlap three times consecutively, the situation is considered to be a collision risk, and TTC is defined as the time when the two reachable areas first overlap.