The braking visibility distance is the minimum distance necessary for a vehicle to stop before reaching a fixed obstacle that appears suddenly on the road, and it is the sum of the perception-reaction distance plus the braking distance. The PNE Point of No Escape) is the distance to the place in which a driver of a vehicle must begin the braking maneuver to avoid colliding with another in a vehicular crossing. The book includes a software that makes it easier to calculate this distance (braking visibility distance).