Currently, most cars on the roads are equipped with anti-lock braking systems. Therefore, brake tracks, which define the latest moment of reaction, are rarely found. The investigator thus lacks important information to calculate the initial speed prior to the collision.

Investigating boundary parameters serve as a source to draw conclusions on reactions prior to the collision. Depending on the location of the accident investigating the vision of the driver could shed light on the earliest moment when opponents could possibly first have spotted each other in order to conclude on the reaction. But there are many cases, which are difficult to judge. For example a pedestrian who comes from a side street towards a road on which a car approaches. The question is on what point of time the driver of the car will recognize the pedestrian as a potential danger, which will cause him to react. But there are only few tests on these signal positions.