Steven M. Schorr, P.E., President of DJS Associates ::::
Increasingly, the data available to review as part of a collision reconstruction includes video, sometimes obtained from nearby surveillance cameras, and sometimes acquired from the vehicles themselves.
Many commercial vehicles are equipped with event data recorders in the form of a camera that captures different views as the vehicle proceeds along. Depending on the equipment, the data is either recorded continuously, or the camera is manually activated by the operator, or recording is activated by a defined sudden deceleration threshold.
Recently, we were provided with a video from a truck which showed a passenger vehicle on the right shoulder with its flashers on and its hood up. The daytime video showed a pedestrian suddenly emerge from behind the raised hood of the vehicle on the shoulder, and moved directly into the path of the approaching truck. The pedestrian was struck by the right front/center of the truck. Although the conclusion as to how the collision occurred seemed obvious, we were tasked with evaluating the event from a collision reconstruction perspective, i.e., what were the factors that led to this event and, in this case, were there any additional causal factors other than the actions of the pedestrian.
The four factors in any pedestrian collision are the roadway, the vehicle, the vehicle operator, and the pedestrian. In this case, the roadway was straight and level thus allowing the truck operator to see the stopped vehicle on the shoulder from over 500 feet away. This sight distance was reciprocal so the pedestrian, had he looked around his stopped vehicle, could have seen the approaching truck for over 500 feet.
The truck itself was inspected and there were no mechanical issues with the vehicle that would have, in any manner, contributed to the collision event. The driver of the truck was properly licensed and reportedly performed the proper pre-trip inspections (consistent with the fact that the truck had no mechanical issues).
The frame-by-frame analysis of the video, obtained from the truck itself, showed that the approaching truck was traveling 5 miles per hour below the posted 45 miles per hour speed limit prior to, and at the time of the collision. It also showed that once the pedestrian appeared from behind the stopped vehicle, he was only visible for approximately 1.8 seconds. A typical daytime perception-plus-reaction time to an unexpected event is approximately 1.5 seconds. Including a length of time (approximately 0.5 seconds) for the air pressure to build up prior to any braking action being effective (i.e. brake delay), the data showed that the period of time the pedestrian was visible as a hazard was not sufficient for the truck operator to perceive, react, and avoid a collision.
The application of the “steer clear” rule was evaluated (i.e., vehicles are required to move left of stopped emergency vehicles). While almost all states have this “move over” rule, its application, per the Statues, is in the event of emergency personnel activities and not for disabled vehicles on a shoulder. While the truck operator was responsible to have been attentive of the stopped vehicle on the shoulder, because the pedestrian was visible for such a short period of time, even had the truck slowed down even more than it did as it approached, the actions of the pedestrian still created an unavoidable hazard.
Steven M. Schorr, P.E., President of DJS Associates, Inc. is a Collision Reconstruction Engineer and can be reached via email at experts@forensicDJS.com or via phone at 215-659-2010.