THE BLACK BOX SOLUTION
Today's Accident Reconstruction engineer has a variety of tools to assist in determining the complex forces and motions involved when two vehicles collide. Most involve the input of vehicle, impact and rest position data, which are used in Conservation of Momentum analyses to determine the pre-impact speed. At the same time, vehicle crush and stiffness data is entered so that the deformation energy can be compared with the energy loss computed from the momentum analysis. The most popular of these are the CRASH and SMAC programs and their derivatives.
Engineering Dynamics Co., which currently supply a number of popular packages, are currently marketing the next generation of accident reconstruction programs. Termed "HVE" or Human-Vehicle-Environment, the system is based on 3D wire frame models for the specific vehicle, occupant, and driving environment. The required computer power is magnitudes larger than that currently necessary. The recommended Silicon Graphics workstations, with software and training, will likely have a cost in the $50,000 U.S. range. When not in use, they could be working on the animation for Jurassic Park II! Even with this technology, the analyses may be somewhat limited in that timing and amounts of driver steering, braking, etc., can be only assumed. Most of the vehicle parameters are estimates based on testing of other vehicles. The occupant data is based on "average" occupants. The net result is that most accident reconstruction firms will likely not be persuaded to immediately make the leap to these second generation systems.
As this evolution takes place, another revolution is quietly unfolding. Vehicle electronics! Vehicle acceleration is not measured to determine airbag inflation. Vehicle steering, yaw rates, and throttle may soon be measured to control vehicle anti-yaw systems. Vehicle brake actuation and wheel slip is measured to control anti-lock brake systems. Occupant position, seatbelt usage, and belt force may soon be measured to control airbag deployment and "smart" seatbelt systems.
Vehicle headlight configuration (on, high or low or burnt out), turn signals, hazard signals, ignition, horn, door and trunk opening are all currently monitored in most vehicles. Vehicle radar systesms to monitor traffic ahead, impending impacts, and driver blind spots are currently under development. Driver "alertness" monitors are currently being investigated to detect when a driver falls asleep. In short, most of the parameters of interest to the accident reconstruction engineer are or may soon be monitored by vehicle electronics.
What if these were recorded and the data saved in a little box and the box painted black? What if every vehicle on the road had a similar tamper proof unit? These "black box" systems are currently the norm for aircraft, and are being developed in Europe for automotive applications. The units are designed to record the relevant data for the 45 seconds prior, and 15 seconds after what is defined as an accident (high acceleration rate). When no accident occurs, the new data constantly overwrites the old so that only the most recent 60 seconds is saved. After an accident occurs, the unit can be removed from the vehicle, and the data down loaded to a computer.
The currently available black box systems can monitor most of the relevant parameters, however, they do a poor job of integrating with the existing vehicle sensors. The related software is in its infancy, and needs further development as well as universal acceptance to evolve further. Ethical and Charter of Rights considerations, potentially an enormous obstacle, have not been addressed.
The benefits include reduced accident reconstruction costs, reduced legal costs, with more accurate results. The units allow reconstruction to occur where there is very little other physical or witness evidence. Reduced product liability costs for manufacturers, and a positive influence on driver behaviour may be other benefits. The units will likely be advantageous to the "good" drivers at the expense of the "bad" drivers.
Only time will tell whether these systems will gain acceptance. It is likely that the benefits will outweigh the negatives, and at some point in the future accident reconstruction will involve downloading the black box data, measuring the site, and outputting the results. All "sides" will agree from the onset. The speeding vehicle will be shown to be speeding and the stopped vehicle stopped.
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Walters Forensic Engineering | 277 Wellington
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