“BLACK BOXES” FOR TRACTOR TRAILERS
Advanced Crash Data Recorders
In this modern age and rapid technological changes, there are many more sources of critical, objective information available on commercial vehicles. Large trucks, common carriers, and even buses are now being equipped with operation recorders just like commercial aircraft. As the cost of this equipment decreases, there will come a day when such information will be available in all vehicles, even private automobiles. However, given the overall long life of a commercial tractor trailer rig, we still see a lot of older trucks without this important source of data.
Most truck engines built in the last ten years contain an Electronic Control Module which records averages speed, rpm, time spent in gear, etc. In addition, these modules will record data from hard braking and crash events, allowing an investigating engineer to determine the speed, braking and shifting actions taken in the seconds before and during a crash. This hard evidence can prove invaluable in confirming or refuting a trucker’s testimony who claims he was not speeding or driving recklessly. The historical data may also be able to show patterns of excess speed and can even be compared to the listed driving hours on service records to see if the times for stops match up.
Volvo, Caterpillar and other manufacturers have all had Electronic Control Modules on their engines since the early 1990’s. Trucks with Detroit Diesel engines manufactured after December 1997 will have collision reconstruction information available. And, Mercedes-Benz bought Detroit Diesel in 2003 which means their trucks will have the same data available after then. Once you determine if a particular truck has ECM, the next question is how much and what type of information is available? In the Detroit power units after 1998, there are generally two types of events recorded: a “hard brake” record and a “last stop” record. The hard brake record is activated when they tractor trailer engages its brakes and has a loss of over 7 mph of speed in one second. In that scenario, the ECM records one minute of data before and 15 seconds of data after the event. A last stop record is made when the tractor comes to a stop but it overwrites if the tractor begins to move again. Both events will record data including: MPH, RPM, Braking, Clutch, Cruise Control, Throttle and Engine Load.
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