Vehicle Black Boxes – Data Limitations in Accident Reconstruction

damaged event data recorder

Ten years ago, MEA bought the first publicly available system for downloading the electronic crash data stored in black boxes in cars.  There was some nervous laughter when colleagues joked that accident reconstruction engineers would soon be out of business. We’re still going strong, and here’s why:

1. Crash data doesn’t answer all the questions. Fundamental concerns about the reliability and accuracy of the data need to be addressed by an expert; otherwise a judge may exclude the data from court. And even if reliability and accuracy can be guaranteed, crash data rarely answer all of the questions. For example, it might provide evidence of excessive speed, but it won’t tell you if speed contributed to the crash. Or, it might tell you that a driver was not wearing their seat belt, but not whether seat belt use would have prevented an injury. Like other sources of physical evidence, crash data needs to be interpreted by a properly qualified expert to have an impact in court.

2. The number of cars from which data can be downloaded is limited. A recent upgrade to our Bosch download equipment adds Toyota to the short list of vehicles (GM, Ford and Chrysler-Fiat) that we can get crash data from. But only newer cars and not all models are supported. While the addition of Toyota to our list is enough to get engineers excited, the bigger news is that in September 2012 the US government will require car makers to provide access to any crash data saved by their cars. The data will also have to conform to certain standards, increasing the quantity and quality of information available to accident investigators.

3. Crash data is volatile. In many cars, the on-board computer module which records crash data must be replaced after the airbags have deployed. Therefore, crash data can get thrown away during repairs. Crash data from less severe crashes can be overwritten by a subsequent crash. If it’s not downloaded soon after a crash, data disappears. Often we are retained after the data is gone. Specially trained police officers called Collision Analysts download data but generally attend only the most severe crashes. Insurance estimators and repair shops would also be good candidates to download data, but it is not currently part of their mandate. In short, crash data often slips through the cracks.

damaged event data recorder

                                                 Photo of a damaged event data recorder

Electronic crash data is a new and powerful source of evidence for the accident reconstruction engineer, but like traditional pieces of evidence it needs to be properly documented and interpreted to be useful. The accuracy, reliability and limitations of electronic crash data have been the focus of recent MEA research resulting in seven peer-reviewed scientific papers. Our goal is to be in the best position to help our clients, and ultimately the court, understand electronic crash data.

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