Using GPS Based Data Acquisition in Forensic Accident Reconstruction

This paper investigates the use of low-cost global positioning systems (GPS) in typical accident reconstruction scenarios. The GPS-based data acquisition systems acquire GPS position and speed and use internal accelerometers to record lateral and longitudinal acceleration. In addition, most of these GPS systems are expandable to acquire other vehicle measures such as engine RPM, brake signals, accelerator signal, steering wheel sensor, engine instrument data, and onboard diagnostics data. This study evaluated a data acquisition unit that was primarily designed for race car data acquisition, but could easily used in accident reconstruction. The study showed that these systems are able to resolve distances over a short time period to 0.75 ft uncertainty, and their internal accelerometers can measure longitudinal and lateral accelerations with 1.7% uncertainty. For deceleration skid testing, the GPS system provides very similar results to the widely used VERICOM system. The average deceleration for both systems was within 1.5% for all test cases. When acceleration measures are required at more than one location, the data from each unit can easily be synchronized using the built-in GPS time stamp in both data streams.