Q: How does law enforcement determine the speed of a vehicle after an accident has occurred?
A: After an accident has occurred, law enforcement has several different ways to determine the speed of the vehicles involved. One method is measuring the length of skid marks of the involved vehicles and determining the drag factor for the road surface. This data is then entered into a minimum speed equation to obtain the minimum speed of the vehicles. Another method is to download data from a device known as a Event Data Recorder, which is present in modern vehicles equipped with seat belts and air bags. This device can be compared to an aircraft’s “black box.” Vehicle speed is one parameter recorded by this device. Speed data can be obtained from vehicles with GPS tracking and recording devices. These GPS units or tracking devices are becoming more common on commercial motor vehicles.–Sheriff Joel Brott