Locked-wheel tire friction testing was conducted at the site of a single-vehicle collision. This testing was part of the forensic analysis to determine the speed of a passenger van that slid off the roadway while in a turn. An exemplar van was instrumented with a Racelogic VBox III Data Logger. At 100Hz, the VBOX uses the Doppler shift in signals coming from satellites to accurately measure vehicle speed. Data from four tests was used to calculate road surface friction values.