Positional Accuracy of Portable GPS Devices during Different Ride Conditions 2022-01-0828

Rising electric scooter popularity has seen a surge in electric scooter crashes. Crash reconstructionists increasingly have access to global positioning system (GPS) data for micromobile vehicle trips, and GPS devices can produce a wealth of data about cyclists’, scooterists’, and other riders’ road paths and route usage.

However, prior research has demonstrated that GPS positional accuracy is less reliable for more nuanced roadway positioning, such as which lane a vehicle occupies, as well as within-lane movements, such as acceleration and deceleration⁠. This limitation presents a challenge for crash reconstructionists that may have access to GPS data and require second-by-second positional accuracy to determine such nuanced maneuvers and vehicle positioning in their analysis.

The purpose of this study was to explore the positional accuracy of five GPS units for a micromobile vehicle during three different ride conditions: acceleration, deceleration, and constant speed. The same devices were also tested for stationary accuracy and power cut-off scenarios. To obtain precise data from GPS units, tests were performed with an electric scooter ridden in rural landscapes with clear skies.

Location data from the portable GPS devices were compared to reference data obtained from photogrammetry methods based on video recorded by DJI Mavic 2 drones. It was found that the overall average positional deviation from baseline across the devices and three ride conditions was 6.68 ft. The five devices also showed inconsistencies for which of the three ride stages had the greatest and least positional error. These findings can help investigators and crash reconstructionists quantify these devices’ GPS positional accuracy when using such data in their forensic analysis.