Traveling the OReGO Trail - Jumpy GPS Response

I recently posted a blog entry where I showed that the route shown by the OReGO program is not 100% accurate. 

Bad route data

I asked the OReGO administrators about this and here is their response:

Dear Patrick,

Thank you for contacting Azuga OReGO Customer Care with your concerns. We take them seriously. I'll explain how the route is plotted but want to first assure you that actual mileage readings are provided by the device from the vehicle, not generated from the plotted route.

The device reads GPS Latitude and Longitude values every 30 seconds from the device. The dark blue points on the route denote the GPS point. These lat/long values are sent to Google for reverse geo-coding which is resolved to an address. The route shown on the map is the most probable one taken by the vehicle as determined using the values and mapping software.

Occasionally, a turn or circle that does not belong on your trip is plotted due to GPS drift. These minor anomalies appear on your trip history, but are not used to determine your mileage or Road Usage Charge (RUC). Mileage is measured off of the Vehicle Speed Sensor (VSS) which is the same accurate reading that is sent to your vehicle's odometer.

Again, we thank you for your concern on accuracy as it is a major focus for Azuga. We appreciate you participating in this pioneering road and infrastructure maintenance program and wish you happy driving.

Thank you,
Azuga OReGO Customer Care

There you have it. The GPS location data is not used to determine the trip distance. The route does not need to be perfect for their trip calculations. The GPS location is only needed to determine if you are in the state and on public roads.

I'm still not sure why Google says it was 8.1 miles door to door while OReGO says that it was an 8.3 mile drive. I'll check the odometer next time I make that drive.