Final report can be found online at: 
http://www.dot.state.mn.us/guidestar/2006_2010/vii/ConceptofOperations.pdf

Appendix A (Background of Mileage-Based User Fees) describes the various approaches to and prior experiences with mileage-based user fees demonstrations in the U.S. and other countries.

Mileage-based user fees can be implemented in a variety of ways. They can be limited to specific areas or facilities or they can be very comprehensive. They can be collected based on simple odometer readings or can be calculated based on careful evaluation of all travel done by a vehicle. They can be a flat fee for each mile driven or can be varied by time of day, class of road, geographic area, or direction of travel. It may even be feasible to set separate prices for each lane of a road. They can be the same for all vehicles or varied based on vehicle characteristics.