The sustainability of the United States transportation system is threatened over the long term. An aging, congested highway focused system hinders economic prosperity yet revenues are inadequate to pay the cost of long term maintenance and operations. Meanwhile, unintended externalities caused by transportation affect a broad spectrum of human and natural environmental issues and economically disadvantaged groups are unable to share in transportation benefits available to a wider population. In the coming decade, road pricing is likely to become the next step toward creating an economically, environmentally and socially sustainable transportation system.  Its proponents promise that pricing can deliver smarter use of existing capacity that reduce congestion and avoid costly expansion needs while expanding the menu of options for raising money to pay for system preservation and capacity improvements. This research project would explore the case for economic, environmental and social sustainability benefits of road pricing. Research tasks might include: 1) Assess what level of fee would be required to alter driver behavior; 2) Estimate resultant benefits (GHG reductions, etc) form pilot and full scale implementation and 3) Define further research, if any, required.