There has been increasing interest in the exploitation of advances in information technology (e.g., mobile computing and wireless communications) in surface transportation systems. Classes of applications that could benefit from such an infrastructure include:• Driver assistance and safety applications: Traffic information or hazardous road conditions may be disseminated to avoid congestion and improve safety.• Commercial applications: Information systems of roadside businesses (hotels, restaurants, gas stations, etc.) can be made accessible to travelers to disseminate up-to-date information (e.g., availability, pricing), or provide services (e.g., reservations, Internet access) to travelers.• Entertainment applications: Passengers may be able to communicate with other, nearby travelers.