The concept of situation awareness (SA)--applied broadly over the last decade to human factors issues in aviation, nuclear power generation, and military combat systems--has only recently been introduced to the analysis of driver behavior. In a driving context, SA involves spatial, temporal, goal, and system awareness. These aspects of SA have been integrated into a goal-oriented model of driver behavior that encompasses strategic, tactical, and operational goals of driving. Maintenance of appropriate SA for each type of goal is based on three underlying processes: perception, comprehension of disparate information, and projection and prediction. The model can be used as a basis for understanding the possible impact of new generations of intelligent transportation systems (ITSs) on driver performance. The model allows ITSs to be analyzed for how they are likely to enhance or impair a driver's performance in pursuit of each type of driving goal. The model may provide a way to determine how an ITS supports or interferes with the required SA to meet a driving goal (e.g., an onboard navigation system that assists strategic decisions).