ANALYTICAL MODELS FOR VEHICLE GAP DISTRIBUTION ON AUTOMATED HIGHWAY SYSTEMS/

Highway congestion has in recent years become a pervasive problem for urban and suburban areas alike. The concept of Automated Highway Syste ms is based on the belief that integration of sensing, communication, and control technologies into vehicles and highways can lead to a larg e improvement in capacity and safety without requiring a significant a mount of additional highway right-of-way. A fundamental determinant of Automated Highway Systems capacity is the vehicle-following rule, the rule that governs the behavior of vehicles traveling along a common l ane (e.g,, the spacing between any two longitudinally adjacent vehicle s). Vehicle following affects the longitudinal capacity (achievable fl ow within a lane), the lateral capacity (achievable flow between lanes ) and the conflicting relationship between the longitudinal flow and l ateral capacity. The issues are investigated by developing probabilist ic models for vehicle/platoon and gap distributions, for vehicles that travel in platoons, in slots, or as free-agents. Mathematical models are also developed to estimate the completion time of a lane change, w hich can be used as a surrogate for the lateral capacity. Numerical re sults for the three major vehicle-following rules and their comparison are also provided.