A decentralized communication and control system is presented for driving assistance and automation along designated highway segments. This paper is based on a hybrid dynamical model describing vehicular motion, and the structure of a safe controller is presented. A ranging and communication system provides information for a vehicle and its nearest neighbors. The system is capable of handling sudden changes of regime, overtakes, reentries, as well as a number of maneuvers dictated by safety requirements under partially unpredicted events. A user-friendly interface, based on a palmtop computer, is developed to assist drivers visually and acoustically