The objective of this research is to explore a methodology that can be used for testing and evaluating AVCS technologies, and, in particular, automatic headway control models for trucks operating on rural highways. The emphasis is put on the realization of vehicle headway control in the real world highway systems. System dynamics has been selected as the simulation tool for developing, testing and evaluating vehicle headway control models. The following behavior of human driver in a real world highway environment is studied and simulated. An automatic headway control model, Multiple-mode Vehicle Headway Control (MVHC) model, is developed for single lane, cars and trucks mixed flow control in a rural highway system. Using safety and motorist comfort as MOE criteria and the acceleration noise as the index of motorist comfort, some selected automatic headway control models are evaluated. This study demonstrated that simulation affords a means of modeling control processes with various certain and uncertain factors, and therefore, it plays a key role in the development of automatic headway control systems. / Ph. D.