In a fully automated Automated Highway System (AHS), the roadside control system and the vehicles themselves are responsible for moving the large number of vehicles safely and efficiently. Therefore, the task of operating an AHS is drastically different from and much more complex than its conventional counterpart. Resulting from a large number of design options, there exist many possible ways to operate an AHS. Each of these possible operating scenarios will support a different set of functions. A crucial task in AHS R&D is to evaluate and compare these potentially large number of different AHS operating scenarios with respect to the achievable capacity.To enable simulation of various operating strategies without requiring massive program modification or database change, a flexible software structure and robust database design are required. This in turn necessitates a robust AHS functional architecture that guides the development and evolution of the required simulation tools. This paper identifies major traffic planning functions useful for optimizing the capacity of one or more major AHS operating scenarios and organizes them in a robust architecture that is modular, hierarchical, complete, expandable and integratable.
H.-S. Jacob Tsao. "A Functional Architecture for Automated Highway Traffic Planning" PATH Research Report (1994).