EXECUTIVE SUMMARYUrban transportation Planning is facing challenges and opportunities in the rapid developments of intelligent transportation systems. Such systems are characterized by real time information feedback in their operations and management, and by increasing levels of automation of their various components. The challenges to planning stem from the increased range and added complexity of the choices available to transportation planners. The implementation of IVHS technologies, many of which have system-wide implications will require a change in the institutional arrangements that are currently at work in transportation planning. Recent legislation, such as ISTEA and the California Congestion Management Program, has also posed a challenge to transportation planning as it requires specific processes and imposes certain mandates.The opportunities for transportation planning are many and stem from the availability of information, communications, and computation technology. These same elements which add intelligence to the transportation system can be engaged to add intelligence to the planning process itself.We have developed a framework for integrating planning and analysis in a computer supported environment that facilitates deliberation and consensus seeking. The planning process conducted with the aid of an intelligent facilitator benefits from on-line analysis capabilities that are integrated into a unified computer system called PLANiTS. It is constructed around four components: a policy and goals base that helps define the objectives and criteria of the planning process, a strategy and action base that assists in the search for actions to improve transportation systems, a knowledge base in which data, information, and knowledge about the transportation system reside, and a methods and tools base in which planning analysis and operations analysis models are integrated. The last two are supported by an expert system that searches the knowledge base for relevant information and assists the planners in selecting appropriate methods of analysis. These bases are used to support a deliberative process in which alternative strategies are analyzed and evaluated and decision makers are assisted in reaching resolution concerning plans and programming of projects.Transportation actions are represented by planning vectors PV(A, Y,E) that are constructs containing elements of proposed actions A, evaluation criteria Y, and environment descriptors E. Searching through the knowledge base, PLANiTS uses techniques of case based reasoning and pattern recognition to match proposed planning vectors with similar cases. Further, an expert system advises the planners on the adequacy of available knowledge, the need for primary data collection, and the appropriate selection of models for evaluating the proposed planning actions.The proposed planning methodology involves extensive use of knowledge bases in assessing transportation actions. It involves on-line access to knowledge and to modelling capability. By placing the pla...