Abstract An expert system for forecasting roadside development along projected roads and streets in urban and suburban areas has been developed which runs on a personal computer. In answering step by step queries from the computer, it is possible to predict a range of probabilities of occupation and development of a wide variety of building types. The input variables used are traffic volume, number of lanes, type of street, population size, the existence of public establishments, building regulations, and other miscellaneous information. The knowledge base is constructed by synthesizing such information from books which contain theories and standards, from various maps as well as from interviews with urban planners and experts in small business management. An illustration of the way the knowledge base is developed and the way the system addresses queries through typical inputs to and outputs from the program is provided.