Site code: A knowledge-based model of municipal site development regulations for computer-aided design

A comparative study of the legal framework of site development regulations in Austin, Texas, San Diego, California, and Fairfax County, Virginia was undertaken to gain insight to the generic structure of such regulations, and to study how regulations could be incorporated into systems for computer-aided design. This study showed that the legal framework of site development regulation can be used to create an organizational system for regulations. The organizational system is utilized to isolate the subset of regulations that are applicable to a given site development project, and is based on: (1) the geographic district in which a regulation is applicable, (2) the time period during which a regulation is effective, and (3) the administrative or legal process (zoning, subdivision, or site review) with which a regulation is associated. Additionally, a relationship is identified between the amount of regulatory discretion available to a municipal government and the types of knowledge sources from which site design requirements are derived. This relationship has important implications on knowledge engineering and the practical development of automated regulatory information systems. Based on the results of the comparative study, conceptual models of a land development permitting process and a substantive design regulation are formulated. A knowledge-based computer model of a municipal site development code is created using the conceptual models as guidelines. This computer application, called SITE CODE, extracts from the regulatory knowledge base all regulations which are applicable to a particular development project. The SITE CODE architecture includes data entities called "regulation objects" which symbolize substantive regulations. A regulation object is linked to a set of rules representing the logic of the regulation, and possesses information used to determine if the regulation is potentially applicable to a given project. A matrix interface allows the user to obtain information contained in the regulations by initiating the evaluation of rules linked to selected classes of regulation objects. Determining which design requirements affect different areas of a single site requires a geometric representation of the site, and necessitates interaction between models of site geometry and regional geography.