ABSTRACT: This paper presents the use of 3D GIS to represent, analyse and explore the most common urban rules described in French local urban planning schemes. As these rules are only expressed in free formed texts, it is difficult to assess their impact on the evolution of the urban environment. A schema is proposed in order to allow the capture and management of urban rules. These rules are applied to a structured geographic environment in order to automatically determine and represent their influence by 3D volumes. Three different applications of the proposed model are explored in this article: (1) to asses or emulate the influence of urban rules in terms of potential constructions (by visual analysis), (2) to determine their influence on the Floor Area Ratio (by spatial analysis), (3) to evaluate preproject building shapes.