The objective of this paper is to review object-oriented (OO) approaches to data modeling and data handling and their usefulness in transportation planning and modeling in general and Intelligent Transportation Systems in particular. The paper begins with a discussion of the current GIS data model for representing a transportation network and the most common database management systems used in the context of transportation planning. We then discuss object-orientation, its different properties and its usefulness in representing a multi-modal, multi-scale network with hierarchical road types. We also discuss alternative database management schemes. Finally we review some existing systems and discuss the implications of adopting an object-oriented perspective.