Abstract: GIS software are currently widely available to urban planners, but it seems that traditional transportation models are hardly adaptable to these tools.  The purpose of this article is to demonstrate the benefits of a comprehensive linking of transit operational data to a road network within transportation object-oriented GIS.  Based on the Totally Disaggregate Approach and object-oriented modelling, the proposed method has been experimented through many applications in the Montreal area:  user information, bus interlining, origin-destination surveys, and infrastructure management.  With interactive planning, the system gathers data from each of these applications and can transfer the knowledge from one to another.  Experiments on bus interlining problems are described in the article.  They imply an appropriate merge of road and transit networks within the GIS.  Primary conclusions show that the system can also be developed in order to integrate real-time data gathered by GPS technologies.