The objective of this paper is to present the methodological developments in the DIDAM (Disaggregated demand and assignment models for combined passengers and freight transport) research project, which aims at advancing fundamental research in transportation modelling and analysis, using two complementary methodologies. The first is to develop a joint methodological approach for both freight and passenger transport, and the second is to base this common approach on the use of models that are as disaggregate and realistic as possible. Furthermore, the methods will be designed to cope with the important question of competition for infrastructure. The project is mainly organized around two themes. Each of them covers both freight and passengers aspects, in a manner which promotes collaborative work between the partners of the project. The first theme is concerned with disaggregate demand modelling issues, the second deals with innovative aspects of (joint) traffic assignment. Working at a fully disaggregate level is however not always easy. If such models are already available for passenger demand and traffic, disaggregate tools are still largely missing for freight transport. This is not only true at the operational level, but, more crucially, at the conceptual level. This is why our research program adopts, in this domain, a progressive approach that introduces disaggregation gradually into existing methods and models. This entails research in a full spectrum of issues, ranging from concepts definition (who are the actors, how can they be characterized ...) to validation exercises using available data source
