New Generation of Dutch National and Regional Models - An Overview of Theory and Practice

This paper deals with the new generation Dutch national en regional models, used to make forecasts for the long term future of mobility in general and the traffic and transport conditions in particular. The models are used for two main purposes: a) answering policy questions regarding e.g. major infrastructure investments, and b) to forecast the effect of regional infrastructure projects in the exploration and planning phase. The overall focus of the new generation models was to realize maximum consistency. In the previous situation the techniques of the models were in principle the same, but in practice many small differences and deviations resulted in different outcomes that were hard to explain. Different implementations of the same models were used as well as different versions of the same software. Additionally there were differences in input, differences in assumptions, etc. The new suite of models (one national and four regional models that together cover the whole of the country) are built to ensure maximum consistency. This is realized by using the exact same input data, by using the same models, the same model parameters, the same assumptions, etc. In the paper the main reasons for building a consistent system of models for the national and regional level are further explained. The structure of the model as well as the input and output of the model is described in more detail. The most important innovations and major improvements regarding the previous version of the models are described. The lessons learned regarding the project organization of the project are outlined. Finally, the examples of case studies will be used to illustrate the improvements of the developed model system.