Hierarchical Transport Models In The Netherlands

Abstract

The Netherlands has a few decades of experience with hierarchical transport models. They originate from limits of computation in the past and even present. Hierarchical transport models are used at different spatial scales. Their main goal is to keep consistency between the spatial scales. An example is the Dutch National Model System (NMS) and the Netherlands Regional Models (NRM). These were developed in the nineties and updated and further developed several times since then. While these models already exist for about thirty years, only since the last ten to fifteen years activities have been undertaken to make these models more consistent, both concerning their inputs such as base matrix, networks and socio-economic data as their modelling techniques. The reason for making the models more consistent stems from the fact that the models showed different results for the same parts of the road networks and matrix values as well. This situation led to unreliable results, delays in the planning process and extra costs. In order to avoid this situation, the NMS and NRM have been aligned. This improvement played and continues to play an important role between the national and regional level (the Netherlands is partitioned in four regions).Similar problems consist for the interface between the provinces (12) and the areas from which they are built up. Since about ten years a further step in hierarchic transport modelling has been made at the level of provinces. Using a province wide modelling approach, attempts were made to align the transport models of provinces with those from the different sub-regions or municipalities in the provinces. Some attempts were successful, while other attempts failed. Different causes can be mentioned, both concerning the organization as the models themselves.The Province of Noord-Brabant had a successful attempt to build a hierarchical transport model. Both concerning the model system as the organization the hierarchical transport model BBMA can be regarded as a good suite of models with one top transport model for the entire province and four regional models to serve the regions in more detail with results. The first model was realized in 2013. Currently a further improvement of this hierarchical model system is at its final stage of development, featuring even more consistent results on all levels.The paper addresses the hierarchical transport models from a historic perspective by looking at the NMS and NRM, the modelling approach used in different provinces and more specifically the Noord-Brabant hierarchical model. It deals with the problems that have been encountered in the past as well as with the current hierarchical transport model that has been built for the Province of Noord-Brabant. We will provide an overview of both Noord-Brabant models and the way they relate to each other, the problems that had to be solved (such as consistency and flexibility on data, method and results) as well as the way the Province has organized the hierarchical transport model BBMA (such as collaboration between the different stakeholders).