The Netherlands National Model: A review of seven years of application

Disaggregate modelling is now firmly established as a powerful and practical alternative to the traditional four-stage models originally developed in the sixties. The disaggregate methodology was originally pioneered in the United States, but much important development has taken place in Europe in the 1980s. The basis of the modelling and the scope of the models both broadened and developed. A substantial advance was made by establishing a link between the models and classical theories of micro-economics, allowing the development of ‘behavioural’ models consistent with rational decision-making. The competitive, or sometimes complementary, roles of other modes of travel have been recognised and brought into the modelling framework. In recent years, forecasts of travel demand have been generated in studies in a number of countries in Northern Europe. These studies have encountered a common problem, which is that the assumptions and capabilities of the standard methodology have not been appropriate to address the problems of planning facilities in the early twenty-first century. Amongst the principal difficulties are: 1. the population base is expected to change radically in terms of its age distribution-this the legacy of the Second World War, increased life expectancy and the aftermath of altered behaviour concerning family formation, linked to an increased participation of women in the work force; 2. the work force itself is expected to be radically different, also due to increased female participation; 3. there is an increasing pressure to suppress travel by private car, by any means politically feasible, in the anticipation of growing damage to the environment; 4. in consequence to the previous remark, there is the emergence of new types of travel (in particular, organised car-pooling) and new types of regulation of movement (‘demand management’ measures to control car commuters, and road-pricing policies to reduce peak-hour demand). Increasingly, the modellers are asked to look at very different futures to the present day, and the models themselves are required to perform a role very much more demanding than the mere extrapolation of present day trends. This paper reviews the performance of one particular disaggregate demand model system, the Netherlands National Model, used over a period of seven years to address the problem of producing forecasts appropriate to these new circumstances. The emphasis is on the results of the work, and the lessons that have been learned in the application of the system. Some discussion is given around the extension planned to the system in coming years.