The Dutch Case of Testing on Future Air Quality: an Example of Improper Model Use in a Decision-making Process

The Dutch Case of Testing on Future Air Quality: an Example of Improper Model Use in a Decision-making Process


M de Jong, J A Annema, TU Delft, NL



The Dutch case of testing on future air quality: a daunting example

Mig de Jong ?
Jan Anne Annema -

In the Netherlands European air quality standards have been implemented in Dutch law in a way that makes every infrastructure construction decision applicable to law suits. In planning new infrastructure it is obligatory to test whether in the future air quality norms may be exceeded. Currently the high uncertainty of these ex ante air quality calculations is ignored completely in the Dutch planning procedure.

This paper will show that this current calculation practice; creating a false sense of certainty, leads to political frustration and to the postponement of building new infrastructure and reconstructing existing infrastructure. Policy makers interpret the numbers in the way they are given by the researchers: as absolute ?true? figures, without regard for their uncertainty. No different future scenarios are provided for, and no bandwidth is given. This practice makes it easy for the industry of environmental associations, who use these figures and their false sense of uncertainty to object to new infrastructure. They doubt the official data or they present different traffic data and air quality estimates that due to the high future uncertainty are as accurate as the official data. In several Dutch new infrastructure cases judges have acknowledged that the official ?absolute? data are flawed.

The case of the Dutch air quality regulation implementation is a negative example. The case shows that if researchers fail to provide insight in the uncertainties of their transport and air quality models and of their future assumptions, they are not helping decision-making. On the contrary, they are making a mess. The paper will give several solutions to tackle this problem. Right now, the official solution chosen is to improve transport modelling and to improve the model usage procedures in order to avoid making mistakes. In the paper it is argued that this official approach makes no sense at all. Transport models are just one source of uncertainty, and not the most important one. Therefore, improving these models (and the model use procedures) is rather useless, and leads to creating a new false sense of certainty. In our solution the basic approach is that researchers should be honest: they should show the policy-maker the high uncertainty related to future estimates.


Association for European Transport