1. Institute of Transport and Maritime Management Antwerp (ITMMA), University of Antwerp, Antwerp, Belgium.
2. Department of Social and Economic Geography, Ghent University, Ghent, Belgium
3. Urban and Regional Research Centre Utrecht (URU), Utrecht University, PO Box 80.115, NL-3508 TC Utrecht, the Netherlands
4. Netherlands Environmental Assessment Agency, The Hague, the Netherlands.