1. Department of Transport and Planning, Faculty of Civil Engineering and Geosciences, Delft University of Technology, Stevinweg 1, P.O. Box 5048, 2600 GA Delft, Netherlands.
2. Arcadis Nederland BV, Divisie Mobiliteit, Verkeer & Vervoer, Adviesgroep Strategie & Beleid, Beaulieustraat 22, P.O. Box 264, 6800 AG Arnhem, Netherlands.