 Within TRAIL, Erasmus University of Rotterdam, Delft University of Technology, the University of Groningen, University of Twente and Radboud University Nijmegen collaborate.Scientists and researchers of twelve faculties and institutes (spanning the fields of economics, technology, policy and management, and the social and behavioural sciences) form a concentration of experts in the fields of traffic and transport.Over 150 researchers, of whom 80 are PhD candidates, are active in TRAIL (2006).