1. Department of Statistics and Operations Research, Universitat Politècnica de Catalunya, Barcelona, Spain
2. Institute of Transportation and Urban Engineering, Technische Universität at Braunschweig, Braunschweig, Germany
3. Civil and Environmental Engineering, Universitat Politècnica de Catalunya, Barcelona, Spain
4. Department of Enterprise Engineering, Università Degli Studi di Roma Tor Vergata, Rome, Italy