1. Laboratory of Transport Economics, 14 Avenue Berthelot, F-69363 Lyon CEDEX 07, France.
2. Department of Economics and Traffic, Cofiroute, 6-10 Rue Troyon, F-92316 Sèvres CEDEX, France.
3. Piron Consulting S.A.S., 36 Avenue Alphonse Cherrier, F-92330 Sceaux, France.