The major components of transport systems, i.e. traffic and access infrastructure, rolling stock and operating systems, constitute a set of facilities characterized by a long life cycle and high costs. As a result, capital investment decisions carry with them huge consequences, and it is commonplace to prepare all such decisions by performing beforehand a cost/benefit analysis. A standard method has been gradually developed in order to evaluate infrastructure projects (e.g. see the French circular COBA, the English WebTAG), in accordance with recognized scientific guidelines and with impetus provided by public authorities - with major similarities between countries all over the world (PIARC, 2009).