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The concept of intermediate system has to be considered in relation with the search for a good compromise between advantages and inconveniences of bus and subway. A system supplying a quality of service close to the subway's one, but allowing a spatial cover less costly and a larger flexibility and adaptability of the offer to demand, corresponds to an important market that does not justify a large capacity system such as a subway. The concept of rubber-tyred intermediate guided transit system appeared as an attractive means to combine for the medium importance projects, the qualities of the light rail transit with the economic benefits of the road systems, to achieve in some manner a light rail system at the best cost. The first assessments showed that it is possible to achieve 30% of a standard light rail investment cost adopting such a system. This paper deals with analyzing the buses, trolleybuses and guided vehicles intermediate systems field of application. We describe in a first part, the industrial offer of rubber-tyred systems and streecars and in a second part we analyze the applying domain with benefits recalling the inherent qualities of tyre, and limits of these systems. At the end, we analyze research and development which could lower the cost and we consider the intermediate system capacities : we always keep in mind that transit project costs are in relation to the transit offer.
Buses account for most of the journeys made on the public transport system: 76,8% of such journeys are actually serviced by buses, 32,3 % on inter-urban buses and 44,5 % on urban buses. The tram has not been in operation since 1968 and it is left to the bus to make up for low coverage of the underground (50 km) and metropolitan train (270 km) systems. In the opinion of the users buses make up for the inadequate underground system and is more accessible.
Les autobus jouent un rôle prépondérant dans les déplacements effectués en transports collectifs : 76,8% de ces déplacements sont en effet assurés par les autobus dont 32,3% par les autobus interurbains et 44,5% par les autobus urbains. Le tramway n'étant plus exploité depuis 1968, c'est l'autobus qui complète la faible couverture des réseaux de métro (50 km) et de train métropolitain (270 km); dans l'opinion des usagers, l'autobus supplée à la faiblesse du réseau de métro et il offre une meilleure accessibilité.