In the last 35 years in the metropolitan area of Rome there was a threefold leap in terms of KM travelled, due to the increased length of trips and the number of vehicles (650%). This growth has not been matched by a parallel development of the public transport system that has only recorded a 90% increase (in terms of KM travelled) during the same time period. COnsequently the public transport modal share, holding 56% of total motorised trips in 1964, has sharply decreased and today only accounts for 34% of motorised trips.