Studies show that the effects of projected traffic growth, even in already highly-motorised countries, will exceed the gains from cleaner and more fuel-efficient vehicles, at least in the medium term. A wider variety of measures will be needed, addressing the whole transport field. The basic requirements of integrated transport policies, aiming for sustainable development, are: (1) making the concept of sustainable mobility operational; and (2) understanding the transport system and the interactions between its components. Sustainable mobility could be made operational by using the concept of `bearing capacity of the environment', identifying impact indicators, selecting criteria, and setting limit values. This process is urgently needed at the international level, to increase understanding of the severity of the problems. An integrated transport system would address land use, infrastructure, vehicle technology, travel and driving behaviour, transport and traffic organisation, and other factors. It would be supported by economic, organisational, and technical regulations and incentives. An iterative process can be designed to include socio-economic and environmental trade-offs. An innovative process is discussed, that could support the design and development of long-term transport policies.
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