Traditionally transport and communication services have provided the twin life-support systems of cities, enabling the expansion of city boundaries, providing people with access to employment, services, leisure and other opportunities essential for their economic and social advancement. But in cities across the world -- from Buenos Aires to Lagos and Los Angeles -- the burgeoning urban growth in the latter half of this century and the rapid expansion of city boundaries are placing an enormous strain on these services. The grinding traffic congestion in Bangkok and the massive air pollution in Mexico City could be the forerunners of nightmare scenarios in the rapidly growing metropolises of the twenty-first century.
This strategy features in the framework of Agenda 21 as formulated at UNCED (Rio de Janeiro, 1992), now coordinated by the United Nations Commission on Sustainable Development and implemented through national and local authorities. Agenda 21 recommends promoting efficient and environmentally sound urban transport systems in all countries as part of a comprehensive approach to urban transport planning and management.