支撑可能한 都市交通計劃 試論

The urban transport problem is universal. A wide variety of manifestations of the problem may be different from place to place, but underlying causes are the same. New roads are free to their users, generate faster and longer trips, more trips by car and higher car ownership, all of which adds up to more traffic. They also undermine the use of public transport. The problems are worsening as urban populations grow and become more affluent. Doing nothing cannot be a solution, because left to itself, the urban transport problem tends to get worse. It is possible, however, to remedy the situation so that congestion is limited, pollution minimized, and the majority of urban residents can travel in safety and relative comfort, but this requires intervention by the urban transport planner. There are serious problems with the application of urban transport planning to cities throughout the world. The planning process has favored roads and suburban sprawl to the detriment of other transport modes and more compact forms of development. Environmental traffic management may, however, attempt to minimize travel, maximize accessibility, reduce environmental impacts, and lessen the social burdens of transport decisions that currently fall hardest on the disadvantaged. Although new technology may contribute to improving the efficiency of urban transport, it cannot solve the transport problem. Urban and metropolitan areas have a dynamic relationship between their structure - their size, density, shape, and distribution of land uses - and their transport systems. As structures change, so new trips are generated and new transport needs emerge. Transport investment takes place to meet these needs and itself alters the relative accessibility of places, the result being changes in land value and land use which starts the whole cycle off again by generating new transport demands. Policies which have attempted to "build the problem away" by providing new capacity to meet unlimited demand have been undermined because new roads have promoted new development along their corridors and at their terminals. Such new development has generated new traffic which has overloaded the roads almost as soon as they are completed. The response has been to plan more new roads as a way of alleviating the new congestion, justifying them in terms of time and fuel savings from reducing congestion. The process immediately becomes a vicious circle of congestion, road building, sprawl, congestion, and more road building. The way out of their impasse lies in the realization that rather than the land use planner providing facilities to meet the demand, it is vital that the land use planner places facilities in locations where they will minimize the need for movement. This is the environmentally sound, minimalist solution, demonstrating that non-transport approaches are as significant in the achievement of civilized cities as planning for transport. The global village is part affluent and transport-rich and part hungry, poverty stricken and transport-poor. But it is a rapidly changing world too, with the political and economic development of the late twentieth century, such as technological innovation in transport and telecommunications; reduced constraints on trade and the related emergence of a world economy; deregulation and privatization in transport; the widening mobility gap between rich and poor; growing urban congestion; increasing scarcity of energy resources; and an increase in environmental awareness. One could obviously contrast the continental European tradition of transport as a means of improving society, with American attitudes which regard transport almost as an end in itself, doubtless a reflection of the American love of newness, movement, and constant change. However, throughout the world the growing reliance on the market is generating new problems which are not easily remedied by conventional market mechanisms, the global pollution f