Reducing Metropolitan-Area Congestion
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 Addition of new highway capacity in metropolitan areas to relieve congestion is controversial for reasons of cost, environmental impact, and adverse effects on neighborhoods and households. Modest additional capacity and traffic control improvements to the already large built network can improve traffic flow and reduce emissions. The cumulative effect of many small improvements, however, can increase traffic. Large additions to capacity on the periphery of metro areas will affect demand and, without adequate land use controls, additional low-density development. Decisions about new transportation facilities involve analysis of the social benefits and costs that exceeds the capabilities of current models and procedures, suggesting the need for substantially improved approaches. |
 Public demand for transit in U.S. cities is unlikely to match that in the cities of Europe and Canada without being accompanied by the steep fuel taxes, land use controls, and transit priority policies practiced in those jurisdictions. Even so, transit use could be increased in many large metro areas with established transit systems. A number of practices and policies in effect in Europe and Canada are especially relevant in these areas, from channeling development to locations well served by transit to creative marketing and fare policies. |
 In growing metropolitan areas with heavily used highways and transit systems, reducing the congestion associated with transportation will require both market-based (pricing) approaches and the provision of new facilities. Pricing strategies, however, lack broad public understanding and acceptance. Thus experimentation with and evaluation of incremental steps toward user fees that vary with demand will be necessary. |
 Advanced technological solutions to urban congestion, although proven technically, are quite difficult to introduce unless they can be blended into the complex interplay of market demand and existing institutional arrangements. Nonetheless, continued technological innovation is vital to providing the capacity needed to meet increasing demand. Although full automation of highways is problematic both technically and socially, society would benefit from the increased development of technologies designed to facilitate communication between roadsides and automobiles. |