This report has been reproduced directly from the best available copy.Available to DOE
EXECUTIVE SUMMARYThe continued growth of highway traffic in the United States has led to unwanted urban traffic congestion as well as to noticeable urban air quality problems. These problems include emissions covered by the 1990 Clean Air Act Amendments (CAAA) and 199 1 Internodal Surface Transportation Efficiency Act (ISTEA), as well as carbon dioxide and related "greenhouse gas" emissions. Urban travel also creates a major demand for imported oil. Therefore, for economic as well as environmental reasons, transportation planning agencies at both the state and metropolitan area level are focussing a good deal of attention on urban travel reduction policies. Much discussed policy instruments include those that encourage fewer trip starts, shorter trip distances, shifts to higher-occupancy vehicles or to nonvehicular modes, and shifts in the timing of trips from the more to the less congested periods of the day or week. Some analysts have concluded that in order to bring about sustainable reductions in urban traffic volumes, significant changes will be necessary in the way our households and businesses engage in daily travel. Such changes are likely to involve changes in the ways we organize and use traffic-generating and-attracting land within our urban areas. The purpose of this review is to evaluate the ability of current analytic methods and models to support both the evaluation and possibly the design of such vehicle travel reduction strategies, including those strategies involving the reorganization and use of urban land.The review is organized into three sections. Section 1 describes the nature of the problem we are trying to model, Section 2 reviews the state of the art in operational urban land use-transportation simulation models, and Section 3 provides a critical assessment of such models as useful urban transportation planning tools. A number of areas are identified where further model development or testing is required. The following is a synopsis of each section of the review.Section 1 of the review describes the considerable technical difficulties associated with identifying the causes and directions of urban traffic growth. It is concluded that to be effective, transportation planning needs to bring together an understanding of (1) how the transportation sector operates, (2) how trfic-generating and attracting land is developed, (3) how other technologies affect the demands for travel, (4) how modem companies make their siting and site relocation decisions, and (5) how the modem industrial lifestyles of today's households affect, and are in turn affected by, each of the above. Besides the complex conceptual issues involved, challenging practical issues result from the need to handle large amounts of spatially explicit data, and the need to consider a wide range of possible, and sometimes competing transportation control measures (TCM). Significant, sustainable, and socially acceptable travel reduction strategi...