TRAFFIC CONGESTION: TRENDS, MEASURES, AND EFFECTS

To understand more about the nature of traffic congestion, its measurement, and its effects, the General Accounting Office (GAO) initiated a study under the sponsorship of the Subcommittee on Transportation and Related Agencies of the Senate Committee on Appropriations. GAO found that trends in major societal forces have shaped the nature and severity of traffic congestion. It has become a metropolitanwide problem encompassing suburban as well as urban jurisdictions. Transportation agencies use a variety of interrelated measures to characterize congested traffic flow such as higher traffic density and slower speeds, and these measures can differ on what constitutes an unacceptable level of traffic flow for the capacity of a given road. For all measures, however, the level of traffic congestion increases as the volume of traffic reaches the capacity of the road to carry vehicles efficiently and safely. A recent Federal Highway Administration (FHWA) staff study on congestion represents a significant advance toward quantifying urban freeway delay nationwide. GAO found limited empirical investigation of the effects of traffic congestion, although some relationships between congestion and higher business costs, poorer air quality, and behavioral change are generally thought to hold. Some studies have been conducted for each potential area, but it is difficult to separate the effect of traffic congestion from other factors that affect the environment, the economy, and human stress. This resource document is a companion to a GAO report that profiles federal efforts to improve freeway mobility (see GAO/PEMD-90-2).

  • Supplemental Notes:
    • Report to the Chairman, Subcommittee on Transportation and Related Agencies, Committee on Appropriations, U.S. Senate.
  • Corporate Authors:

    U.S. General Accounting Office

    441 G Street, NW
    Washington, DC  United States  20548
  • Publication Date: 1989-11

Media Info

  • Features: Appendices; Figures; References; Tables;
  • Pagination: 86 p.

Subject/Index Terms

Filing Info

  • Accession Number: 00491216
  • Record Type: Publication
  • Report/Paper Numbers: GAO/PEMD-90-1, HS-041 423
  • Files: HSL, TRIS
  • Created Date: Feb 28 1990 12:00AM