Does Compact Development Increase or Reduce Traffic Congestion?

From years of research, the authors know that compact development that is dense, diverse, well-designed, etc. produces fewer vehicle miles traveled (VMT) than sprawling development. But compact development also concentrates origins and destinations. No one has yet determined, using credible urban form metrics and credible congestion data, the net effect of these countervailing forces on area-wide congestion. Using compactness/sprawl metrics developed in an earlier project at the University of Utah, and congestion data from the Texas Transportation Institute’s (TTI’s) Urban Mobility Scorecard Annual Report database, this study seeks to determine which opposing point of view is correct. It does so by (1) measuring compactness, congestion, and control variables using the best national data available for U.S. urbanized areas and (2) relating these variables to one another using multivariate methods to determine whether compactness is positively or negatively related to congestion. The models suggest that an increase in compactness reduces VMT, but also concentrates those VMT. The two effects roughly cancel each other out. This analysis does not support the idea that sprawl acts as a “traffic safety valve,” as some have claimed. However, it also does not support the reverse idea that compact development offers a solution to congestion, as others have claimed. Developing in a more compact manner may help at the margin, and providing more transit service may help at the margin, but the great reduction in congestion appears to be achievable through expansion of surface streets and higher highway user fees.

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• Supplemental Notes:
  • This paper was sponsored by TRB committee ADB40 Standing Committee on Transportation Demand Forecasting.
• Corporate Authors:

  Transportation Research Board

  500 Fifth Street, NW
  Washington, DC  United States  20001
• Authors:
  • Ewing, Reid
  • Tian, Guang
  • Lyons, Torrey
  • Terzano, Kathryn
• Conference:
  • Transportation Research Board 96th Annual Meeting
  • Location: Washington DC, United States
  • Date: 2017-1-8 to 2017-1-12
• Date: 2017

Language

• English

Media Info

• Media Type: Digital/other
• Features: Figures; References; Tables;
• Pagination: 14p
• Monograph Title: TRB 96th Annual Meeting Compendium of Papers

Subject/Index Terms

• TRT Terms: Development; Traffic congestion; Traffic safety; Travel time; Urban areas; Urban design; Urban sprawl; Vehicle miles of travel
• Subject Areas: Highways; Planning and Forecasting;

Filing Info

• Accession Number: 01629530
• Record Type: Publication
• Report/Paper Numbers: 17-05728
• Files: PRP, TRIS, TRB, ATRI
• Created Date: Mar 20 2017 9:23AM