Framework for Assessing Induced Demand Effects of Various Roadway Investments

Operational improvements such as auxiliary lanes and intelligent transportation system treatments are designed to reduce congestion. Even minor congestion improvement strategies and investments intended to optimize existing roadway system assets are increasingly facing opposition due to the concept of induced demand, often pointing to potentially disparate impacts on Environmental Justice (EJ) communities. The public lacks trust that the traffic analyses accurately account for induced demand and raises concerns about such projects' ncreased greenhouse gases (GHG) and air quality impacts. Recognizing that even operational and safety improvements may have some level of induced demand, state departments of transportation (DOTs) need to understand their potential unintended consequences better. A definitive study of major and minor capacity enhancements on freeways and arterials, as well as mitigation options, is needed to improve state DOT investment decisions for the long term and enable more productive conversations with the public. The public and interested roups are using induced demand arguments to oppose new roadway investments and small operational and safety roadway projects by state DOTs nationwide. To invest responsibly – balancing safety, economic, equity, and climate concerns – state DOTs need to understand better the actual effects of these projects, especially of more minor roadway treatments and other mitigation options. Additionally, with tough tradeoffs, state DOTs would engender more public buy-in through more nuanced discussions. This study would provide a broader understanding of effective roadway congestion strategies. It would help state DOTs avoid investing in projects/treatments that, if left unmitigated, are unlikely to achieve their intended goals. The objective of this research is to create a framework for (1) analysis and (2) communications that will demonstrate state DOTs factor in induced and latent demand while identifying mitigation factors. The effort should note particular circumstances or gaps in case study data collection and research that might require furtherinvestigation. 


  • English


  • Status: Proposed
  • Funding: $450000
  • Contract Numbers:

    Project 08-184

  • Sponsor Organizations:

    National Cooperative Highway Research Program

    Transportation Research Board
    500 Fifth Street, NW
    Washington, DC  United States  20001

    American Association of State Highway and Transportation Officials (AASHTO)

    444 North Capitol Street, NW
    Washington, DC  United States  20001

    Federal Highway Administration

    1200 New Jersey Avenue, SE
    Washington, DC  United States  20590
  • Project Managers:

    Wadsworth, Trey

  • Start Date: 20230828
  • Expected Completion Date: 0
  • Actual Completion Date: 0

Subject/Index Terms

Filing Info

  • Accession Number: 01883937
  • Record Type: Research project
  • Source Agency: Transportation Research Board
  • Contract Numbers: Project 08-184
  • Files: TRB, RIP
  • Created Date: May 30 2023 8:28PM