Research for AASHTO Standing Committee on Highways. Task 423. Planning for a Comprehensive Update and Restructuring of AASHTO's A Policy on Geometric Design of Highways and Streets (8th Edition)

The American Association of State Highway and Transportation Officials (AASHTO) Committee on Design is in the final stages of preparing the proposed 7th Edition of A Policy on Geometric Design of Highways and Streets (the Green Book) for AASHTO balloting. The basic format, structure, and design philosophy are essentially unchanged since the 1984 edition which combined AASHTO’s rural and urban design policies (the Blue Book and Red Book, respectively). In 2011, the AASHTO Highway Subcommittee on Design requested a National Cooperative Highway Research Program (NCHRP) project to review how the design process has changed over the decades and to provide recommendations on the role and content of a Green Book for a modern design process. NCHRP Report 839, A Performance-Based Highway Design Process, recommends the following as guiding principles for an effective highway design process: (1) Geometric design solutions should address objective, quantitative measures of transportation performance; (2) All potential, legal road users should be explicitly addressed; (3) Operational solutions should be integrated with geometric elements; (4) The process is forward looking; (5) The process must be context sensitive to the extent possible; (6) The process must be financially sustainable at both the program and project level; and (7) The prevailing social and public policy framework must govern. Based on those principles, the report outlines a performance-based design process that takes into account the resources and tools available to modern designers. The report also recommends a fundamental rethinking and restructuring of the Green Book to align with the recommended process. One key structural recommendation is separating the geometric design process for new roads from the process for roads to be reconstructed. The report begins to describe steps needed to fully implement the recommended process. In addition to recommendations on needed research, the report summarizes implementation challenges that will be faced based on a review of the industry’s experiences in adopting the load resistance factor design for bridges, context-sensitive solutions, and the Highway Safety Manual. The AASHTO Committee on Design supports the further development of the recommendations of NCHRP Report 839, recognizing that fundamentally changing a critical reference document will be a significant undertaking. The Green Book influences many functions of state and local departments of transportation (DOTs) and substantive changes will necessitate changes in other standards and policies. The AASHTO Committee on Design also recognizes that it will be prudent to address issues raised by the National Association of City Transportation Officials (NACTO) in its Urban Street Design Guide and to engage city transportation officials in an effort to have as much compatibility as possible between AASHTO and city design guidance, based on the results of solid research. This project will develop a detailed roadmap to develop and implement the 8th Edition of the Green Book that supports a performance-based design process as described in NCHRP Report 839. A key element of this work will be to engage a diverse set of stakeholders to vet the recommendations in the report, better identify the challenges that will be faced in development and implementation, explore solutions to those challenges, and build support for this radical change. These stakeholders will include AASHTO committees dealing with related topics and external stakeholders such as Institute of Transportation Engineers (ITE), Association of Metropolitan Planning Organizations (AMPO), and National Association of City Transportation Officials (NACTO). It is expected that many tasks in the roadmap will be submitted in the future for funding by the NCHRP, though alternative development approaches and funding sources should be identified when appropriate. Since many state and local agencies are eager to begin to implement aspects of the process described in NCHRP Report 839, the plan should seek to support early adopters and benefit from their experiences.


  • English


  • Status: Proposed
  • Contract Numbers:

    Project 20-07, Task 423

  • 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:

    Derr, B

  • Start Date: 20171219
  • Expected Completion Date: 0
  • Actual Completion Date: 0

Subject/Index Terms

Filing Info

  • Accession Number: 01650689
  • Record Type: Research project
  • Source Agency: Transportation Research Board
  • Contract Numbers: Project 20-07, Task 423
  • Files: TRB, RiP
  • Created Date: Nov 13 2017 3:03PM