Development of the 8th Edition of AASHTO's A Policy on the Geometric Design of Highways and Streets (Green Book)

AASHTO’s A Policy on Geometric Design for Rural Highways (the Blue Book, first published in 1954) and A Policy on Arterial Highways in Urban Areas (the Red Book, first published in 1957) were early nationally recognized standards for geometric design. In 1984, the Blue Book and Red Book were combined to create the first edition of the AASHTO Green Book. The 1984 Green Book was organized around roadway Functional Classification (Local, Collector, or Arterial) and broad Context Classification (Urban or Rural), with design criteria based primarily on motor vehicle users. Subsequent Green Book editions retained this basic framework for geometric design guidance. While the basic 10 chapter framework in the Green Book has served practitioners well for new construction or new location projects, it lacks the guidance needed today for practitioners to select design criteria for multimodal projects. Additionally, public works projects are more sensitive to funding than ever before. In many cases, cost magnitude and cost effectiveness play increasingly large roles in scoping projects. Often, reconstruction projects are limited in scope or available funding or may be affected by physical constraints or social or environmental considerations. In some locations, especially constrained locations, designing to the recommended Green Book criteria is not feasible. Through experience and applied research, practitioners have learned that roadways engineered using flexible design approaches often perform as well or better than robustly designed facilities and adapt better to the unique needs of each contextual design environment. The approaches of context-sensitive solutions and practical design recognize this and offer principles for project development informed by this understanding. The recently published Green Book, 7th Edition introduces three additional context zones (Rural Town, Suburban, and Urban Core), providing a finer-grained contextual basis. The AASHTO Technical Committee on Geometric Design (TCGD) has established the following goals for the 8th Edition of the Green Book: (1) Fully address the issues raised in the 2016 AASHTO Standing Committee on Highways (SCOH) Resolution on Direction of Flexibility in Design Standards; (2) More fully develop the consideration of all transportation modes and the importance of project context to decisions; (3) Change the emphasis from green field construction to projects on existing alignment; and (4) Incorporate performance-based design using modern analysis tools to find effective solutions to actual problems. At the July 2019 TCGD meeting, the TCGD decided the next Green Book, the 8th Edition (GB8), would better serve designers and transportation agencies by reorganizing the Green Book based on context (i.e., rural, rural town, suburban, urban, or urban core) rather than on functional class. The objective of this research is to develop a draft 8th Edition of the Green Book (GB8) suitable for balloting through AASHTO processes.


  • English


  • Status: Proposed
  • Funding: $1000000
  • Contract Numbers:

    Project 07-29

  • 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: 20200728
  • Expected Completion Date: 0
  • Actual Completion Date: 0

Subject/Index Terms

Filing Info

  • Accession Number: 01739647
  • Record Type: Research project
  • Source Agency: Transportation Research Board
  • Contract Numbers: Project 07-29
  • Files: TRB, RiP
  • Created Date: May 18 2020 3:05PM