U.S. Department of Transportation
Federal Highway Administration
|Subject:||ACTION: New Design Standards for Projects on the National Highway System||Date:||February 15, 2002|
|From:||/s/ Original signed by:
Dwight A. Horne
Director, Office of Program Administration
|To:||Resource Center Managers
Federal Lands Highway Division Engineers
The final rule to incorporate the latest edition of the AASHTO publication A Policy on Geometric Design of Highways and Streets (2001 Green Book) into 23 CFR 625 was published in the Federal Register on February 12. The final rule is attached for reference. The adoption of the 2001 Green Book, effective March 14, supersedes previous editions of the Green Book as the minimum design standard to be used for projects on the National Highway System (NHS). For new projects, a reasonable transition period of up to a year from the effective date of the final rule would be appropriate to allow the State to review and revise its design standards and manuals to incorporate changes necessitated by the new Green Book. For ongoing projects each Division Office should discuss implementation with their respective State and reach an agreement on the application of the new standards. A copy of the 2001 Green Book was transmitted to each office with our memorandum dated July 19, 2001. A narrative summary of changes in the new Green Book and a slide presentation highlighting some of those changes were transmitted by previous e-mails.
For projects on the NHS, the criteria related to design speed, lane and shoulder width, bridge width, structural capacity, horizontal and vertical alignment, grade, stopping sight distance, cross slope, superelevation, and horizontal and vertical clearance, are controlling criteria and require formal design exceptions when not met. Exceptions from other criteria should also be justified and documented in the project records. Since the NHS is generally composed of arterials and freeways the criteria in functional chapters 7 (Rural and Urban Arterials) and 8 (Freeways) are normally applicable. In the absence of information covering all design criteria in these chapters, the information in chapters 1, 2, 3, 4, 9 and 10 is applicable. Generally, the criteria in functional chapters 5 (Local Roads and Streets) and 6 (Collector Roads and Streets) are not applicable to projects on the NHS. However, if highway segments functionally classified less than arterials are incorporated in the NHS by virtue of being STRAHNET connectors or Intermodal connectors, the criteria used may be those appropriate for the functional classification of the segment taking into account the type of traffic using the segment.
For projects on the Interstate System, the design criteria contained in the current edition of A Policy on Design Standards - Interstate System (Interstate Policy) are applicable. In the absence of criteria in the Interstate Policy, the values in the 2001 Green Book should be used for design of Interstate projects.
Projects not on the NHS are to be designed, constructed, operated, and maintained in accordance with State laws, regulations, directives, safety standards, design standards, and construction standards as specified in 23 USC 109 (o).