AASHTO DS-6: A Policy on Design Standards—Interstate System, 6th Edition

These standards reflect the minimum standards that apply to Interstate highway segments constructed on new right-of-way and segments undergoing reconstruction along existing right-of-way.

AASHTO DS-6, which include changes based on research and practice since the previous 2005 edition, are designed for use with A Policy on Geometric Design of Highways and Streets (the “Green Book”). Design values are presented in both U.S. customary and metric units.

These objectives can be realized by conscientious attention to design. The following minimum standards apply to Interstate highway segments constructed on new right-of-way and segments undergoing reconstruction along existing right-of-way.

The geometric design standards used for resurfacing, restoration, and rehabilitation (3R) projects may be the AASHTO Interstate standards that were in effect at the time of original construction or inclusion into the Interstate system.
Design values are presented in this document in both U.S. customary and metric units and were developed independently within each system of units. The relationship is neither exact (soft) nor a completely rationalized (hard) conversion.

The values are those that would have been presented in either system. Therefore, the user is advised to work entirely in one system and not attempt to convert directly between the two. In addition, all projects, including 3R, or elements of projects that retain existing geometries meeting the minimum standards for the selected design speed in one system of units are considered in compliance with comparable design speed standards in the other.

The current editions of AASHTO’s A Policy on Geometric Design of Highways and Streets (“The Green Book”) and the AASHTO LRFD Bridge Design Specifications shall be used as design guides where they do not conflict with these standards.