Citation

Evans L. Transp. Res. Circular 1998; (E-C003): 42:1-6.

Copyright

(Copyright © 1998, U.S. National Academy of Sciences Transportation Research Board)

DOI

unavailable

PMID

unavailable

Abstract

The United States has over 4 million km (2.5 million mi) of low-volume roads. Many do not incorporate the standards of current highway policies. The application of these standards to road improvements would be extremely expensive and in many cases, unnecessary. Low-volume roads present unique design situations that require unique design solutions. Too often though, design standards for major highways are arbitrarily applied to low-volume roads, resulting in significant environmental impacts and costs. The USDA-Forest Service (FS) manages over 480,000 km (300,000 mi) of low-volume roads. Many have a daily traffic of less than 50. FS roads are often located in sensitive environmental situations. As a result, geometric practices associated with high-volume roads have to be modified. To ensure consistency in the application of geometric design standards, the FS developed a National Preconstruction Handbook. This Handbook is consistent with the policies of the American Association of State Highway and Transportation Officials (AASHTO), while still providing flexibility for the design of low-volume roads. The FS recognized that low-volume roads function differently than major highways and that greater design flexibility and engineering judgement are needed. Traffic convenience often assumes a secondary role to the environmental and economic concerns. The FS design philosophy places a high level of responsibility for safety on the road user. By implementing a national low-volume road design practice, the FS has been able to defend against litigation even though some standards vary significantly from the more common highway policies. The FS practices can be successfully adopted by other local road agencies, if the special needs of low-volume roads are recognized and if increased engineering judgement is allowed in the selection of geometric design standards.