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Subject: Information: Level of Service on the National Highway System Date: May 6, 2016
From: /s/ Jerry Yakowenko
Robert B. Mooney
Acting Director, Office of Program Administration
In Reply Refer to: HIPA-20
To: Director of Field Services
Director of Technical Services
Division Administrators
Federal Lands Highway Division Engineers

We have received several questions regarding the minimum level of service (LOS) requirements for projects on the National Highway System (NHS). The Federal Highway Administration (FHWA) adopted the American Association of State Highway and Transportation Officials' (AASHTO) A Policy on Geometric Design of Highways and Streets, 2011 edition (Green Book) as the design standards for the NHS, and AASHTO's A Policy on Design Standards Interstate System, 2005 edition for highways on the Interstate System. General guidance for the selection of design LOS on highway facilities with specific values is provided in Table 2-5 of Section 2.4.5 of the Green Book, which recommends that highway agencies strive to provide the highest LOS practical "as may be fitting to the conditions".

While we concur with this general guidance, we recognize that the recommended LOS values in Table 2-5 may not be reasonably attainable in some situations. Although States may adopt LOS standards in their design manuals, FHWA does not have regulations or policies that require specific minimum LOS values for projects on the NHS. The recommended values in the Green Book are regarded by FHWA as guidance only. Traffic forecasts are just one factor to consider when planning and designing projects. Agencies should set expectations for operational performance based on existing and projected traffic conditions, current and proposed land use, context, and agency transportation planning goals, and should also take into account the input of a wide cross section of project stakeholders.

Also, consistent with Dwight Horne's memorandum dated August 31, 2010 (https://www.fhwa.dot.gov/pgc/results.cfm?id=4643), use of the Highway Capacity Manual for the operational analysis of projects on the NHS is not required if another traffic analysis method is determined to be more appropriate to fully identify and evaluate the performance and impacts of the proposed project alternatives.

Should you have any questions, please contact Michael Matzke at (202) 366-4658 or Elizabeth Hilton at (512) 536-5970.

Updated: 11/15/2018
Federal Highway Administration | 1200 New Jersey Avenue, SE | Washington, DC 20590 | 202-366-4000