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Interpretation Letter 9(09)-74 (I) — Decimal Distances on Bicycle Destination Guide Signing

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U.S. Department of Transportation
Federal Highway Administration

1200 New Jersey Avenue, SE.
Washington, D.C. 20590

January 29, 2015

In Reply Refer To: HOTO-1

Mr. John Eisinger
Bicycle and Pedestrian Coordinator
Louisville Metro Department of Public Works
444 South 5th Street
Suite 400
Louisville, KY 40202-4311

Dear Mr. Eisinger:

Thank you for your December 31, 2014, electronic mail requesting an official interpretation of the Manual on Uniform Traffic Control Devices for Streets and Highways (MUTCD) regarding the use of decimals for distance information on bicycle Destination guide signing.

The use of fractional distances on all guide signs is an established, effective practice that meets the expectations of the road user. The purpose of the distance is to provide an approximation of the relative distance it will take to reach a destination. Placing the destinations in the order in which they are reached also helps the road user estimate progress and orient oneself. The near-exact distance is neither critical nor intended for navigational purposes. When the distance is greater than one mile (and in many cases even with lesser distances), the distinction between 2¼ (2.25) and 2 3/10 (2.3), for example, is immaterial for the purpose as explained heretofore. This principle is supported in Paragraph 2 of Section 2E.33 of the MUTCD.

Also, displaying fractions less than one-quarter mile in highway settings is rare and usually avoided because the reaction time and short distance to maneuver to the decision point or destination has the potential to violate driver expectancy. In these situations, guide signing sometimes converts short distances to feet and displays distances less than one-quarter mile as 500 FEET or 1000 FEET. This principle is consistent with the above sign design principles where it is not necessary to provide near-exact distances for navigational purposes.

With the exception of Reference Location signs, which display distance numerals in a vertical format, the display of distances in decimal format on guide signs is to be avoided due to visibility and legibility concerns. Where the total distance is less than one-quarter mile and a need to display a distance in miles instead of feet has been determined, fractions in the form of 1/10 or 2/10 can be used to communicate distance information regardless of the guide sign or setting.

We appreciate the opportunity to clarify the intentions of the provisions of the MUTCD and trust that this interpretation will address your concerns. For recordkeeping purposes, we have assigned your request the following Official Ruling number and title: "9(09)-74 (I) — Decimal Distances on Bicycle Destination Guide Signing." Please refer to this number in any future correspondence.

Sincerely yours,

Original signed by:

Mark R. Kehrli
Director, Office of Transportation Operations