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U.S. Department of Transportation
Federal Highway Administration
1200 New Jersey Avenue, SE.
Washington, D.C. 20590
February 13, 2013
In Reply Refer To: HOTO-1
Mr. Dennis Agar
Division of Traffic Operations
California Department of Transportation
P.O. Box 942873, MS-36
Sacramento, CA 94273-0001
Dear Mr. Agar:
Thank you for your letter of January 22 requesting an official interpretation regarding the required number of signal faces for ramp control signals for single-lane entrance ramps and for separately-controlled multi-lane entrance ramps.
For single-lane ramps, the provisions of Paragraphs 3 and 10 of Section 4I.02 in the 2009 MUTCD are clear that two signal faces are required.
For separately-controlled multi-lane ramps, Paragraph 4 of Section 4I.02 in the 2009 MUTCD requires one signal face mounted over the approximate center of each lane. Based on this paragraph, for a two-lane entrance ramp where the green indications are not displayed simultaneously to each lane, providing one signal face centered over each lane would be sufficient to comply with the MUTCD.
An interpretation was issued in January 2011 (Official Ruling 4(09)-6) that requires two signal faces for each separately-controlled lane of a two-lane ramp, but gives more flexibility regarding the locations of the signal faces (overhead versus side-mounted), which was the concern of the Minnesota DOT when they asked for the interpretation.
As you know, Standard statements in the MUTCD go through a formal rulemaking process that provides practitioners a chance to comment on any new requirements before they are included in the MUTCD. After a Standard statement is added to the MUTCD, the Federal Highway Administration (FHWA) can make the Standard statement less restrictive through an interpretation if someone brings to the FHWA's attention a condition where the requirement cannot be applied. However, the FHWA cannot make Standard statements more restrictive through an interpretation, as this is an action that can only be accomplished through formal rulemaking.
With the foregoing in mind, if you install one ramp control signal face for each separately-controlled lane of a two-lane entrance ramp, your installation will be compliant with the MUTCD despite what is stated in Interpretation 4(09)-6. The provisions of Interpretation 4(09)-6 would give you the added flexibility of mounting the one required signal face for each of the lanes either overhead or on a pole at the side of the ramp.
It is the FHWA's official interpretation that a minimum of two ramp control signal faces are required for a single-lane ramp (and for a multi-lane ramp always having simultaneous green indications for all of the lanes), and that at least one ramp control signal face is required for each separately-controlled lane of a multi-lane entrance ramp where green indications are not always simultaneously displayed to all of the lanes.
For recordkeeping purposes, we have assigned the following official ruling number and title: "4(09)-29 (I) — Required Number of Ramp Control Signal Faces." Please refer to this number and title in any future correspondence regarding this topic.
Thank you for your interest in improving the clarity of the provisions contained in the MUTCD.
Original signed by:
Mark R. Kehrli
Director, Office of Transportation Operations
United States Department of Transportation - Federal Highway Administration