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Interpretation Letter 2(09)-62 (I) — Use of Signal Ahead Signs for Ramp Metering

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U.S. Department of Transportation
Federal Highway Administration

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

November 28, 2012

In Reply Refer To: HOTO-1

Mr. Zhongren Wang
Ramp Metering Branch Chief
Caltrans, Traffic Operations
1120 N Street, MS-36
Sacramento, CA 95814

Dear Mr. Wang:

Thank you for your e-mail message of October 29 requesting an official interpretation concerning the use of Signal Ahead (W3-3) signs for ramp metering operations. Your e-mail message references the 2006 Ramp Control Handbook which shows the Signal Ahead (W3-3) sign as part of the advanced warning for ramp metering.

When the 2006 Ramp Control Handbook was published, the 2003 Edition of the MUTCD was in effect. The 2003 MUTCD did not address ramp metering signing. It was not until the 2009 Edition of the MUTCD that ramp metering warning signs were incorporated into the Manual with the RAMP METER AHEAD (W3-7) sign and the RAMP METERED WHEN FLASHING (W3-8) sign. One of the primary concerns with the Signal Ahead (W3-3) sign is that the W3-3 sign warns of a traffic control signal, which assigns right of way to the vehicle. A ramp meter does not. The green indication on the ramp meter allows movement, but does not assign right of way. The driver still has to yield to traffic on the main line of the freeway or expressway. Additionally most ramp meters use a 2-section signal face (red and green only), which differs from the 3-section signal face illustrated on the Signal Ahead (W3-3) sign. Thus, the symbol on the W3-3 sign does not accurately represent the existing condition.

It is the FHWA's official interpretation that the use of a Signal Ahead (W3-3) sign in advance of a ramp meter would not be in substantial conformance with the MUTCD. Furthermore, the W3-7 and W3-8 signs are the appropriate signs to be used with ramp metering as described in Section 2C.37 of the 2009 Edition of the Manual on Uniform Traffic Control Devices.

We have numbered and titled this Official Interpretation as "2(09)-62 (I) — Use of Signal Ahead Signs for Ramp Metering." If you have further questions on this matter, please contact Mr. Eric Ferron of our MUTCD Team at 720-963-3206 or

Thank you for your interest in the uniformity of warning signs on our streets and highways.

Sincerely yours,

Original signed by:

Mark R. Kehrli
Director, Office of Transportation Operations