The University of Tennessee, Knoxville


MUTCD Reminder: Experimentation vs. Interim Approval

by Matt Cate, P.E.

The Manual on Uniform Traffic Control Devices (MUTCD) is the national standard governing all traffic control devices (TCDs) on U.S. roadways. All public agencies and owners of private roads open to public travel across the nation rely on the MUTCD to create a uniform experience for all roadway users. Failure to comply with the MUTCD can ultimately result in the loss of federal-aid funds and can significantly increase tort liability.

The success of the MUTCD in achieving a goal of uniformity among TCDs across all jurisdictions depends on complete nationwide acceptance and application of the manual as well as extensive participation by the practitioners in developing and evaluating the content of the MUTCD. This article highlights proper procedure for local agencies to ensure they are in full compliance with the MUTCD when using TCDs through permission to experiment or interim approval.


Agencies can use new TCDs that are not currently addressed by the MUTCD only after permission to experiment has been granted by FHWA. In these cases, the agency having jurisdiction over the roadway must ensure the device conforms to applicable provisions of the MUTCD and can only be used on roads open to the public under the conditions and criteria detailed in FHWA's experimental approval.

All requests for experimentation should originate with the State/local highway agency or toll operator responsible for managing the roadway or controlled setting where experiment will take place. The FHWA Office of Transportation Operations must approve the experiment before it begins. See Section 1A.10 of the MUTCD and the Experimentations page on the MUTCD web site ( for details on what information must be included in the experimentation request.

FHWA details some experimental TCDs on its website. One such example of this information is found on the FHWA Bicycle and Pedestrian Program site ( This page details several active experiments and interim approvals for bicycle-related TCDs, including two-stage turn boxes, bicycle boxes, dashed bicycle lanes, green-colored pavement for use with the shared-lane marking, green-colored pavement for bicycle lanes, and bicycle signal faces.

There are currently four active experiments in Tennessee. Additional details of these experiments, detailed below, can be found using the MUTCD Official Rulings database (

Interim Approval

Interim use of new traffic control devices that are pending official rulemaking, a revision to the application or manner of use of an existing traffic control device, or a provision not specifically described in the MUTCD are allowed with Interim Approval. Interim Approvals are considered by the FHWA Office of Transportation Operations based on the results of successful experimentation, studies, or research, and an intention to place the new or revised device into a future rulemaking process for MUTCD revisions.

Any jurisdiction that wishes to use a device or application that has received Interim Approval must submit a written request to the FHWA Office of Transportation Operations. Please see the Interim Approvals page on the MUTCD website ( for details on what information must be included in the Interim Approval request. The request must indicate whether blanket jurisdictionwide approval is being requested or must state the location(s) where the device will be used, and must include the jurisdiction's agreement to comply with items B, C, and D in paragraph 18 of Section 1A.10 of the 2009 MUTCD. A state department of transportation may request Interim Approval for all jurisdictions in that State. Within 3 months following the issuance of a Final Rule on this traffic control device, the local jurisdiction must implement any changes necessary to bring the traffic control device into compliance with the final rule or restore sites of Interim Approval to their previous condition.

There are currently eight valid Interim Approvals in effect for the 2009 Edition of the MUTCD. This list includes:

Complete details for each item can be found on the Interim Approvals page of the MUTCD website.

Questions regarding the MUTCD Experimentation and Interim Approval process can be addressed to Bruce Friedman with the FHWA Office of Transportation Operations ( or David Martin with the FHWA Tennessee Division Office ( Official requests for permission to experiment or to use TCDs under an Interim Approval must be made to the FHWA Office of Transportation Operations via


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