Skip to contentSkip to contentUnited States Department of Transportation - Federal Highway Administration FHWA HomeFeedback

DOT logo
U.S. Department of Transportation

Federal Highway Administration

400 Seventh St., S.W.
Washington, D.C. 20590

February 23, 2005

Refer to: HSA-10/SS-127

Mr. Nick Calvi
Ultimate Highway Products, Inc.
P. O. Box 7
10650 Fern Avenue
Stanton, California 90680

Dear Mr. Calvi:

Thank you for your letter of October 22, 2004, requesting the Federal Highway Administration (FHWA) acceptance of revisions to your company's Slip-Mate slip base as a breakaway sign support system for use on the National Highway System (NHS). Accompanying your letter were drawings of the proposed changes. You requested that we find the revised Slip-Mate breakaway base acceptable for use on the NHS under the provisions of the NCHRP Report 350 "Recommended Procedures for the Safety Performance Evaluation of Highway Features." You also requested that products formally tested and accepted under the "Western Highway Products" name and sold by your company be recognized as "Ulti-Mate" products.


Testing of the supports with the original Slip-Mate device was in compliance with the guidelines contained in the NCHRP Report 350, Recommended Procedures for the Safety Performance Evaluation of Highway Features. Requirements for breakaway supports are those in the American Association of State Highway and Transportation Officials' Standard Specifications for Structural Supports for Highway Signs, Luminaires and Traffic Signals.


The original Slip-Mate was a three-bolt omni-directional slip base system - the revisions do not affect this. The 1/2-inch triangular plates measure 6 inches on each side of the triangle. A 1/2-inch thick polypropylene ball bearing housing is placed between the two plates to provide reduced friction. (This is necessary for a smaller system to avoid the problem of the signpost bending before the slip base can separate.) To either slip plate is welded a 2x2 inch by 1/4-inch square steel tube. The upper tube is 18 inches long and is welded to the top slip plate to receive the 12 gage, 2 1/4 x 2 1/4-inch square perforated square steel sign support. This tube is extended so as to contact the vehicle's bumper with a significant cross-section of steel. The lower tube is 6 inches long and is welded to the bottom plate and is inserted in and fastened to the tube and sleeve combination in the foundation. The slip base bolts are 1/2-inch diameter x 2 1/2-inch long hex head steel bolts with nuts and washers. They are torqued to 40-foot pounds. The anchor for the system consisted of a 2 1/4-inch square, 36-inch long 12 gage perforated square steel tube (PSST) with a 2 1/2-inch square, 18-inch long 12 gage perforated strengthening sleeve with a soil stabilize bracket measuring 13 inches by 10 inches attached with two 5/16-inch corner bolts. The system was installed in the NCHRP Report 350 "Standard" soil. The sign used in the test was a 36 x 60-inch rectangular sign attached to the support post with four 3/8-inch drive rivets. It was mounted 5 inches below the top of the 144-inch tall post. The weight of the sign and the post was 60 pounds above the slip plane. The device was accepted in the FHWA acceptance letter SS-100 dated November 21, 2001.

Requested Modifications and Findings

You requested the following modifications to the tested Slip-Mate breakaway device:

We concur with your assertion that these changes should have no adverse affect on the breakaway performance of the Slip-Safe system. Therefore, the modifications to the devices described above and shown in the enclosed drawings for reference are acceptable for use as Test Level 3 devices on the NHS under the range of conditions tested, when proposed by a State.

Ulti Mate and Western Highway Products

Previously your company sold the Slip-Mate and other Ulti-Mate products under the name of "Western Highway Products." You requested that all devices that were accepted under the Western Highway Products name be formally recognized as Ulti-Mate products sold under the company name of Ultimate Highway Products, Inc. The FHWA hereby acknowledges this as it applies to the following acceptance letters issued to Western Highway Products:

SS-100 November 21, 2001 Slip Mate breakaway base
SS-62 June 3, 1996 Ulti Mate perforated square steel tube sign supports
WZ-155 June 9, 2003 Type III Barricades
WZ-155 Revised November 28, 2003 Type III Barricades

Please note the following standard provisions that apply to the FHWA letters of acceptance:

Sincerely yours,

/Original Signed by Harry W. Taylor/

John R. Baxter, P.E.
Director, Office of Safety Design
Office of Safety

3 Enclosures

Safety Home | FHWA Home | Feedback