November 22, 2002

Refer to: HSA-10/SS-116

Mr. Mike Chu
Application/Sales Engineer
Valley Forge & Bolt Manufacturing Co.
1825 South 27^th Avenue
Phoenix, Arizona 85009-6417

Dear Mr. Chu:

Thank you for your October 29 letter requesting Federal Highway Administration (FHWA) acceptance of your company=s SPC4^tm load indicating fasteners as a component of breakaway slip base sign support systems for use on the National Highway System (NHS). You requested that we find these bolts acceptable for use with slip bases on the NHS under the provisions of National Cooperative Highway Research Program (NCHRP) Report 350 "Recommended Procedures for the Safety Performance Evaluation of Highway Features."

Introduction

Testing of slip base sign supports has been conducted 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' (AASHTO) Standard Specifications for Structural Supports for Highway Signs, Luminaires and Traffic Signals.

Breakaway slip bases depend upon proper torquing of the bolts to 1) ensure that the bolts will not loosen markedly and fall out due to vibrations and 2) permit the slip base surfaces to move with respect to one another in the event of crash. Your company's specially modified bolts allow a user to check the tension in the bolts once they are installed. This method also provides the opportunity to check the tension after construction to see if the system has "relaxed" to the point where the bolts no longer keep the system stable. Load indicating fasteners can allow a simpler and more accurate periodic inspection.

Findings

It is our opinion that the load indicating bolts will perform in an acceptable manner when used in crash-tested slip base systems in lieu of the conventional bolts that are specified. Therefore, the devices described above and shown in the enclosed product literature 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.

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

• Our acceptance is limited to the crashworthiness characteristics of the devices and does not cover their structural features, nor conformity with the Manual on Uniform Traffic Control Devices.
• Any changes that may adversely influence the crashworthiness of the device will require a new acceptance letter.
• Should the FHWA discover that the qualification testing was flawed, that in-service performance reveals unacceptable safety problems, or that the device being marketed is significantly different from the version that was crash tested, it reserves the right to modify or revoke its acceptance.
• You will be expected to supply potential users with sufficient information on design and installation requirements to ensure proper performance.
• You will be expected to certify to potential users that the hardware furnished has essentially the same chemistry, mechanical properties, and geometry as that submitted for acceptance, and that they will meet the crashworthiness requirements of FHWA and NCHRP Report 350.
• To prevent misunderstanding by others, this letter of acceptance, designated as number SS-116 shall not be reproduced except in full. As this letter and the supporting documentation which support it become public information, it will be available for inspection at our office by interested parties.
• The SPC4^tm load indicating fasteners are patented products and are considered "proprietary." The use of proprietary devices specified on Federal-aid projects, except exempt, non-NHS projects: (a) must be supplied through competitive bidding with equally suitable unpatented items; (b) the highway agency must certify that they are essential for synchronization with existing highway facilities or that no equally suitable alternative exists or; (c) they must be used for research or for a distinctive type of construction on relatively short sections of road for experimental purposes. Our regulations concerning proprietary products are contained in Title 23, Code of Federal Regulations, Section 635.411, a copy of which is enclosed.

Sincerely yours,

Carol H. Jacoby, P.E.
Director, Office of Safety Design

Enclosure