400 Seventh St., S.W. 

Washington, DC 20590 March 16, 2007 

In Reply Refer To: 

HSSD/SS-146 

Mr. Jim Anderson 

Designovations, Inc. 

339 Wildwood Road 

Stillman Valley, IL 61084 

Dear Mr. Anderson: 

Thank you for your correspondence requesting Federal Highway Administration (FHWA) 

acceptance of your company’s SNAP’n SAFE TM round coupler breakaway system for sign 

supports for use on the National Highway System (NHS). Accompanying your request was a 

report from the Texas Transportation Institute. You requested that we find this device acceptable 

for use on the NHS under the provisions of the National Cooperative Highway Research 

Program (NCHRP) Report 350 “Recommended Procedures for the Safety Performance 

Evaluation of Highway Features.” 

Introduction 

Testing of your 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 Designovations, Inc., round coupler is a cast iron frangible coupling connecting a ground 

stub and the sign post. The coupler fractures upon impact at a predetermined scored line in the 

coupling, releasing the sign post from the ground stub. The coupler, shown in the attached 

drawing for reference, is fabricated of ASTM A48 Grey Iron, Class 35. The coupler is notched 

on each corner to an approximate depth of an eighth of an inch. This letter deals with SNAP’n 

SAFE TM round couplers designed for 2 3/8 inch diameter thin wall (16 Gauge) and other wall 

thicknesses up to and including schedule 40 (8 Gauge) round steel posts. 

Testing 

One sign support using the round coupler was crash tested and the summary of test results is 

enclosed. For the test DES P8, the coupler was installed approximately 3 inches above grade and 

was anchored inside a 3 foot long, 2 3/8 inch diameter steel tube embedded in the NCHRP 
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Report 350 Soft Soil. The coupler was used to support the 10 feet long, 2 3/8 inch diameter thin 

wall steel post. One 3 feet by 3 feet square sign panel was attached to the steel post 

approximately 7 feet above grade. 

Test # Speed Version Article OIS Delta V

400001-DES P8 34.5 km/hr 2.375 inch diameter Steel Tube None 0.1 m/s 

Occupant Impact Speed (OIS): Speed at which a theoretical front seat occupant will contact the 

windshield (in meters per second). 

Delta V: Speed change of the test vehicle (in meters per second). 

Findings 

Results of the test show the stub moved through the weak soil and deformed below the ground 

line, but the coupler still sheared as designed. Velocity change and deceleration are both within 

acceptable limits. There was no appreciable remains of the coupler left to protrude above the top 

of the stub, which had been installed such that the top of the stub would be at a height less than 4 

inches above the ground. The results of testing met the FHWA requirements and, therefore, the 

thin wall (16 Gauge) and other wall thicknesses up to and including schedule 40 (8 Gauge) round 

steel sign supports utilizing your SNAP’n SAFE TM round coupler as described above and shown 

in the enclosed drawing 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 the 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 the FHWA and 

the NCHRP Report 350. 

• To prevent misunderstanding by others, this letter of acceptance, designated as number 

SS-146, 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. 
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• The Designovations, Inc., SNAP’n SAFE TM Device is a patented product and is 

considered "proprietary.” When proprietary devices are specified by a highway agency

for use on Federal-aid projects they: (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. These 

provisions do not apply to exempt non-NHS projects. Our regulations concerning 

proprietary products are contained in Title 23, Code of Federal Regulations, Section 

635.411, a copy of which is enclosed. 

• This acceptance letter shall not be construed as authorization or consent by the FHWA to 

use, manufacture, or sell any patented device. Patent issues are to be resolved by the 

applicant and the patent owner. 

 Sincerely yours, 

John R. Baxter, P.E. 

Director, Office of Safety Design 

Office of Safety 

Enclosures