U.S. Department 

Of Transportation 

Federal Highway 

Administration

400 Seventh St., S.W. 

Washington, D.C. 20590 

November 28, 2000 

Refer to: HSA-1/LS-49 

Mr. John L. Hill, III 

UTD Inc. 

10242 Battleview Parkway 

Manassas, VA 20109-2336 

Dear Mr. Hill: 

Thank you for your letter of September 22 requesting Federal Highway Administration 

(FHWA) acceptance of your company’s “UTD Safety Link” as a breakaway mechanism 

for utility pole guy wires for use on the National Highway System (NHS). Accompanying 

your letter was a report from Texas Transportation Institute and videos of the crash tests. 

You requested that we find guy wires using your company’s Safety Link 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 the supports 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’ (AASHTO) Standard 

Specifications for Structural Supports for Highway Signs, Luminaries and Traffic 

Signals. 

The UTD Safety Link consists of a threaded steel rod inside a two-piece outer cylinder. 

One end of the outer cylinder is anchored to the ground, while one end of the threaded 

rod protrudes through the top of the outer cylinder and attaches to the guy wire. The 

threaded rod is constrained at the joint between the two pieces of the outer cylinder. 

When the link is struck by an errant vehicle, the two-piece outer cylinder bends at the 

joint. This increases the tension in the threaded rod until it fails, releasing the guy wire 

connection to the ground. The two-pieces of the outer cylinder remain connected to each 

other by external chains or internal cables while the threaded rod is pulled out by the guy 

wire. 

There were four varieties made during the development of the link. 
A: Single internal cable loop 

B: Chain welded to two sides of link 

C: Two internal cable loops 

D: Four independent internal strands of wire rope 

Testing 

Full-scale automobile testing was conducted on your company’s devices. The mass of the 

test vehicle was 820 kg in all tests. The complete devices as tested are shown in the 

Enclosure 1. 

Test # NCHRP 

350 

Speed Version Article Occup. 

Speed 

Delta V 

1 Test 3-60 33.1 A Light Link No 

Contact 

0.55 

2 Test 3-61 96.6 A Light Link No 

Contact 

0.22 

3 Test 3-60 34.2 B Light Link No 

Contact 

0.33 

4 Test 3-61 94.7 B Light Link 1.3 1.1 

5 Test 3-60 97.4 B Double 

Link 

No 

Contact 

0.81 

6 Test 3-60 31.7 B Double 

Link 

No 

Contact 

0.1 

7 Test 3-60 35.9 C Improved No 

Contact 

0.58 

8 Test 3-61 101.5 C Improved 1.5 0.83 

9 Test 3-61 102.1 D Improved 1.6 0.50 

Speed: Actual impact speed of the test vehicle. Units are kilometers per hour. 

Occup. Speed: The Occupant Impact Speed is the speed at which a theoretical front seat 

occupant will contact the windshield. Units are meters per second. 

Delta V: Speed change of the test vehicle before and after contacting test article. Units 

are meters per second. 

Light Link: refers to a single guy and link device. 

Double Link: refers to two guys to the pole attached to a single point on the ground. Each 

guy was fitted with a Safety Link. 

Findings 

Damage was limited to denting of the bumper and hood, with windshield contact 

occurring in only two tests. In one of those tests there was localized cracking that would 

not interfere with the driver’s ability to see, and no damage at all in the other test. 

Velocity changes were all within acceptable limits, and the only stub remaining was the 

lower half of the Safety Link lying flat on the ground after each test. The results of tests 

met the FHWA requirements and, therefore, the four different designs (A through D) of 

the device, described above and shown in the enclosed drawings for reference, are 
acceptable for us as Test Level 3 devices on the NHS under the range of conditions 

tested, when proposed by a State. Design B (chain welded to two sides of the Link) is the 

preferred design. 

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 inservice performance reveals unacceptable safety problems, or that the device 

being marketed is significantly different form the version that was crash tested, it 

reserved 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 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 LS-49 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 “Safety Link” is or will be a patented product and is considered 

“proprietary.” The use of proprietary devices specified on Federal-aid projects, 

except exempt, non-NHS projects: (a) must be supplied through completive 

bidding with equally suitable unpatented items; (b) the highway agency must 

certify that they are essential for synchronization with existing highway facilities 

for 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, 

Frederick G. Wright, Jr. 

Program Manager, Safety 

Enclosure 
FHWA:HSA-1:Artimovich:tm:61331:11/27/00 

Cc: Reader: na: Chron File: HSA-1