1200 New Jersey Ave., SE

Washington, D.C. 20590

December 7, 2010

In Reply Refer To:

HSSI/SS-166

Mr. Eric Hemphill, P.E.

Assistant Director of Maintenance Operations

North Texas Tollway Authority

P.O. Box 260729

Plano, TX 75026

Dear Mr. Hemphill:

This letter is in response to your request for the Federal Highway Administration (FHWA) 

acceptance of a roadside safety system for use on the National Highway System (NHS).

Name of system: North Texas Tollway Authority (NTTA) 

Short Sign Support 

Type of system: Sign Supports – Reduced Height

Test Level: Manual for Assessing Safety Hardware (MASH) Test 

Level 3 (TL-3)

Testing conducted by: Texas Transportation Institute (TTI)

Task Force 13 Designator: SSP10a-b

Date of request: July 22, 2010

Date of completed package: November 23, 2010

Initially acknowledged: July 29, 2010

You requested that we find this system acceptable for use on the NHS under the provisions of the 

American Association of State Highway and Transportation Officials’ (AASHTO) Manual for 

Assessing Safety Hardware (MASH).

Decision:

The following device was found acceptable. Details are below:

• NTTA Short Sign Support for WRONG WAY signing.
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Requirements

Roadside safety devices should meet the guidelines contained in the AASHTO MASH. The 

FHWA memorandum, “Identifying Acceptable Highway Safety Features” of July 25, 1997,

provides further guidance on crash testing requirements of longitudinal barriers. 

Description

The NTTA Short Sign Support is a post and sign system supporting a 2-ft high by 3-ft wide 

WRONG WAY sign mounted 2 ft above ground. The sign panel is 0.11 inch thick aluminum 

and is mounted on a single 60-inch long post consisting of a 2 3/8-inch diameter pipe support 

with a wall thickness of 13 gauge (0.092 inch). The pipe support is embedded in a 12 inch 

diameter by 30 inch deep concrete footing using a Poz-Loc wedge and socket device. Details of 

the system are shown in Enclosures 1 and 2. The sign is intended for use on main lane freeway 

exit ramps to alert drivers of wrong way movements. 

Crash Testing

Test 3-61 was conducted on the sign support by TTI according to the MASH guidelines. The 

1100C vehicle impacted the test article at 64.3 mph at 0 degrees. The testing was conducted 

with the test vehicle hitting the back of the sign post, as this orientation is likely to be the most

common type of impact experienced in service, given that the majority of vehicular traffic 

towards the sign will be travelling the correct direction, leaving the highway. The crash test was 

evaluated in accordance with the criteria presented in the MASH. The test article successfully 

passed test 3-61. The NTTA short sign support yielded to the 1100C vehicle. In testing the sign 

panel separated from the post, vaulted, but did not penetrate the occupant compartment. The 

longitudinal and lateral Occupant Impact Velocities were 2.6 ft/sec and 0.3 ft/sec respectively 

which were below the MASH preferred value of 10 ft/sec. The maximum longitudinal and 

lateral Occupant Ridedown Accelerations were -0.3G and -0.2G respectively. Both values were 

well below the MASH preferred value of 15.0G. Enclosure 3 shows the results of the test 

results. 

Findings

According to the MASH, test designations 3-60, 3-61, and 3-62 are to be conducted for approval 

of TL-3 for support structures. Test 3-60 which is a low speed impact test with a passenger car 

and test 3-62 which is a high speed impact test with a pickup truck were not performed. In your 

letter you requested that tests 3-60 and 3-62 be waived. You also requested that the TL-2 

acceptance be granted. We concur with these requests as explained below.

Test 3-62 can be waived on the grounds that (1) the post will likely yield in the same manner that 

was observed in test 3-61 with a passenger car; (2) given the height of the hood of most pickup 

trucks, it will be unlikely that the sign panel can hit the windshield of a pickup truck; and (3) the 

Occupant Impact Velocities and Occupant Ridedown Accelerations were well below the 

preferred limits and those are not expected to be much larger for a pickup truck. 
3

Low- speed tests including Test 3-60 and tests required for TL-2 approval are waived based on 

the performance of the test article observed in the video of the high speed test and the fact that 

the low speed tests have generally been to verify that the breakaway features perform as 

intended. In addition, the wedge and socket system has been tested an accepted at both low and 

high speeds as a full-height sign support.

In test 3-61, the sign panel separated from the post once the test vehicle impacted the sign. 

Therefore, use of the sign system should give consideration to proximate pedestrian activity. 

In the context of the comments provided, the system described in the requests above and detailed 

in the enclosed drawings is acceptable for use on the NHS under the range of conditions tested, 

when such use is acceptable to a highway agency.

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

• This acceptance is limited to the crashworthiness characteristics of the systems 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 system 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 system being marketed is 

significantly different from the version that was crash tested, we reserve the right to 

modify or revoke our 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 it will meet the crashworthiness requirements of the FHWA and 

MASH. 

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

SS-166 and shall not be reproduced except in full. This letter and the test documentation 

upon which it is based are public information. All such letters and documentation may be 

reviewed at our office upon request. 

• The Poz-Loc Base is a patented product and considered proprietary. If proprietary 

systems are specified by a highway agency for use on Federal-aid projects, except 

exempt, non-NHS projects, (a) they must be supplied through competitive bidding with 

equally suitable unpatented items; (b) the highway agency must certify that they are 

essential for synchronization with the 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.
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• This acceptance letter shall not be construed as authorization or consent by the FHWA to 

use, manufacture, or sell any patented system for which the applicant is not the patent 

holder. The acceptance letter is limited to the crashworthiness characteristics of the 

candidate system, and the FHWA is neither prepared nor required to become involved in 

issues concerning patent law. Patent issues, if any, are to be resolved by the applicant.

 Sincerely yours,

Michael S. Griffith

 Director, Office of Safety Technologies

 Office of Safety

3 Enclosures