USA Banner
  U.S. flag
              An official website of the United States government Here's how you knowOfficial US Government Icon
              **Official websites use .gov**A **.gov** website belongs to an official government organization in the United States.
            Secure Site Icon
              **Secure .gov websites use HTTPS**
                  A **lock** ( A locked padlock ) or **https://** means you’ve safely connected to the .gov website. Share sensitive information only on official, secure websites. 
 U.S. Department of Transportation Icon United States Department of Transportation
 Search DOT
            Search
                    About FHWAFHWA Organization
                Headquarters Offices
                Field Offices
                Strategic Plan
                Business Opportunities
                Staff Directories
                Careers
                Highway History
                Contact UsProgramsAcquisition Management
                Civil Rights
                Federal Lands Highway
                Infrastructure
                Innovative Program Delivery
                Operations
                Planning, Environment, and Realty
                Policy
                Research, Development, and Technology
                Safety
                Browse by TopicsResourcesCore Highway Topics
                Federal Aid Essentials
                Automation
                Complete Streets
                Laws and Regulations
                Policy & Guidance Center
                Section 508
                Publications and Statistics
                Professional Development
                National Highway Institute
                Resource Center
                Accessibility Resource Library
                FHWA Research LibraryNewsroomPress Releases
                Speeches & Testimony
                Photos
                Videos
                Media ContactsMenu FHWA Highway Safety Programs Home
                        Safety
                        Roadway Departure Safety
                        Reduce Crash Severity
                        Hardware Eligibility Letters


            
            In This Section
        Roadway Departure Safety
                Strategic Approach
                                Strategic Plan
                Crash Emphasis Brochures
                Focused Approach
                Noteworthy Practices
                Partner Resources
                Keep Vehicles on the Road
                                Pavement Friction
                Horizontal Curve Safety
                Rumble Strips and Rumble Stripes
                Nighttime Visibility
                Provide for a Safe Recovery
                                SafetyEdge
                Clear Zones
                Reduce Crash Severity
                                Overview
                Hardware Eligibility Letters
                Focus on Reducing Rural Roadway Departures (FoRRRwD)
                                Overview
                All Public Roads
                Proven Countermeasures
                Systemic Approach
                Safety Action Plans
                FoRRRwD Resources
                
                Safety Eligibility Letter SS-166
  
  **Hardware Type:**
            Sign Supports, Mailboxes, and Delineator Posts
                          **Code:**
            SS-166
                          **Date:**
            12/07/2010
                          **Testing Criteria:**
            MASH
                          **Manufacturer:**
            North Texas Tollway Authority
                          **Device Description:**
            NTTA Short Sign Support
                          **View PDF:**
            ss166.pdf (281.25 KB)
    
    







1200 New Jersey Ave. S.E.
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 SupportType of system:
			Sign Supports — Reduced HeightTest Level:
			Manual for Assessing Safety Hardware (MASH) Test Level 3 (TL-3)Testing conducted by:
			Texas Transportation Institute (TTI)Task Force 13 Designator:
			SSP10a-bDate of request:
			July 22, 2010Date of completed package:
			November 23, 2010Initially acknowledged:
			July 29, 2010You 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.**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.

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.
	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,

			*/* Signature of Michael S. Griffith */*

			Michael S. Griffith
			Director, Office of Safety Technologies
			Office of Safety U.S. DEPARTMENT OF TRANSPORTATION

**Federal Highway Administration**

1200 NEW JERSEY AVENUE, SE

WASHINGTON, DC 20590

202-366-4000Subscribe to email updates
                    About
  

        
              About FHWA
                Careers
                Org Chart
                Staff Directories
                Work with UsPrograms
  

        
              Acquisition Management
                Civil Rights
                Federal Lands Highway
                Infrastructure
                Innovative Program Delivery
                Operations
                Planning, Environment, and Realty
                Policy
                Research, Development, and Technology
                SafetyPolicies, Rights, Legal
  

        
              About DOT
                Accessibility
                Budget and Performance
                Civil Rights
                FOIA
                Information Quality
                No FEAR Act
                Office of Inspector General
                Privacy Policy
                USA.gov
                Web Policies and Notices
                Web StandardsNews & Events
  

        
              Newsroom
                Press Releases
                Speeches & Testimony
                Media Contacts
                Connect with Us