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                Safety Eligibility Letter WZ-223
  
  **Hardware Type:**
            Work Zone Devices
                          **Code:**
            WZ-223
                          **Date:**
            01/13/2006
                          **Testing Criteria:**
            NCHRP 350
                          **Manufacturer:**
            3D Specialties
                          **Device Description:**
            Minnesota Portable Sign Support
Minnesota
Portable Sign Support
Portable Sign Support
                          **View PDF:**
            wz223.pdf (218.93 KB)
    
    
Skip to contentSkip to contentUnited States Department of Transportation - Federal Highway AdministrationDOT logo
U.S. Department of Transportation
**Federal Highway Administration**
400 Seventh St., S.W.
Washington, D.C.  20590**January 13, 2006**


**Refer to: HSA-10/WZ-223**

Mr. Ken Russell
	3D Specialties 
	1110 25th Avenue North	
	Fargo, North Dakota  58102

Dear Mr.  Russell :
Thank you for your letter of December  9, 2005, requesting the Federal Highway Administration (FHWA) acceptance of  your company's modification to the Minnesota Portable Sign Support as a  crashworthy traffic control device for use in work zones on the National  Highway System (NHS). Accompanying your  letter was a drawing of the support that was found acceptable in the FHWA  letter WZ-133 dated November 26, 2002.  You requested that we find a modification to this portable sign stand  acceptable for use 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**
The FHWA guidance on crash testing  of work zone traffic control devices is contained in two memoranda. The first, dated July 25, 1997, titled "INFORMATION:  Identifying Acceptable Highway Safety Features," established four categories of  work zone devices: Category I devices are those lightweight devices which are  to be self-certified by the vendor, Category II devices are other lightweight  devices which need individual crash testing but with reduced instrumentation,  Category III devices are barriers and other fixed or heavy devices also needing  crash testing with normal instrumentation, and Category IV devices are trailer  mounted lighted signs, arrow panels, etc. for which crash testing requirements  have not yet been established. The  second guidance memorandum was issued on August 28, 1998, and is titled "INFORMATION:  Crash Tested Work Zone Traffic Control Devices." This later memorandum lists devices that are acceptable under  Categories I, II, and III. Our new  acceptance process was outlined in our memorandum "FHWA Hardware Acceptance Procedures – Category 2 Work Zone  Devices" dated November 11, 2005. The  Minnesota Department of Transportation (Mn/DOT) rigid panel portable sign  support is a stiffened perforated square steel tube "H-Footprint" device. You requested that a substitution for the  38.1 mm (1.5 inch) horizontal legs be allowed, using 50.8 mm (2.0 inch)  perforated square steel tube in either 12 gage or 14 gage steel.
A  description of the modified device follows:
Vertical upright masts are       44.5 mm (1.75 inch) square galvanized Telespar ASTM A-653 Grade 50 steel       tubing with 2.67 mm (0.105 inch) wall thickness and a length of 1524 mm       (60 inches.)
Outside vertical upright       tubing is 50.8 mm (2 inch) square galvanized Telespar ASTM A-653 Grade 50 steel tubing with 2.74       mm (0.108 inch) wall thickness and a length of 911 mm (33.875 inches.)
Horizontal legs are 50.8 mm       (2.0 inch) square galvanized Telespar ASTM A-653 Grade 50 steel tubing       with 12 gage or 14 gage wall thickness and a length of 1524 mm (60 inches.)
Vertical stubs from the       legs are 38.1 mm (1.5 inch) square galvanized Telespar ASTM A-653 Grade 50 steel tubing with 2.74       mm (0.108 inch) wall thickness and a length 305 mm (12 inches.) It is welded to the horizontal leg on       all four sides.
The outside vertical       upright tubes slide over the vertical uprights and the vertical portion of       the legs slide into the vertical upright masts with 7.9 mm (0.3125 inch)       diameter x 63.5 mm (2.5 inch) long       hex head S30400 threaded bolts used to fasten the masts and legs.
The solid, 2.74 mm (0.108       inch) aluminum sign panel was 1219 mm (48 inch) diamond shaped and       fastened to the stand with four 7.9 mm (0.3125 inch) x 63.5 mm (2.5 inch)       long hex head S30400 threaded bolts.
Height to bottom of sign:       335 mm (13.1875 inches) Height to top of outer tube 959 mm (37.74       inches). Height to the Warning Light bolt, 1,481 mm (58.3125       inches).
The legs have a mass of       10.7 kg (23.5 pounds) when 14 gage material is used, and 12.5 kg (27.6 pounds) when 12 gage       material is used. The panel, masts, outside tubes, and light have a mass       of 36.75 kg (81 pounds.) One 20 kg       (45 pound) sandbag may be placed at the end of each leg.**Testing and Findings**
The results of the Mn/DOT testing  met the FHWA requirements and the FHWA acceptance letter WZ-133 was  issued. We concur that your proposed  modification increases the strength of the legs without significantly  increasing the weight and would not adversely affect the performance of this  sign stand. Therefore, the modified  sign stand described above is acceptable for use 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 WZ-223 shall not be reproduced except in full. This letter, and the test documentation       upon which this letter is based, is public information. All such letters and documentation may       be reviewed at our office upon request.
This       acceptance letter shall not be construed as authorization or consent by       the FHWA to use, manufacture, or sell any patented device for which the       applicant is not the patent holder.       The acceptance letter is limited to the crashworthiness       characteristics of the candidate device, 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,

**/original signed by /**
John R. Baxter, P.E.
Director, Office of Safety Design
Office of Safety

Enclosure
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