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                Safety Eligibility Letter WZ-133
  
  **Hardware Type:**
            Work Zone Devices
                          **Code:**
            WZ-133
                          **Date:**
            11/26/2002
                          **Testing Criteria:**
            NCHRP 350
                          **Manufacturer:**
            MWRSF
                          **Device Description:**
            Rigid frame portable sign stand
                          **View PDF:**
            wz133.pdf (1.2 MB)
    
    



November 26, 2002
Refer to: HSA-10/WZ-133
Mr. Ron Faller
Midwest Roadside Safety
Facility
1901 “Y” Street, Bldg.
C
P.O. Box 880601
Lincoln, Nebraska  68588-0601
Dear Dr. Faller:
Thank you for your September 12, 2002, letter requesting
Federal Highway Administration (FHWA) acceptance of the Minnesota Department of
Transportation (DOT) temporary work zone sign stand as a crashworthy traffic control device for
use in work zones on the National Highway System (NHS).  Accompanying your letter was a report of
crash testing you conducted and a CD of the tests. You requested that we find
these devices 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 were those lightweight devices which could be
self-certified by the vendor, Category II devices were other lightweight
devices which needed individual crash testing, Category III devices were
barriers and other fixed or massive devices also needing crash testing, and
Category IV devices were trailer mounted lighted signs, arrow panels, etc.  The second guidance memorandum was issued on
August 28, 1998, and is titled AINFORMATION:
Crash Tested Work Zone Traffic Control Devices.”  This later memorandum lists devices that are acceptable under
Categories I, II, and III.
A description of the device follows:
The Minnesota DOT rigid panel portable sign support is a stiffened
perforated square steel tube “H-Footprint” device:
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 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 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 9.1 kg (10 pounds) and the panel, masts, outside
     tubes, and light have a mass of 36.75 lg (81 pounds.) One 20 kg (45 pound)
     sandbag was placed at the end of each leg.Testing
This crash-testing program used a hard-nosed bogie vehicle
of a mass larger than the standard 820C test vehicle.  There are significant constraints involved in using such a
non-standard testing device, some of which are:
The potential vehicle velocity change must be considered
insignificant.
The crush characteristics of an automobile bumper must not be
expected to have a significant affect on the trajectory of the test article.
The profile of the bogie vehicle must be configured to
replicate the outline of a production vehicle. The MWRSF bogie was configured
to replicate the outline of a Geo Metro, a vehicle commonly used in testing of
work zone devices.
No part of the test article may intrude into the windshield
area of the vehicle after impact.The two tests and their results summarized below were within
these constraints.
Stand-alone examples of the devices were tested in separate
tests, one head-on and one turned at 90 degrees, as called for in our guidance
memoranda.  The complete device, as
tested is shown in Enclosure 1.  The
crash test is summarized in the table below:
Test Number
MNSB-12
MNSB-13Test Article
Head-on
End-OnFlags or lights
One lightweight warning light on each standTest Article Mass (each)
45.8
  kg (91 pounds) plus ballastBogie Inertial Mass
974
  kg (2148 pounds)Impact Speed
97.5
  km/hr (60.6 mph)
98.8
  km/hr (61.4 mph)Approx. Velocity Change
10
  km/hr, 2.78 m/s
10
  km/hr, 2.78 m/sFindings
The rigid frame of these stands caused them to be pushed
ahead of the bogie, or knocked to one side. 
Neither showed any potential for approaching the windshield or causing
any other passenger compartment intrusion. 
The trajectory of the sign stands in these tests indicate that the bogie
vehicle, even though it was not within the specification range of an NCHRP
Report 350 820C test vehicle, was acceptable for establishing the
crashworthiness of the stands.  The
results of the testing met the FHWA requirements and, therefore, the devices
described above and shown in the enclosed drawings for reference are 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
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 FHWA
and NCHRP Report 350.
To
prevent misunderstanding by others, this letter of acceptance, designated as
number WZ-133 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.Sincerely yours,
Carol H. Jacoby,
P.E. 
Director,
Office of Safety Design
Enclosure U.S. DEPARTMENT OF TRANSPORTATION

**Federal Highway Administration**

1200 NEW JERSEY AVENUE, SE

WASHINGTON, DC 20590

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