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                Safety Eligibility Letter WZ-146
  
  **Hardware Type:**
            Work Zone Devices
                          **Code:**
            WZ-146
                          **Date:**
            03/25/2003
                          **Testing Criteria:**
            NCHRP 350
                          **Manufacturer:**
            United Rentals
                          **Device Description:**
            Low H-Stand with 48 inch sign
                          **View PDF:**
            wz146.pdf (4 MB)
    
    



March 25, 2003
Refer to: HSA-10/WZ-146
Mr. Henry Ross
United Rentals Highway
Technologies
880 North Addison Road
P.O. Box 7050
Villa Park,
Illinois  60181
Dear Mr. Ross:
This is in response to your letter of January 29, 2002,
requesting Federal Highway Administration (FHWA) acceptance of your company's
Low H-Stand Sign Stand with 48” sign, as crashworthy traffic control devices
for use in work zones on the National Highway System (NHS).  Accompanying your letter were reports of
crash testing conducted by E-Tech Testing Services and video 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 “INFORMATION: Crash Tested Work Zone
Traffic Control Devices.” This later
memorandum lists devices that are acceptable under Categories I, II, and III.
The
Low H-Stand Sign Stand with 48” sign features an “H” frame upright which
supports a 1219 mm diamond shaped aluminum sign that is 2.03 mm thick.  The sign is supported such that its bottom
tip is a nominal 305 mm above ground level. The support consists of two 44.5 mm square 12 gauge Unistrut Telespar
perforated steel tubing uprights. The
uprights are braced with two 44.5 mm square steel tubing crossbars. Each
crossbar is fastened to the uprights with four 9.5 mm diameter SAE J429 Grade 5
hex bolts. Each bolt uses a flat washer, lock washer, and hex nut.  Each upright slips into a 50.8 mm square
Telespar sleeve that is welded to a base tube. The base tubes are 44.5 mm square 11-gauge tubing. The material
specification for the steel tubing is ASTM A500 Grade B. The mass of each stand
was 44.5 kg and four 16 kg sand ballast bags were placed on the lower support
legs of each test article.
Testing
Full-scale automobile testing was conducted on your company'
stands.  Two stand-alone examples of the
devices were tested in tandem, one head-on and the next placed six meters
downstream turned at 90 degrees, as called for in our guidance memoranda.  The tests are summarized in the table below.
Low H-Stand Sign Stand with 48” signTest Number
Test 05-1640-001Sign Stand Tested
Head On
PerpendicularWeight of Tested Stand
44.5 kg
44.5 kgMounting heights
305 mm
305 mmFlags? Lights?
None
NoneMass of Test Vehicle
818 kgImpact Speed
100.4 km/h
90.9 km/hVelocity Change
2.64 m/s
2.64 m/sExtent of contact
Slight damage to
  bumper and hoodWindshield Damage
Contact, no damage
No contact*Other notes
No deformation of
  the occupant compartment* Following the impact with the head-on sign and stand, the
test article remained on the vehicle. The film of the impact with the perpendicular stand shows that the test
vehicle's bumper accelerated the test article with little, if any, tendency for
the test article to bend towards the windshield. Thus, it appears that the first sign did not compromise the
results of the impact with the second sign. We attribute the rigidity of the stand in the perpendicular orientation
to the presence of the two crossbars, which led to successful performance.
Findings
Damage was limited to cosmetic damage to the bumper, grille,
and hood.  The vehicle velocity change
was within the “desirable” range for crash-tested work zone traffic control
devices.  The results of the testing met
the FHWA requirements and, therefore, the sign stand described above and
detailed in the enclosed drawings 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, or 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-146 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.
The United Rental
traffic control devices may include
patented components and if so are considered "proprietary." The use of proprietary work zone traffic
control devices in Federal-aid projects is generally of a temporary
nature.  They are selected by the
contractor for use as needed and removed upon completion of the project.  Under such conditions they can be presumed
to meet requirement "a" given below for the use of proprietary
products on Federal-aid projects.  On
the other hand, if proprietary devices are specified for use on Federal-aid
projects, except exempt, non-NHS
projects, they: (a) must be supplied through competitive bidding with equally suitable unpatented items; (b) the highway
agency must certify that they are essential for synchronization with 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,
a copy of which is enclosed.Sincerely yours,
Michael S.
Griffith
Acting
Director, Office of Safety Design
Office
of Safety
Enclosures U.S. DEPARTMENT OF TRANSPORTATION

**Federal Highway Administration**

1200 NEW JERSEY AVENUE, SE

WASHINGTON, DC 20590

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