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FHWA Home / Safety / Roadway Departure / Safety Eligibility Letter

Safety Eligibility Letter WZ-104

DOT logo
U.S. Department
of Transportation
Federal Highway
Administration
400 Seventh St., S.W.
Washington, D.C. 20590

Refer To: HSA-10/WZ-95

Mr. Henry A. Ross, Director
Sales and Marketing
United Rentals Highway Technologies
880 North Addison Road
P.O. Box 7050
Villa Park, IL 60181-7050

Dear Mr. Ross:

Thank you for your letter of June 6 requesting Federal Highway Administration (FHWA) acceptance of your company’s High SafetyCor X-Tube Speed Limit Sign as crashworthy traffic control devices for use in work zones on the National Highway System (NHS). Accompanying your letter was a report of crash testing conducted by E-Tech Testing Services along with a video of the tests. You requested that we find this device 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.

A brief description of the device for which you are requesting acceptance follows:

High SafetyCor X-Tube Speed Limit Sign is a lightweight portable sign support made up of 44.5 mm square “X-Tube” PVC extrusions. The X-Tube uprights slip into 57.2 mm perforated tube steel sockets welded to a support base. The support base is made up of 50.8 mm x 50.8 mm x 4.8 mm thick steel angle iron.

The sign stand system features a two high arrangement of 914 mm wide rectangular signs made of 10.2 mm thick “SafetyCor”, an unfilled polypropylene copolymer corrugated plastic sheeting material. Each sign is bolted to the uprights with four 7.9 mm diameter ASTM A307 hex

fasteners and special 38.1 mm outside diameter rubber encased flat washers that increase the bearing area and help to prevent sign damage when the stands are stacked. When deployed the bottom of the lowest sign is nominally 1516 mm above the ground, and the overall height is
3662 mm to the top of the highest sign. As tested, the stands weighed 36.1 kg, and had four 18 kg sand bags as ballast. The four bags were placed at the ends of the supports.

Testing
Full-scale automobile testing was conducted on your company’s devices. Two stand-alone examples of the device 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 complete device as tested is shown in Enclosure 1.

The crash test is summarized in the table below:

Test Number 05-3721-013
Test Article High SafetyCor X-Tube Speed Limit Sign
Height to Bottom of Sign 1516 mm
Height to Top of Lights 3662 mm
Flags or lights None
Test Article Mass (each) 36.1 kg
Vehicle Inertial Mass 823 kg
Impact Speed, Head-on 101.1 km/hr
Impact Speed, 90 Deg. 97.7 km/hr
Velocity Change, Head-on 0.94 m/s
Velocity Change, 90 deg. 0.94 m/c
Vehicle crush Slight damage to bumper, grill, hood, windshield
Occupant Compart. Intrusion None
Windshield Damage General cracking, some broken glass in occupant compartment

Findings
Damage was limited to cosmetic sheet metal damage, with moderate cracking of the windshield. There were no holes or deformation of the windshield glass, nor was the damage extensive enough to impair the driver’s visibility. 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 as Test Level 3 devices on the NHS under the range of conditions tested, when proposed by a State.

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

Page last modified on June 2, 2009.
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