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. 
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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” sign 

Test Number Test 05-1640-001 

Sign Stand Tested Head On Perpendicular 

Weight of Tested Stand 44.5 kg 44.5 kg 

Mounting heights 305 mm 305 mm 

Flags? Lights? None None 

Mass of Test Vehicle 818 kg 

Impact Speed 100.4 km/h 90.9 km/h 

Velocity Change 2.64 m/s 2.64 m/s 

Extent of contact Slight damage to bumper and hood 

Windshield 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: 
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• 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 
Sec. 635.411 Material or product selection. 

(a) Federal funds shall not participate, directly or indirectly, in payment for any premium or royalty on 

any patented or proprietary material, specification, or process specifically set forth in the plans and 

specifications for a project, unless: 

(1) Such patented or proprietary item is purchased or obtained through competitive bidding with equally 

suitable unpatented items; or 

(2) The State highway agency certifies either that such patented or proprietary item is essential for 

synchronization with existing highway facilities, or that no equally suitable alternate exists; or 

(3) Such patented or proprietary item is used for research or for a distinctive type of construction on 

relatively short sections of road for experimental purposes. 

(b) When there is available for purchase more than one nonpatented, nonproprietary material, 

semifinished or finished article or product that will fulfill the requirements for an item of work of a 

project and these available materials or products are judged to be of satisfactory quality and equally 

acceptable on the basis of engineering analysis and the anticipated prices for the related item(s) of work 

are estimated to be approximately the same, the PS&E for the project shall either contain or include by 

reference the specifications for each such material or product that is considered acceptable for 

incorporation in the work. If the State highway agency wishes to substitute some other acceptable 

material or product for the material or product designated by the successful bidder or bid as the lowest 

alternate, and such substitution results in an increase in costs, there will not be Federal-aid participation in 

any increase in costs. 

(c) A State highway agency may require a specific material or product when there are other acceptable 

materials and products, when such specific choice is approved by the Division Administrator as being in 

the public interest. When the Division Administrator's approval is not obtained, the item will be 

nonparticipating unless bidding procedures are used that establish the unit price of each acceptable 

alternative. In this case Federal-aid participation will be based on the lowest price so established. 

(d) Appendix A sets forth the FHWA requirements regarding (1) the specification of alternative types of 

culvert pipes, and (2) the number and types of such alternatives which must be set forth in the 

specifications for various types of drainage installations. 

(e) Reference in specifications and on plans to single trade name materials will not be approved on 

Federal-aid contracts.