Refer to: HSA-10/WZ-130

Mr. David Stoudt 

Sign Up Corporation 

P.O. Box 14624 

Portland, Oregon 97293 

Dear Mr. Stoudt: 

Thank you for your letter of June 14, 2002, requesting Federal Highway Administration 

(FHWA) acceptance of your company=s X-CELL 48 HDL tall portable sign stands 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 and a 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.” You provided additional information at our request via a facsimile message on 

December 12, 2002. 

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 brief description of the devices follows: 

The X-CELL 48 HDL Sign Stand is a portable sign system featuring a spring loaded upright 

support and a 1219 mm x 2 mm thick diamond shaped aluminum sign. The sign stand has four 

legs made of 25.4 mm square 2 mm wall tubing. The tips of the legs are rubber capped and form 
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a 2235 mm by 1321 mm base pattern. The material specification is ASTM A500/A513 Grade A 

for all ERW (electronic resistance welded) steel square tubing used in the sign support. Each leg 

is attached to an “X-CELL” assembly which spring loads the sign support upright. 

The X-CELL assembly in turn supports a sign mounting stem “socket” made from 31.8 mm 

square 2.4 mm wall tube. A 25.4 mm square 2 mm wall steel tubing “center mast” is locked into 

the stem by a spring detent pin. A 19.1 mm square 1.6 mm wall steel tubing “upper mast” is 

locked into the stem by a spring detent pin. The sign is mounted to the mast with two sliding 

“rigid sign clamps.” Each clamp has two 9.5 mm carriage bolts with wing nuts used to clamp 

down on the sign corner. The clamps are secured in position on the mast with a thumbscrew. 

The lower rigid sign clamp supports the bottom of the sign 1626 mm above ground level. A flag 

holder, made of two 20 gage steel plates formed and spot welded together, completes the top of 

the mast. Three 457 mm square vinyl fabric flags with wooden dowels were attached to the top 

of the support. 

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 18-7222-001 

Test Article X-CELL 48 HDL Sign Stand with 2 mm Aluminum Sign 

Height to Bottom of Sign 1626 mm 

Height to Top of Sign 3350 mm 

Flags or lights Three flags on wood dowels 

Test Article Mass (each) 28.1 kg, ballasted with four 16 kg sand bags 

Vehicle Inertial Mass 820 kg 

Impact Speed, Head-on 101.1 km/hr 

Impact Speed, 90 Deg. 97.5 km/hr 

Velocity Change, Head-on 1.00 m/s 

Velocity Change, 90 deg. 1.00 m/s 

Vehicle crush None, slight cosmetic damage only 

Occupant Compart. Intrusion None 

Windshield Damage No contact by sign nor stand 
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Findings 

Damage was nonexistent in this impact as the mast separated from the base and the sign rotated 

over the vehicle in both impacts. Velocity changes were well below the maximum and within 

the “desirable” range. The results of the testing met the FHWA requirements and, therefore, the 

portable sign stand 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-130 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 X-CELL 48 HDL Sign Stand 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 
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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, 

Harry W. Taylor 

 Acting Director, Office of Safety Design 

Enclosure 

 
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. 

ENCLOSURE 2