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.”  


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.


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


Weight of Tested Stand

44.5 kg

44.5 kg

Mounting heights

305 mm

305 mm

Flags? Lights?



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.


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:

Sincerely yours,

Michael S. Griffith
Acting Director, Office of Safety Design
Office of Safety