U.S. Department

of Transportation 400 Seventh St., S.W.

Federal Highway Washington, D.C.

20590

Administration

Refer to: HSA-10/WZ-91

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 Low H-Stand sign stand as a crashworthy traffic control device

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 test. 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:

The Low H-Stand is a portable sign stand featuring an “H-Frame” upright support. The support

consists of two 38.1 mm square 12 gauge Unistrut Telespar perforated steel tubing uprights. The

uprights are braced with two 38.1 mm square 11 gague steel tubing crossbars. Each crossbar is

fastened to the uprights with four 9.5 mm diameter ASTM A307 hex bolts. Each bolt uses a flat

washer, lock washer, and hex nut. Each upright slips into a 44.5 mm square 12 gauge Telespar

sleeve which is welded to a base tube. The base tubes are 44.5 mm square 11 gage tubing. The

material specification for the steel is ASTM A500 Grade B. 
2

The Low H-Stand system features a 915 mm square, 1.8 mm thick aluminum sign which is

fastened to the uprights with four 9.5 mm diameter ASTM A307 hex fasteners and flat washers,

lock washers, and nuts. When deployed the bottom of the sign is nominally 533 mm above the

ground. The mass of the stand with sign was 29.1 kg. Four 16 kg sand bags were draped over the

ends of the base tubes.

Testing

Full-scale automobile testing was conducted on your company’s devices. Two

stand-alone examples of the device were tested in two separate tests, one

head-on and one with the device turned at 90 degrees. The complete devices

as tested are shown in Enclosure 1.

The crash test is summarized in the table below:

Test Number 05-3721-008 05-3721-009

Test Article Low H-Stand system

Height to Bottom of

Sign

533 mm

Height to Top of Sign 1827 mm

Flags or lights None

Test Article Mass

(each)

29.1 kg

Vehicle Inertial Mass 817 kg 819 kg

Impact Speed, Head-on 99.0 km/hr -

Impact Speed, 90 Deg. - 97.7 km/hr

Velocity Change, Headon1.5 m/s -

Velocity Change, 90

deg.

- 3.1 m/s

Vehicle crush Moderate denting to

bumper, grille, and

hood

Moderate denting to

bumper, grille, and

hood

Occupant Compart.

Intrusion

None None

Windshield Damage None None

Findings

Damage was limited to moderate denting of the bumper, grille, and hood, but there was no contact

with the windshield. 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:
3

! 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-91 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.

! United Rentals work zone 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,

Frederick G. Wright, Jr.

Program Manager, Safety 

Enclosure

FHWA:HSA-10:NArtimovich:tm:x61331:09/24/01