U.S. Department

of Transportation 400 Seventh St., S.W.

Federal Highway Washington, D.C.

20590

Administration

Refer to: HSA-1\WZ-76

Mr. Ken Russell

Vice President

3D Specialties

1110 25th Avenue North

Fargo, ND 58107-1408

Dear Mr. Russell: 

Thank you for your January 26 and February 27 letters to Mr. Nicholas Artimovich of my staff 

requesting Federal Highway Administration (FHWA) acceptance of your company’s Type III

barricades as crashworthy traffic control devices for use in work zones on the National Highway

System (NHS). Accompanying your letters were photographs and drawings of the barricade,

which is nominally identical to the perforated square steel tube (PSST) barricade with aluminum

panels accepted in our letter WZ-55 to the State of Minnesota dated December 18, 2000. 

However, you requested that we find your company’s Type III barricade acceptable with two

significant modifications to the tested barricades. The first was to substitute “crossbuck panels”

for the horizontal rails and the second was to use (8 ft) long extruded panels. You requested

acceptance 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 tested Type III barricade follows:

A 1829 mm wide x 1528 mm deep x 1594 mm tall (72 x 60 x 62.75 in) Type III barricade. 

Vertical uprights are 38.13 mm x 38.13 mm x 3.07 mm wall x 1524 mm long (1.5 x 1.5 x 1/8 x 

60 in) galvanized steel Telespar posts. Horizontal legs are 44.67 mm x 44.67 mm x 1.93 mm 

wall x 1528 mm long (1.75 x 1.75 x 14 gage x 60 in) galvanized steel Telespar posts. To each 

leg is welded a 305 mm long (12 in) stub of like Telespar post. The uprights are inserted into 
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these stubs with no bolts or other fasteners being used. Three 230 mm wide x 1829 mm long (9 x

72 in) aluminum extruded panels are fastened to the uprights using 50.8 mm (1 in) corner bolts. 

When completed the uprights are 1257 mm (50 in) apart, out-to-out. A 20.4 kg (45 lb) bag of

sand was placed as ballast near the end of each leg. 

Modifications:

You requested two modification of the above barricade:

Modification A: Use of “crossbuck” section rails. These extruded aluminum sections are 229 mm

(9 in) wide and have four protrusions on the face that are 19 mm (3/4 in) deep. When we asked

the Midwest Roadside Safety Facility (MWRSF), (the organization that conducted the test on the

Minnesota Type III barricades) if they thought the crossbuck section would be an acceptable

alternative to the tested “dog bone” section, they replied:

“We have looked at the new proposed panel configuration and come up with

several potential concerns. First, with protruding horizontal ridges in the

panel members, the potential exists for the panels to slap down onto the

windshield with very concentrated forces when impacted at 0 degrees or

perpendicular to the vehicle travel. Second, since the geometrical section

properties likely differ from the dog-bone shape, there exists the potential

for different performance when the panel impacts the windshield at 90

degrees or parallel to the vehicle travel. In this case, the panels may not

buckle, collapse, or bend in a similar manner to those previously tested with

the dog-bone shape. The same could be stated if we were to change the

thickness of the dog-bone panels. Thus, with these differences in geometry,

I would recommend that the system be full-scale crash tested with an

actual car and windshield.”

We concur in their assessment, and deny the use of crossbuck panels unless crash tested.

Modification B: The use of 2438 mm (8 ft) long aluminum extruded panels.

The MWRSF tested the Type III barricade using 1829 mm (6 ft) long extruded aluminum 

“dog bone” panels. You requested the use of the identical design barricade using 2438 mm 

(8 ft) long aluminum panels of the same design. We have reviewed the MWRSF report and

conclude that the Type III barricade could be expected to perform in an acceptable manner if the

longer panels were used. There are two important limitations that we must add: 1) The

“extended” Minnesota Type III barricade may not be used with a sign panel unless tested, and 

2) The panels should not extend more than 0.3 m (approximately one ft) beyond the PSST

uprights. The crash test performance of the barricade with sign indicated that there could be a

real risk of significant windshield damage if these two limitations are not observed.

Findings

Damage of the MWRSF tests of the Minnesota Type III barricades was limited to cosmetic sheet

metal damage and minor windshield cracking. We expect that the same barricade using the 

2438 mm long panels will perform in a similarly acceptable manner. Therefore, the extended 

Type III barricade (Modification B) described above and shown in the enclosed drawings for
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reference is acceptable for use as Test Level 3 devices on the NHS under the range of conditions

tested and limitations noted above, when proposed by a State.

Please note the following standard provisions which 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-76 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.

Sincerely yours,

Frederick G. Wright, Jr.

Program Manager, Safety