U.S. Department

of Transportation 400 Seventh St., S.W.

Federal Highway Washington, D.C.

20590

Administration

Refer to: HSA-10/WZ-99

Mr. Grant Dicke

Dicke Tool Company

1201 Warren Avenue

P.O. Box 518

Downers Grove, IL 60515

Dear Mr. Dicke:

Thank you for your letter of August 27 requesting Federal Highway Administration (FHWA)

acceptance of your company’s DF-4503 and SLIP-60 portable sign systems as crashworthy traffic

control devices for use in work zones on the National Highway System (NHS). Accompanying

your letter was a preliminary report of crash testing conducted by Midwest Roadside Safety

Facility 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.”

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 devices follows:

1. (Systems 56 and 57, Test No. D-29) DF-4503 Stand - A heavy duty, double torsion spring

mounted portable sign support with a 1219 x 1219 mm sign mounted at a height of 1518 mm

from the ground and with three wood-staffed flags at a height of 3778 mm. This stand

supported a RUR48 reflective vinyl roll up sign. Tested at both 90 degrees and head-on.

2. (Systems 60 and 61, Test No. D-31) SLIP-60 Stand. A rigid mounted portable sign support

with a 1219 x 1219 mm sign mounted at a height of 1613 mm from the ground. This stand

features a three-bolt slip base mechanism to enhance performance. It supported a 2.00 mm

thick aluminum sign. Tested at both 90 degrees and head-on with an EMPCO type “B” light

mounted to the type of the vertical mast. Height to top of light 3473 mm.
2

3. (Systems 62 and 63, Test No. D-32) SLIP-60 Stand. A rigid mounted portable sign support

with a 1219 x 1219 mm sign mounted at a height of 1638 mm from the ground. This stand is

the same as the SLIP- 60 tested as systems 60 and 61 except that no warning light was attached

to the top supported a 2.00 mm thick aluminum sign. Tested at both 90 degrees and head-on.

Testing

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

examples of the device were tested in tandem, one turned 90 degrees and the next placed 

six meters downstream struck head-on, 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 D-29 D-31 D-32

Test Article DF-4503 SLIP-60 SLIP-60

Sign 1219 x 1219 mm

roll up

1219 x 1219 mm

2 mm aluminum

1219 x 1219 mm

2 mm aluminum

Height to Sign Bottom 1518 mm (60 in) 1613 mm (60 in) 1651 mm (65 in)

Height to Sign Top 3239 mm 3277 mm 3300 mm (130 in)

Flags or lights With flags Empco Light None

Test Article Mass 20.5 kg 32 kg 30.6 kg

Total Mass of Ballast none 250 kg 250 kg

Vehicle Inertial Mass 897 kg 897 kg 883 kg

Impact Speed, Head-on 104.5 km/hr 88.9 km/hr 97.8 km/hr

Impact Speed, 90 Deg. 107.7 km/hr 107.8 km/hr 101.5 km/hr

Velocity Change* 0.89 m/sec 5.25 m/sec 1.02 m/sec

Vehicle crush Minor cracks,

scrapes on bumper

and roof

Minor damage to

bumper and lights

Minor roof

deformation

Occupant Compart. 

Intrusion

None None None

Windshield Damage None None None

* Velocity change of vehicle was measured after striking both test articles. In test D-30 the

brakes malfunctioned between impacts so the “velocity change” shown above does not reflect the

action of the test article. 

Findings

Damage was limited to dents on the bumper, grill, hood, and roof. There was no windshield

damage nor passenger compartment intrusion due to the test articles. 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 on the NHS under the range of conditions

tested, when proposed by a State.
3

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-99 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.

Dicke Tool sign stands 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 L. Halladay

Acting Program Manager, Safety 

Enclosure

FHWA:HSA-10:NArtimovich:tm:x61331:11/16/01

File: WZ99-DickeNov01Fin.wpd 

cc: HSA-10 (Reader, HSA-1; Chron File, HSA-10;

 N. Artimovich, HSA-10)