Refer to: HSA-10/WZ-149

Ronald K. Faller, Ph.D., P.E. 

Research Assistant Professor 

Midwest Roadside Safety Facility 

University of Nebraska, Lincoln 

527 Nebraska Hall 

P.O. Box 880529 

Lincoln, Nebraska 68588-0529 

Dear Dr. Faller: 

This is in response to your letter of February 5, 2003, requesting Federal Highway 

Administration (FHWA) acceptance of the Michigan Department of Transportation’s 

Temporary Sign Stand as a crashworthy traffic control device for use in work zones on 

the National Highway System (NHS). Accompanying your letter were reports of crash 

testing conducted by the Midwest Roadside Safety Facility 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.” 

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 sign stand follows: 

(System Nos. 5 and 6) a 1,730-mm wide x 1,829-mm deep x 3,264-mm tall steel sign 

support with a 1,219-mm x 1,219-mm x 15.9-mm thick plywood diamond-shaped 

sign panel with reflective material mounted at a height of 1,540 mm from the ground 

to the bottom of the sign panel and with a lightweight “Empco-Lite” Type A warning 

light mounted at a height of 2,597 mm from the ground to the top of the warning light 

and with 15.88 kg of sandbags at the end of each leg. 
Testing 

A total of six devices were crash tested as part of the Michigan DOT program. System 

Nos. 1 and 2 were the original version of the stand which failed due to passenger 

compartment intrusion. System Nos. 3 and 4 were 12-foot long Type III barricades which 

also failed to meet the evaluation criteria. System Nos. 5 and 6 were the redesigned sign 

stand using stiffened masts, relocated warning light, revised sign-to-post fasteners, and 

the omission of the speed advisory plate. 

Full-scale automobile testing was conducted on the final design of the sign stand. Two 

stand-alone examples were tested in tandem, one oriented at 90 degrees to travel, and the 

next placed 60 feet downstream at a head-on orientation, as called for in our guidance 

memoranda. The successfully tested stand was modified from an earlier design that was 

tested in a prior crash test program. 

The tests are summarized in the table below. 

Michigan Temporary Sign Stand 

Test Number MI-3, System 5 MI-3, System 6 

Sign Stand Orientation 90 degrees (End-on) 0 degree (Head-on) 

Weight of Stand, Sign, Light 53.5 kg +/- 53.5 kg +/- 

Mounting heights 1540 mm 1540 mm 

Flags? Lights? Empco Lite Model 400 Empco Lite Model 400 

Mass of Sand Ballast One 31.75 kg bag at each end of each leg 

Mass of Test Vehicle 896 kg 

Impact Speed 101.0 km/hr 91.3 km/hr * 

Velocity Change 2.7 m/s n/a 

Extent of contact 95 mm roof crush 

Windshield Damage Spider cracking in upper right. No deformation or hole 

Other notes *Low speed is acceptable. 

Findings 

Damage was limited to the front end of the vehicle (bumper, grill, radiator), minor spider 

cracking of a portion of the windshield, and 95 mm of roof deformation (from the corner 

of the 90-degree orientation sign panel, in the vicinity of the warning light.) The velocity 

change caused by System 5 (90-degree orientation) slowed the vehicle enough to drop it 

below the tolerance for a 100 km/hr test. The possibility of this occurring was known 

when FHWA established the recommendation to hit two examples of the device on the 

same run of the test vehicle. We concur in your analysis that the damage would not have 

been significantly greater had System 6 been struck at 100 km/hr. The results of the 

testing met the FHWA requirements and, therefore, the Michigan Temporary 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: 
• Our acceptance is limited to the crashworthiness characteristics of the devices and 

does not cover their structural features, or 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 or the Michigan DOT will be expected to supply potential users with sufficient 

information on design and installation requirements to ensure proper performance. 

• You or the Michigan DOT should supply information to potential users that would 

allow them to certify 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 by the 

FHWA as number WZ-149 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, 

Michael S. Griffith 

 Acting Director, Office of Safety Design 

Office of Safety 

Enclosures