1200 New Jersey Avenue, SE. 

Washington, DC 20590 November 14, 2008 

In Reply Refer To: HSSD/B-182 

Mr. Scott K. Rosenbaugh 

Research Associate Engineer 

Midwest Roadside Safety Facility 

University of Nebraska-Lincoln 

527 Nebraska Hall 

Lincoln, Nebraska 38588-0529 

Dear Mr. Rosenbaugh: 

This letter is in response to your request for the Federal Highway Administration (FHWA) 

acceptance of a roadside safety system for use on the National Highway System (NHS). 

 Name of system: Vertical-Faced, Concrete Median Barrier Incorporating 

 Head Ejection Criteria 

 Type of system: Concrete Median Barrier 

 Test Level: NCHRP Report 350 TL 5 & MASH-08 TL 5 

 Testing conducted by: Midwest Roadside Safety Facility 

 Date of request: February 27, 2008 

 Date of completed package: October 14, 2008 

You requested that we find this system 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” and the proposed 

American Association of State Highway and Transportation Officials’ Manual for Assessing 

Safety Hardware 2008 (MASH-08). 

Requirements

Roadside safety systems should meet the guidelines contained in the NCHRP Report 350, 

"Recommended Procedures for the Safety Performance Evaluation of Highway Features". 

FHWA Memorandum “ACTION: Identifying Acceptable Highway Safety Features” of 

July 25, 1997, provides further guidance on crash testing requirements of longitudinal barriers. 

You have also chosen to anticipate the adoption of MASH-08, an option that FHWA has offered 

with the understanding that additional testing may need to be done if changes to the test criteria 

are made before MASH-08 is formally adopted. 

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Description 

This concrete median barrier is intended to safely redirect vehicles ranging from small cars to 

fully-loaded tractor trailers, while (1) maximizing stability in passenger vehicles by limiting 

wheel climb and roll, (2) addressing occupant safety by limiting peak impact forces, 

(3) preventing head slap, and (4) providing an economical alternative to existing concrete barrier 

designs. The profile of the upper 8 inches of the barrier is set back to accommodate a “head 

ejection envelope” which was determined through an analysis of previous full-scale crash tests 

involving passenger vehicles impacting vertical-faced barriers and other rigid concrete barriers. 

The geometry of this setback directly applies only to rigid barriers with a vertical or near vertical 

face, and for belted occupants meeting the measurements of the Hybrid III 50 and 95 percentile 

male dummies. 

The final barrier cross section design is shown in the drawings which are enclosed for reference. 

Also shown is the barrier end section with a footer whose function is to provide sufficient torsion 

resistance to match the overturning moment of the end section.

Crash Testing 

Full-scale crash testing was conducted with a tractor-trailer rig having a test inertial weight of 

36,154 kg (79,538 pounds) following NCHRP Report 350 Test 5-12 and MASH-08 Test 5-12. 

The enclosed test data summary page shows the impact velocity was 84.9 km/hr (55.7 mi/hr) at 

an angle of 15.4 degrees. During the impact, the maximum roll angle of the truck was 

22.8 degrees. Although the dynamic deflection of the barrier was negligible (38 mm, or about 

1.5 inches), the “working width” considering the incursion of the box over the top of the barrier 

was 1894 mm (75 inches). 

Findings 

The concrete median barrier adequately contained and redirected the vehicle without permanent 

displacements of the barrier. Vehicle roll, pitch, and yaw angular displacements were deemed 

acceptable, because they did not adversely influence occupant risk safety criteria nor cause 

rollover. After collision, the vehicle rode down the face of the barrier and did not intrude into 

adjacent traffic lanes. Thus, the vehicle’s exit angle was less than 60 percent of the impact angle. 

Therefore, test TL5CMB-2 conducted on a concrete median barrier was determined to be 

acceptable according to the TL-5 safety performance criteria found in NCHRP Report 350. Note, 

the test also satisfies all evaluation criteria for test 5-12 found in MASH-08. 

Therefore, the system described above and detailed in the enclosed drawings is acceptable for 

use on the NHS under the range of conditions tested, when such use is acceptable to a highway 

agency. 

As NCHRP Report 350 does not have mandatory evaluation criteria regarding vehicle occupants 

contacting the hardware outside of the occupant compartment, this letter is limited to accepting 

the performance as a median barrier to contain and redirect vehicles, with no implication that 

head ejection criteria is a requirement. However, MASH-08 does identify the safety risk 

involved with occupants extending out of the vehicle and coming into direct contact with the test 

article in Section 4.2.1.5, Paragraph 2. This guidance recommends that dummies are to be 

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placed in the front seat on the impact side of passenger vehicles during tests of longitudinal 

barriers taller than 33 inches. Although a passenger vehicle test was not performed, the barrier 

geometry was designed to prevent such occupant-barrier contact.

Please note the following standard provisions that apply to FHWA letters of acceptance: 

• This acceptance is limited to the crashworthiness characteristics of the systems 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 system 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 system being marketed is 

significantly different from the version that was crash tested, we reserve the right to modify 

or revoke our 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 it will meet the crashworthiness requirements of the FHWA and the NCHRP 

 Report 350. 

• To prevent misunderstanding by others, this letter of acceptance is designated as number 

 B-182 and shall not be reproduced except in full. This letter and the test documentation upon 

which it is based are public information. All such letters and documentation may be 

reviewed at our office upon request. 

• This acceptance letter shall not be construed as authorization or consent by the FHWA to use, 

manufacture, or sell any patented system for which the applicant is not the patent holder. 

The acceptance letter is limited to the crashworthiness characteristics of the candidate 

system, and the FHWA is neither prepared nor required to become involved in issues 

concerning patent law. Patent issues, if any, are to be resolved by the applicant. 

Sincerely yours, 

 David A. Nicol 

 Director, Office of Safety Design 

 Office of Safety 

Enclosures 

FHWA:HSSD:NArtimovich:tb:x61331:11/14/08 

File: s://directory folder/nartimovich/B182MWRSFheadEjectionBArrierTL5-S_V2.doc 

cc: HSSD (Reader, HSA; Chron File, HSSD; N.Artimovich, HSSD; 

 MMcDonough, HSSD) 

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