In Reply Refer To:HSA-10/B-145

April 6, 2006

In Reply Refer To:HSA-10/B-145

Ronald K. Faller, Ph.D., P.E.
Midwest Roadside Safety Facili ty
University ofNebraska, Linco ln
527 Nebraska Hall
P.O. Box 880529
Lincoln, Nebraska 68588-0529

Dear Dr. Faller:

Thank: you for your letter of December 16, 2005. requesting the Federal Highway Administration (FHWA) acceptance ofa Test Level 5 (TL- 5) Bridge Rail developed in cooperation with the Nebraska Department of Roads. Accompanying your letter were reports of crash testing you conducted at the Midwest Roadside Safety Facili ty along with video and photographic documentation of the test s. You requested that we find this railing acceptable for use on the National Highway System (NHS) under the provisions of the National Cooperative Highway Research Program (NCHRP) Report 350 "Recommended Procedures for the Safely Performance Evaluation of Highway Features."

Introduction
The FHWA guidance on crash testing of roadside safety hardware is contained in a memorandum dated July 25, 1997, lilled "INFORMATION: Identifying Acceptable Highway Safety Features."

A briefdescription of the barrie r follows:

The 121-ft 6-in.long, aesthetic post and beam concrete bridge rail con sisted of a "ribbed" reinforced concrete beam 14-in. wide by 3D-in. deep with a 42-in. top mounting height which was cast in place with a 2-in. overhang on the front face of the posts parallel to the roadway and flush with the backs ide of the posts. The two " ribs" extend l-½ in. from the face of the beam. Both upstream and downstream edges of the posts were tapered back 2 in. from the face of the post to minimize tire snagging of passenger vehicles. Fifteen bridge posts, measuring 1O.5-in. wide by 30-in. long by 12-in. high. were used to support the bridge rail. Bridge posts were spaced 8 ft - 6 in. on centers along the length of the bridge railing. The concrete used for the bridge rail and posts had a minimum compressive strength of 5.000 psi.

A minimum concrete cover of 2 in. was used for all the rebar placed within the bridge rail and posts. All steel reinforcement in the bridge rail and posts was Grade 60 epoxy-coated rebar. The bridge rail and post dimensions, including reinforcement details. arc shown in the enclosed drawings for reference.

Testing
Full-scale tractor-semi trailer testing was conducted on the barrier. The report explai ns that concrete barriers with similar features have been successfully crash tested with 820C and 2000P vehicles . We concur that the single TL-5 test is the only one requ ired to qualify this barrier.

Findings
The test showed that the aesthetic open concrete bridgerail adequately contain ed and redirected the vehicle with controlled lateral displacements of the rail. There were no detached elements or fragmen ts which showed pote ntial for penet rating the occupant compartment nor presented undue hazard to other tra ffic. There were no deformations or intrusions into the passenger compartment that cou ld have caused serious injury. The test vehicle did not penetrate or roll over the barrier, and it remained upright without intruding into adjacent traffic lanes. Vehicle roll, pitch, and yaw were good to moderate. As shown above, while the dynamic deflection was about 11 in., the Working Width (deflect ion plus vehicle overhang plu s width of the rail system) was slightly over 6 ft.

The results of the testing met the HCHRP Report 350 requirements and, therefore, the device described above and detailed in the enclosed drawings is acceptable for use on the NHS as a TL-5 bridge rail, under the range ofconditions tested, when proposed by a State.

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

• Our acceptance is limited to the crashworthiness characteristics of the barrier.
• Any changes that may adversely influence the crashworthincss 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 th at 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.
• Users will be expected to ensure that the materials in the constructed barrier have essentially the same chemistry, mechanical properties, and geometry as that submitted for acceptance, and that the design will meet the crashworthiness requirements of the FHWA and the NCHRP Report 350.
• To prevent misunderstanding by others, th is letter of acceptance, designated as number B-145 shall not be reproduced except in full. This letter, and the test documentat ion upon which this letter is based, is 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 device for which the applicant is not the patent holder. The acceptance letter is limited to the crashworthiness characteristics of the candidate device, 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.

Enclosures