September 12, 2003

HSA-10/B-117

Ronald K. Faller, Ph.D., P.E.
Research Assistant Professor
University of Nebraska - Lincoln
1901 Y Street, Bldg. C
Lincoln, NE 68588-0601

Dear Mr. Faller:

In your August 25 letter to Mr. A. George Ostensen, you requested the Federal Highway Administration's (FHWA) formal acceptance of three non-proprietary longitudinal barrier systems for use on the National Highway System (NHS). The first system will be addressed in this letter, and the remaining two designs will be covered in subsequent correspondence. The first design consisted of stacked steel H-Sections connected end-to-end and bolted to a simulated bridge deck. It was developed specifically for use at locations where typical lateral deflections for temporary concrete barrier were unacceptable.

The tested design was a modification of a temporary barrier developed and used by the Iowa Department of Transportation. The original design consisted of two ASTM A36 steel HP 356 mm x 109 mm x 6.1-m long beams, stacked one above the other with the box section formed by the stacked HP shapes filled with concrete. The stacked barrier is approximately 29 inches (741 mm) high and its width is approximately 13.5 inches (346 mm). The tested design used four steel angle brackets welded to the traffic side of the barrier through which the barrier was fastened to the simulated bridge deck with four 19-mm diameter x 57-mm long ASTM A307 bolts placed into drop-in concrete anchors. Four angle brackets may also be attached to the field side of the barrier so it can be installed along the opposite side of the bridge without having to be rotated 180 degrees, but only the traffic side of the barrier is bolted to the bridge deck. Whereas the original design used welded splice plates to connect the upper and lower HP sections and to join adjacent segments, the final design used a continuous weld to connect the upper and lower beams and shear plates with drop pins to connect adjacent segments of barrier. Specific dimensions and other design details are shown in Enclosure 1.

The National Cooperative Highway Research Program (NCHRP) Report 350 test 3-11 was successfully conducted on the final design and is described in the Midwest Roadside Safety Facility's May 30, report entitled, Development of a Steel H-Section Temporary Barrier for use in Limited Deflection Applications." Enclosure 2 is a summary sheet of the test results.

I agree with your conclusion that the H-Section barrier met all NCHRP Report 350 evaluation criteria for a test level 3 barrier and conclude that it can be used as such on the NHS when its use is acceptable to the contracting agency. Although the reported dynamic deflection of the barrier was 314 mm when installed 330 mm from the edge of the simulated deck, you concluded that the barrier could safely be installed within 150 mm from the edge without danger that the barrier would separate or be dislodged from the deck. I concur with this assessment, but suggest that all field installations be monitored to verify acceptable performance under these conditions.

Sincerely yours,

(original signed by John R. Baxter)

John R. Baxter, P.E.
Director, Office of Safety Design
Office of Safety

2 Enclosures