Federal Highway Administration
400 Seventh St., S.W.
Washington, D.C. 20590
May 19, 2006
In Reply Refer To: HSA-10/B-149
Chuck Plaxico, Ph.D.
Battelle Memorial Institute
505 King Avenue
Columbus, Ohio 43201-2693
Dear Dr. Plaxico:
In Mr. Michael Halladay's January 8, 2002, letter to the Ohio Department of Transportation's Mr. Larry Sutherland, the Federal Highway Administration (FHWA) agreed that the Ohio Department of Transportation 32-inch high precast New Jersey shape concrete barrier with a standard pin and loop connection met the evaluation criteria for an National Cooperative Highway Research Program (NCHRP) Report 350 test level 3 (TL-3) temporary traffic barrier. In your May 1, 2006, letter to Mr. Richard Powers of my staff, you requested the FHWA's concurrence that a new barrier, a 50-inch high precast safety shape with a unique pin and loop connection, also be accepted as a TL-3 design.
Prior to conducting a full-scale crash test, Battelle developed a new design for the pin and loop connection through a series of finite element analyses that predicted the design would meet all Report 350 evaluation criteria for a TL-3 temporary barrier. The Ohio Department of Transportation's tall barrier is a 50-inch high, modified New Jersey shape concrete barrier with each segment being 12-feet long. Since the base width remained a standard 24 inches and the top width remained 6 inches, the extended upper sloped face was about 3 degrees steeper than the upper slope of a 32-inch tall New Jersey shape. Reinforcement consisted of five #5 steel bars and two sections of 6 x 6 x W2.9 welded wire fabric. Segments were connected by 1.25-inch diameter x 43-inch long galvanized Grade 5 (high strength) steel bolts passing through 8 loops (4 loops at the ends of each segment). These loops are made from 0.75-inch diameter A36 steel bars bent to an inside radius of 2.25 inches. There are two loops at the top of each segment at one end and a single upper loop at the opposite end. The bottom loops are reversed, with a single loop beneath the upper double loops and vice versa. Each segment also has a single loop, approximately centered between the upper and lower sets of loops. This design, shown as Enclosure 1, was successfully tested at the Transportation Research Center in East Liberty, Ohio on April 12, 2006. Total installation length was about 200 feet and the impact point was approximately 80 feet from the upstream end, resulting in a dynamic deflection of 1.9 meters. Equally severe impacts closer to either unanchored end would be expected to result in greater deflections. Enclosure 2 is the test summary sheet. Vehicular pitch and roll were significantly less than typically noted in concrete barrier tests, probably due to the increase in height and the steeper upper slope that minimizes vehicular climb and roll upon contact.
Based on the crash test results, I agree that this 50-inch high New Jersey portable concrete barrier may be considered an NCHRP Report 350 TL-3 design and used on the National Highway System at the State's discretion. The same barrier design in a 20-foot length may also be considered a TL-3 barrier, provided the longitudinal reinforcement is equivalent to that contained in any other 20-ft segment that has been crash tested successfully. California, New York, and Virginia each have such designs. Please note also that the Oregon Department of Transportation successfully tested a 42-inch tall F-shape concrete barrier with a similar double-shear pin connection to NCHRP Report 350 TL-4. It is very likely that the Ohio Department of Transportation 50-inch tall barrier would have similar capacity.
/original signed by/
John R. Baxter, P.E.
Director, Office of Safety Design
Office of Safety
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