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May 18, 2005
In Reply Refer To: HSA-10/B-136
Mr. Stephen Barratt
CYRO Industries, Inc.
100 Enterprise Drive, Suite 700
P.O. Box 5055
Rockaway, New Jersey 07853
Dear Mr. Barratt:
In his April 12 letter to Mr. Richard Powers of my staff, Mr. Eric Humphries provided preliminary information on your PARAGLAS SOUNDSTOP Noise Barrier System that was mounted on the back of a 32-inch tall single slope barrier. On May 12, a copy of the Midwest Roadside Safety Facility's April 22 test report entitled “Design and Evaluation of CYRO's PARAGLAS SOUNDSTOP Noise Barrier System” was delivered to this office.
The PARAGLAS SOUNDSTOP® TL-4 system consists of transparent PARAGLAS SOUNDSTOP® GS CC Noise Barrier Sheet panels supported by galvanized ASTM A36 steel W8 x 40 posts mounted to the back vertical face of a 32-inch tall concrete safety shape bridge rail. The patented GS CC Sheet panels are infused with polyamide filaments to contain fragments in the event the panel is hit and damaged during a collision. The tested installation was 19-feet high and its traffic face consisted of three galvanized TS 7 x 4 steel tubes set 38 inches, 60 inches and 128 inches above the ground. The lowest rail is 5/16-inch thick; the upper two are 3/16-inch thick. Enclosure 1 shows these major system components. In the test installation, the traffic faces of the horizontal rail elements were offset from the top of the concrete barrier by approximately 3.25 inches and the traffic faces of the vertical support members were offset approximately 10.25 inches. Two tests were run to ensure that the addition of the sound wall would not adversely affect the TL-4 performance of the 32-inch tall concrete bridge rail. Although some snagging on the support posts occurred both with the single-unit truck and with the pickup truck, the tests were deemed to meet all NCHRP Report 350 evaluation criteria. The sound wall was essentially undamaged in the tests, summaries of which are shown in Enclosure 2.
After reviewing the report and the crash test documentation, I conclude that the addition of your PARAGLAS SOUNDSTOP Noise Barrier System to the vertical backside of a 32-inch tall concrete safety shape bridge rail, including the NJ or F-shape profile as well as the tested single slope design, will not change the test level of the bridge rail. All such bridge railings would retain their TL-4 designation with the addition of the noise wall as described herein. If a 42-inch tall barrier is used, the lowest rail would not be needed, but the remaining two should be retained at their tested heights. Because of the added steel rails, the crash performance of the concrete safety shapes is essentially improved by limiting vehicle climb to some extent and by significantly reducing the roll angle of larger vehicles. If used behind a vertical concrete bridge railing rather than a safety shape, its performance is likely to be further improved over that seen in the crash tests.
Please note the following standard provisions that apply to the FHWA letters of acceptance:
Sincerely yours,
/original signed by/
John R. Baxter, P.E.
Director, Office of Safety Design
Office of Safety
