400 Seventh St., S.W. 

Washington, D.C. 20590

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 

 
2

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: 

• Our acceptance is limited to the crashworthiness characteristics of the PARAGLAS 

SOUNDSTOP TL-4 System and is not intended to address its structural features. 

• Any changes that may adversely influence the crashworthiness 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 that was crash tested, it reserves the right to 

modify or revoke its acceptance. 

• You will be expected to supply potential users with detailed drawings and 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. 

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

B-136 shall not be reproduced except in full. This letter, and the test documentation upon 

which this letter is based, is public information. All such letters and documentation may 

be reviewed at our office upon request. 

• The PARAGLAS SOUNDSTOP TL-4 System is considered to be proprietary. If 

proprietary devices are specified by a highway agency for use on Federal-aid projects, 

except exempt, non-NHS projects, they: (a) must be supplied through competitive 

bidding with equally suitable unpatented items; (b) the highway agency must certify that 

they are essential for synchronization with existing highway facilities or that no equally 

suitable alternative exists or; (c) they must be used for research or for a distinctive type of 

construction on relatively short sections of road for experimental purposes. Our 

regulations concerning proprietary products are contained in Title 23, Code of Federal 

Regulations, Section 635.411, a copy of which is enclosed (Enclosure 3) for your ready 

reference. 

Sincerely yours, 

 

/original signed by/ 

John R. Baxter, P.E. 

 Director, Office of Safety Design 

 Office of Safety 

3 Enclosures 


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