August 28, 2003 

 

Refer to: HSA-10/B-119B 

Mr. Rodney A. Boyd 

Trinity Highway Safety Products Division 

P.O. Box 568887 

Dallas, Texas 75356-8887 

Dear Mr. Boyd: 

In his August 15, letter to Mr. Richard Powers of my staff, your representative, Mr. Don 

Johnson, requested formal Federal Highway Administration acceptance of a third 

variation to your high-tension, wire rope traffic barrier called the Cable Safety System 

(CASS). Included with the letter were copies of a Texas Transportation Institute (TTI) 

report dated June 2003, entitled “National Highway Cooperative Research Program 

(NCHRP) Report 350 Test 3-11 of the TRINITY CASS System with 2 m Post Spacing 

with Concrete Footings and Sockets” and videotapes of the crash test. Previous 

acceptances were for the CASS System with 3-m and 5-m post spacings, respectively. 

As with the previous two designs, the CASS barrier described in the test report consisted 

of three 19-mm diameter, pre-stretched 3 x 7 strand steel cables mounted 530 mm, 640 

mm, and 750 mm above the ground. Each cable was tensioned to 24kN using 

turnbuckles attached to swaged threaded fittings on each end. These cables were 

supported by 1200-mm long, galvanized 100 x 50 x 4 mm C-channels inserted into 

socketed concrete foundations. The TS 125 mm x 75 mm x 3.2 mm sockets, 380-mm 

long, were cast inside 250-mm diameter concrete cylinders set 600 mm into augured 

holes. The upper central section of each post web was removed to accept the cables, 

which are kept separated in a vertical plane by the insertion of plastic spacer blocks, a 

stainless steel strap, and a plastic cap over the top of each post. 

In test 3-11, the pickup truck impacted near the third-point of the 100 m test installation 

at 100.6 km/h at 25.6 degrees. The reported roll angle was 39.9 degrees, but all occupant 

risk values were well below Report 350 preferred limits. The cable rail deflected 2.06 

meters in the test. Although the tested design met all Report 350 evaluation criteria, you 

requested acceptance of a stronger concrete foundation/steel socket to reduce repair costs 

after impacts. Specifically, you proposed increasing the concrete foundation diameter to 

300 mm and its depth to 760 mm, and you increased the thickness of the steel sleeve from 

the tested 3.2 mm to 4.8 mm. These modifications are acceptable. 
Although the posts in the test installation were set in steel sockets cast into concrete 

cylinders, you requested the use of posts set in driven steel tubes or posts driven directly 

into a strong soil as alternative designs. As long as the post failure mechanism remains 

essentially unchanged (i.e., post failure by bending at the ground line with minimal 

deflection below ground as in the test installation), these options are acceptable for any of 

the tested CASS post spacings. The CASS barrier should be introduced and ended with a 

crashworthy terminal such as the previously accepted TTI breakaway terminal for a hightensioned cable barrier. If the TTI terminal is used, the first six posts beyond the third 

breakaway anchor post must be the same posts at the same spacing as were used in the 

terminal certification tests unless you repeat the appropriate tests using the CASS post at 

these locations. A non-crashworthy terminal may be used if both the upstream and 

downstream anchors are adequately shielded. 

In summary, the CASS barrier, with posts set on 2-m centers, meets NCHRP Report 350 

evaluation criteria as a test level 3 barrier and may be used on the National Highway 

System (NHS) as either a roadside or median barrier when such use is acceptable to the 

contracting agency. Since it is a proprietary product, the provisions of Title 23, Code of 

Federal Regulations, Section 635.411 apply to its use on Federally funded projects, 

except exempt non-NHS projects. 

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

• This acceptance is limited to the crashworthiness characteristics of the CASS 

system and does not cover its long-term durability or maintenance requirements. 

• Any design changes that may adversely influence the crashworthiness of the 

device may require a new acceptance letter.

• Should the FHWA discover that the qualification testing was flawed, that inservice 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 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, and that they will meet the crashworthiness 

requirements of FHWA and NCHRP Report 350. 

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

number 

B-119B, 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. 

Sincerely yours, 

 

 (original signed by Harry W. Taylor) 
 for: John R. Baxter, P.E. 

 Director, Office of Safety Design 

 Office of Safety