May 15, 2003 

Refer to: HSA-10/B-119A 

Mr. Rodney A. Boyd 

Trinity Highway Safety Products Division 

P.O. Box 568887 

Dallas, Texas 75356-8887 

Dear Mr. Boyd: 

In his March 31 letter to Mr. Richard Powers of my staff, your representative, Mr. Don Johnson, 

requested formal Federal Highway Administration (FHWA) acceptance of a modified version of 

the wire rope traffic barrier called the Cable Safety System (CASS) that was originally accepted 

for use on the National Highway System (NHS) in my May 13, acceptance letter B119. Whereas 

the original design used a 3-m post spacing, the modified design used a 5-m spacing for all the 

CASS line posts. Included with the second letter were copies of a Texas Transportation Institute 

report dated March 2003, entitled “NCHRP Report 350 test 3-11 of TRINITY Cable Safety 

System (CASS) with 5m Post Spacing” and videotapes of the crash test. 

The CASS barrier remained as described in my original acceptance letter, consisting of three 

19 mm diameter, pre-stretched 3 x 7 strand steel cables. Mounting heights were 530 mm, 

640 mm, and 750 mm above the ground and each cable was tensioned to 24kN using turnbuckles 

attached to swaged threaded fittings on each end. These cables were supported by 1600-mm 

long, galvanized 100 x 50 x 4 mm C-channels driven into a Report 350 standard soil. As shown 

on Enclosure 1, the upper central section of the 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 this modified version, the posts were 

set on 5-m centers rather than 3-m apart as in the initial test. A 2000-kg pickup truck impacted 

the CASS barrier at 99.4 km/h near the mid-point of a 100-meter long test installation at an 

impact angle of 25.7 degrees. As seen on the test summary sheet (Enclosure 2), all Report 350 

evaluation criteria were met. The cable rail deflected 2.8 meters with the 5-m post spacing. 

Thus, the CASS barrier, as described above, meets NCHRP Report 350 evaluation criteria as a 

test level 3 barrier and may be used on the 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. The need to use crashworthy (or shielded) terminals 

emphasized in my May 13 letter for the 3-m post spacing design applies to the 5-m post spacing 

layout as well. 
2

This Acceptance Letter shall not be construed as authorization or consent by the FHWA to use, 

manufacture, or sell any proprietary device for which ownership may be in question. All FHWA 

acceptances are based primarily on staff review of the crashworthiness characteristics of the 

proposed device and we are neither prepared nor required to become involved in issues 

concerning patent law. Patent issues, if any should arise, are to be resolved by the applicant. 

Sincerely yours, 

(original signed by Michael S. Griffith) 

 

Michael S. Griffith 

 Acting Director, Office of Safety Design 

 Office of Safety 

2 Enclosures 
7 

Details of CASS post.

1 i1 f
20 

Summary of results for test 400001-TCR2 (CASS w/5 m spacing), NCHRP Report 350 test 3-

0.000 s 0.193 s 0.483 s 

General Information

Test Agency . . . . . . . . . . . . . Test No. . . . . . . . . . . . . . . . . Date . . . . . . . . . . . . . . . . . . . 

Test Article

Type . . . . . . . . . . . . . . . . . . . Name . . . . . . . . . . . . . . . . . . Installation Length (m) . . . . . Material or Key Elements . . . 

Soil Type and Condition . . . . Test Vehicle

Type . . . . . . . . . . . . . . . . . . . Designation . . . . . . . . . . . . . Model . . . . . . . . . . . . . . . . . . Mass (kg)

Curb . . . . . . . . . . . . . . . . . Test Inertial. . . . . . . . . . . . Dummy. . . . . . . . . . . . . . . Gross Static . . . . . . . . . . . 

Texas Transportation Institute400001-TCR201/31/03GuardrailTrinity Cable Safety System (CASS)101.93 Wire Ropes Supported By C-ChannelMild Steel Support PostsStandard Soil, DryProduction2000P1998 Chevrolet 2500 Pickup20752050 N/A2050

Impact Conditions

Speed (km/h) . . . . . . . . . . . . . . . . Angle (deg) . . . . . . . . . . . . . . . . . 

Exit Conditions

Speed (km/h) . . . . . . . . . . . . . . . . Angle (deg) . . . . . . . . . . . . . . . . . 

Occupant Risk Values

Impact Velocity (m/s)

x-direction . . . . . . . . . . . . . . . . y-direction . . . . . . . . . . . . . . . . 

THIV (km/h) . . . . . . . . . . . . . . . . . Ridedown Accelerations (g's)

x-direction . . . . . . . . . . . . . . . . y-direction . . . . . . . . . . . . . . . . 

PHD (g’s) . . . . . . . . . . . . . . . . . . . ASI . . . . . . . . . . . . . . . . . . . . . . . Max. 0.050-s Average (g's)

x-direction . . . . . . . . . . . . . . . . y-direction . . . . . . . . . . . . . . . . z-direction . . . . . . . . . . . . . . . . 

99.425.777.4 9.5 2.5 3.314.0-4.4 5.2 6.3 0.36-2.3 3.0-1.9

Test Article Deflectio

Dynamic . . . . . . . . Permanent . . . . . . Working Width . . . 

Vehicle Damage

Exterior

VDS . . . . . . . . . CDC . . . . . . . . . 

Maximum Exterior

Vehicle Crush (mm

Interior

OCDI. . . . . . . . . 

Max. Occ. Compart.

Deformation (mm) 

Post-Impact Behavio

(during 1.0 s after imMax. Yaw Angle (deMax. Pitch Angle (deMax. Roll Angle (deg