In Reply Refer To: HSA-10/B-141A

400 Seventh St., S.W. 

May 2, 2006 Washington, D.C. 20590

 Mr. Stephen L. Brown 

 President 

 Trinity Highway Safety Products, Inc. 

 P.O. Box 568887 

 Dallas, Texas 75356-8887 

Dear Mr. Brown: 

In my November 17, 2005, acceptance letter B-141, I agreed that a 3-rope CASS cable barrier 

using weakened S4 x 7.7 structural steel posts set in concrete footings on 20-foot centers met 

the National Cooperative Highway Research Program (NCHRP) Report 350 evaluation criteria 

as a test level 3 (TL-3) traffic barrier. While I also agreed that the same system with directdriven posts would likely meet Report 350 criteria, I stated that testing would need to be done 

to determine the design deflections for alternative post designs. The Texas Transportation 

Institute conducted a test on the system described below on February 6, 2006, and detailed the 

results in its April 2006 report, “NCHRP Report 350 Test 3-11 of the CASS-TL3 with Driven 

Posts Spaced at 20 Ft.” 

In his April 21, 2006, letter, Mr. Brian Smith sent copies of this report to Mr. Richard Powers 

and requested the Federal Highway Administration’s (FHWA) acceptance of the TL-3 

modified CASS design which used 6-foot long, direct driven S4 x 7.7 steel posts on 20-foot 

centers. The 3/4-inch diameter cables were set at the same heights as in the earlier test 

(i.e., 21.0, 25.2, and 29.5 inches above the ground surface, measured to the center of each 

cable). The posts were again weakened by adding two 11/16-inch diameter holes through each 

flange at ground line as shown in the enclosure to this letter, and were driven to a depth of 

approximately 39 inches. The cables were not pre-stretched, but were tensioned to 

5,600 pounds force for the test. The dynamic deflection for the 334-foot long test installation 

was 6.2 feet. By comparison, the deflection for the socketed posts in your earlier test was 

7.7 feet. 

The CASS TL-3 design described above may be used as either a roadside or median barrier on 

the National Highway System (NHS) when such use is acceptable to the contracting agency. 

Although the cables used in the test were not pre-stretched, this acceptance is also valid if and 

when pre-stretched cables are used, assuming that the recommended post-tensioning is applied 

to the barrier. 

 
2

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

• Our acceptance is limited to the crashworthiness characteristics of the CASS TL-3 design 

and does not cover its structural features, durability, or maintenance characteristics. 

• Any additional design or material changes that may adversely affect the crashworthiness 

of the barrier 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 barrier 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. 

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

B-141A, 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 CASS Cable Barrier includes patented components and is considered proprietary. 

When 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. 

 Sincerely yours, 

 /original signed by/ 

 

 John R. Baxter, P.E. 

 Director, Office of Safety Design 

 Office of Safety 

Enclosure 
DETAIL A

1

1

2

2

A A

B B

A

BILL OF MATERIAL

QTY PC NO. ITEM DESCRIPTION LENGTH Lbs / Each MATERIAL

1 1 S 4 x 7.7 6'-0" 45.36 A36

REV

CHK:

DRW:

SHIPPING WT:

GALV SPEC:

PROJ.

TRINITY INDUSTRIES, INC.

HIGHWAY SAFETY DIVISION

DWG NO:

033956 2

48.1 lb

A123

CASS-TL3

E.A.S

CASS-TL3 - LONG POST

S4 x 7.7 x 6'-0"

(DRIVEN) 1/5/2006

B.S. 1/5/2006

100% Melted and Manufactured in the USA

n11/16" (4)

HOLES THRU

IN LINE.

15/16"

2"

(4")

11 13/16"

5/8" 4

5/16" 4

5/16"

2

2

5/3

2" 4

5/16" 4

5/16"

R13/32"

13/16"

1 3/8"

13/16"

1 3/8"

13/16"

2'-8 1 4/ " 1 1/2"

1

6'-0" - 3/16" 1/8" +

S

4

x

7.7

x

3/4"

n11/16" (2)

GALV. HOLES

N.S. ONLY!

(OPTIONAL)

2"