1200 New Jersey Ave., SE

Washington, D.C. 20590

April 7, 2011

FHWA: HSST:NArtimovich:ms:x61331:4/4/11

File: h://directory folder/HSST/CC-95B Compressor Transition.docx

cc: HSST Nick Artimovich 

0 

In Reply Refer To:

HSST/CC-95B

Mr. Geoff Maus 

Chief Design Engineer

TrafFix Devices, Inc.

160 Avenida La Pata

San Clemente, CA 92673

Dear Mr. Maus:

This letter is in response to your request for the Federal Highway Administration (FHWA) 

acceptance of a roadside safety system for use on the National Highway System (NHS).

Name of system: Compressor Transition

Type of system: Transition from Attenuator to barrier or hazard

Test Level: National Cooperative Highway Research Program (NCHRP) Report 

Test Level 3

Testing conducted by: N/A

Date of request: August 31, 2010

Date initially 

acknowledged:

August 31, 2010

You requested that we find this system acceptable for use on the NHS under the provisions of the 

NCHRP Report 350. 

Requirements 

Roadside safety devices should meet the guidelines contained in the Report 350. The FHWA 

memorandum, “ACTION: Identifying Acceptable Highway Safety Features” of July 24, 1997, 

provides further guidance on crash testing requirements of longitudinal barriers.

Decision

The following device was found acceptable, with details provided below:

• Transition from Compressor Crash Cushion to wide object
2

Description

The enclosed drawings show the Diverging Compressor Transition. This stiffened thrie-beam 

rail has a maximum flare of ten (10) degrees with respect to the sides of the compressor. It is 

designed to maintain the same relatively stiff structure of the end of the compressor for the 

distance needed to connect to a rigid object that is wider than the attenuator.

Crash Testing

No additional crash testing was conducted on this transition as it uses a structure similar to the 

side of the compressor attenuator.

Findings

We concur that the Diverging Compressor Transition may be used at a ten degree flare rate to 

connect to fixed objects that are wider than the rear of the compressor attenuator.

Therefore, the system described in the requests above and detailed in the enclosed drawings is 

acceptable for use on the NHS under the range of conditions the compressor attenuator was

tested, when such use is acceptable to a highway agency.

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

• This acceptance is limited to the crashworthiness characteristics of the systems and does 

not cover their structural features, nor conformity with the Manual on Uniform Traffic 

Control Devices. 

• Any changes that may adversely influence the crashworthiness of the system 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 system being marketed is 

significantly different from the version that was crash tested, we reserve the right to 

modify or revoke our 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 it will meet the crashworthiness requirements of the FHWA and 

NCHRP Report 350.

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

CC-95B and shall not be reproduced except in full. This letter and the test documentation 

upon which it is based are public information. All such letters and documentation may be 

reviewed at our office upon request.

• The compressor is a patented product and considered proprietary. If proprietary devices 

are specified by a highway agency for use on Federal-aid projects, except exempt, nonNHS projects, (a) they must be supplied through competitive bidding with equally 

suitable unpatented items; (b) the highway agency must certify that they are essential for 

synchronization with the existing highway facilities or that no equally suitable alternative 
3

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.

• This acceptance letter shall not be construed as authorization or consent by the FHWA to 

use, manufacture, or sell any patented system for which the applicant is not the patent 

holder. The acceptance letter is limited to the crashworthiness characteristics of the 

candidate system, and the FHWA is neither prepared nor required to become involved in 

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

Sincerely yours,

Michael S. Griffith,

Director, Office of Safety Technologies

Office of Safety 

Enclosure 
COMPRESSOR SYSTEM

19 3/8"

COMPRESSOR TRANSITION

492.76

10°

MAXIMUM ANGLE OF

 TRANSITION PANEL

2

1

40 1/2"

1027.94

20 11/16"

525.46

1"-8X5-5/8" EXPANSION ANCHOR BOLTS WITH 1" WASHERS

TRAFFIC

TRAFFIC

BI-DIRECTIONAL

TRAFFIC

ITEM NO. DESCRIPTION

1 COMPRESSOR SYSTEM

2 COMPRESSOR TRANSITION

D

C

B

A A

B

C

D

8 7 6 5 4 3 2 1

8 7 6 5 4 3 2 1

APPROVED BY:

TITLE:

SIZE

B

DWG. NO. REV

A

COMPRESSOR

DIVERGING TRANSITION

LAYOUT

SHEET 1 OF 1

CHECKED BY: 674 DRAWN BY: DATE:DATE:

DATE:

UNLESS OTHERWISE SPECIFIED:

ALL DIMENSIONS ARE IN INCHES[mm].

TOLERANCES:

FRACTIONAL: X/X 1/16" [1.6mm]

DECIMAL: .000 .0625

DEGREES: 0.5

JEREMY SMITH 08-26-10

FA 08-26-10

FA 08-26-10
1

2

3

4

5

6

7

8

TRANSITION PANEL PANEL

FRAME BRACE

ITEM NO. DESCRIPTION QTY.

1 PANEL 2

2 TRANSITION PANEL 2

3 FRAME BRACE 1

4 1"-8X5-5/8" EXPANSION 

ANCHOR BOLTS 10

5 1" WASHERS 10

6 3/4"-10X8-3/4" ANCHOR 

BOLT 7

7 3/4" WASHERS 7

8 3/4"-10 NUTS 7

D

C

B

A A

B

C

D

8 7 6 5 4 3 2 1

8 7 6 5 4 3 2 1

APPROVED BY:

TITLE:

SIZE

B

DWG. NO. REV

A

COMPRESSOR

DIVERGING TRANSITION

COMPONENTS

SHEET 1 OF 1

CHECKED BY: 673 DRAWN BY: DATE:DATE:

DATE:

UNLESS OTHERWISE SPECIFIED:

ALL DIMENSIONS ARE IN INCHES[mm].

TOLERANCES:

FRACTIONAL: X/X 1/16" [1.6mm]

DECIMAL: .000 .0625

DEGREES: 0.5

JEREMY SMITH 08-26-10

FA 08-26-10

FA 08-26-10