1200 New Jersey Ave., SE

Washington, D.C. 20590

June 21, 2011

In Reply Refer To:

HSST/CC-117

Felipe Almanza

Technical Engineering Director

TrafFix Devices, Inc.

160 Avenida La Pata

San Clemente, California 92673

Dear Mr. Almanza:

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: SLED – Sentry Longitudinal Energy Dissipater

Type of system: Gating Crash Cushion / Impact Attenuator

Test Level: NCHRP Report 350 Test Level 2

Testing conducted by: KARCO Engineering

Date of request: November 29, 2010

Date initially acknowledged: December 13, 2010

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

National Cooperative Highway Research Program (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:

• TL-2 SLED – Sentry Longitudinal Energy Dissipater
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Description 

The SLED End Treatment CMB is a non-redirective, gating crash cushion, tested as an end 

treatment for use with concrete median barriers (CMBs). For this test, three (3) F-shape concrete 

median barriers were used. The SLED End Treatment CMB system consists of five (5) main 

components: three (3) yellow SLED End Treatment sections, one (1) containment impact sled, 

and one (1) SLED End Treatment Transition. The length of the SLED End Treatment

CMB, excluding the concrete elements, is 5.7 m (18.6 ft). The total tested array length is 15.1 m

(49.5 ft.).

The yellow elements of the SLED End Treatment CMB measure 1.16 m (3.8 ft) tall, 1.93m (6.3 

ft) in length from pin to pin, and weigh 72.5k9 (160 lb). The yellow element of the SLED End 

Treatment CMB is made of high density polyethylene (HDPE) plastic, and has a 200 mm (8 in) 

diameter fill hole. The front yellow element has 6 holes drilled near the base to ensure that the 

element cannot be filled with water. The other two yellow elements are filled with water.

Each SLED End Treatment CMB element contains eleven knuckles per side interlocked together 

with a vertical drop t-pin aligning a series of concentric pin holes. This provides a positive 

connection between the eleven knuckle sections per side. Within the four upper knuckles on 

each SLED End Treatment CMB element are four molded in corrosion resistant steel wire ropes.

Pinned to the front of the yellow end treatment section is the galvanized steel containment 

impact sled. The impact sled consists of a steel tube frame and sheet metal construction. The 

impact sled is approximately 0.77 m (2.54 ft) tall, 0.69 m (2.3 ft) wide, 2.25 m (7.4 ft) long, and 

weighs 95 kg (2001b).

Following the SLED End Treatment CMB are three (3) F-shape concrete median barriers. These 

three (3) elements add an additional length of 12.3 m (40.3 ft). Each F-shape concrete median 

barrier is approximately 1.07 m (42 in) tall, 0.66 m (26 in.) wide at the base,

3.05 m (120 in) long and weighs approximately 2650 kg (5483 lbs). The concrete median 

barriers were anchored to the concrete using a steel plate and drop in anchors. 

The SLED End Treatment CMB connects to the F-Shape concrete median barriers with a steel

SLED End Treatment Transition. The SLED End Treatment Transition is made of three main 

components: the steel transition frame, left transition panel, and right transition panel. The steel 

frame of the transition is positively connected to the last water filled SLED End Treatment with a

pin. The left and right transition panels are connected to the transition frame with pins. Both 

transition panels are anchored to the first concrete median barrier using four (4) anchor bolts.

Crash Testing

A non-redirective gating crash cushion requires the following tests be conducted:

3-40, 3-41, 3-42, 3-43, and 3-44. Tests 3-40, 3-41, 3-43 and 3-44 were conducted on the TL-3 

SLED shielding either a fixed concrete barrier or a water-filled Sentry installation. The 

remaining tests were waived, and the TL-3 SLED was found acceptable in FHWA Acceptance 

Letter CC-114 dated February 9, 2011.
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All physical crash test summaries are included as enclosures to this correspondence.

Findings

Because the SLED is a non-redirecting, gating cash cushion, it should be applied to hazards that 

are not likely to be impacted at an angle on the side at any significant velocity. We note also that 

proper antifreezing agents must be used as filler when the SLED and Sentry products are used in 

areas where low temperatures can be anticipated. All users of this device should be made aware 

of the factors that contribute to its proper performance.

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

use on the NHS under the range of conditions tested, when such use is acceptable to a highway 

agency.

Please note the following standard provisions that apply to 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-114 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 Sentry and SLED are patented products and considered proprietary. If proprietary 

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

exempt, non-NHS 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 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.
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• 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