U.S. Department of Transportation
Federal Highway Administration
1200 New Jersey Avenue, SE
Washington, DC 20590
202-366-4000


Skip to content
FacebookYouTubeTwitterFlickrLinkedIn

Safety

eSubscribe
eSubscribe Envelope

FHWA Home / Safety / Roadway Departure / Safety Eligibility Letter

Safety Eligibility Letter CC-117

Download Version
PDF [1,737 KB]

DOT logo
U.S. Department of Transportation
Federal Highway Administration

1200 New Jersey Ave. S.E.
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:

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.

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:

 

Sincerely yours,

/* Signature of Michael S. Griffith */
Michael S. Griffith
Director, Office of Safety Technologies
Office of Safety
Page last modified on January 17, 2013.
Safe Roads for a Safer Future - Investment in roadway safety saves lives
Federal Highway Administration | 1200 New Jersey Avenue, SE | Washington, DC 20590 | 202-366-4000