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FHWA Home / Safety / Roadway Departure / Safety Eligibility Letter

Safety Eligibility Letter B-69D

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U.S. Department of Transportation
Federal Highway Administration

1200 New Jersey Ave. S.E.
Washington, D.C. 20590

August 18, 2011

In Reply Refer To: HSST/B-69D

Mr. Gerrit A. Dyke, P.E.
Vice President of Engineering and R & D
Barrier Systems, Inc.
3333 Vaca Valley Parkway, Suite 800
Vacaville, CA 95688

Dear Mr. Dyke:

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: Quickchange Concrete Reactive Tension Barrier System (QMB-CRTS)
Type of system: Moveable Concrete Longitudinal Barrier
Test Level: NCHRP Report 350 Test Level 4 (TL-4)
Testing conducted by: Safe Technologies, Inc. and MIRA, LTD
Date of request: December 28, 2010
Date request acknowledged: January 7, 2011
Task Force 13 designator: SGM22b

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 “Recommended Procedures for the Safety Performance Evaluation of Highway Features” at TL-4.

Requirements
Roadside safety devices should meet the guidelines contained in NCHRP Report 350 if tested prior to December 31, 2010. Devices tested after that date must follow the guidelines contained in the American Association of State Highway and Transportation Official’s (AASHTO) Manual for Assessing Safety Hardware (MASH). The FHWA memorandum “ACTION: Identifying Acceptable Highway Safety Features” of July 24, 1997, provides further guidance on crash testing requirements of roadside features, including crash cushions.

Decision
The following system design was found acceptable, with details provided below:

Description
The system is a portable and moveable reinforced concrete longitudinal barrier intended for use as a temporary barrier in highway construction zones or as a semi-permanent installation for use in reversible-lane operations. It was originally tested and accepted as an NCHRP Report 350 TL-3 barrier and fully described in FHWA Acceptance Letters B69 and B-69A. Only the internal reinforcement was changed to achieve the higher performance level. Barrier segment shape and connection details were unchanged from the TL-3 design.

Crash Testing
Crash testing was performed at Safe Technologies, Inc. in California and at the MIRA. LTD facility in the United Kingdom. Although all of the tests described below were based on the European EN 1317 standards, tests with the NCHRP Report 350 820C and 2000P test vehicles were successfully conducted in conjunction with the FHWA’s original TL-3 acceptance letters for the original QMB-RTS designs. Tests 3-10 and 3-11 are identical to tests 4-10 and 4-11. The results of these earlier tests were included with acceptance letter B-69.

The first test reported here was EN 1317 Test TB11 which is comparable to NCHRP Report 350 Tests 3-10 and 4-10. The test installation consisted of 41 meters (134 feet) of anchored Steel Reactive Tension QMB units for additional mass, followed by 42 meters (138 feet) of 1-meter (39-inch) long CRTS units. Dynamic deflection was 540 millimeters (21.3 inches). Enclosure 2 is the test summary sheet prepared by Safe Technologies, Inc.

The second test completed by Safe Technologies, Inc. was EN 1317 Test TB32. This test installation consisted of 24 meters (79 feet) of unanchored Steel Reactive Tension QMB units for additional mass, followed by 48 meters (157 feet) of 1-meter (39 inch) long CRTS units in the impact area. Another 23 meters (75.5 feet) of Steel Reactive Tension units were connected to the downstream end of the CRTS units. Dynamic deflection was 700 millimeters (27.6 inches). Enclosure 3 is the test summary sheet. The Impact Severity (IS) for this test was recorded as 87.7 kJ, significantly less than the Report 350 recommended value of 138.1 kJ. However, as noted above, test 3-11 was successfully run on the original CRST design and was the basis for FHWA acceptance letter B-69. For that test, the reported dynamic deflection was 610 millimeters (24.0 inches). Since test 3-11 is identical to test 4-11 and the only design change to the CRST was the addition of internal reinforcing, the earlier 3-11 test will suffice to demonstrate the crashworthiness of the CRST with the 2000P test vehicle.

EN 1317 test TB51 was conducted by MIRA, LTD. The test vehicle was a13000-kg (28,660-pound) bus impacting the CRST barrier at a nominal speed of 70 km/hr (43.5 mph) and an impact angle of 20 degrees. The test installation consisted of 99 meters (325 feet) of freestanding CRST units, anchored at both ends. The dynamic deflection was 1.7 meters (5.6 feet). Enclosure 4 is the test summary sheet. Because the impact severity of this test far exceeded the Report 350 target value and the center of mass of the bus was higher than the Report 350 8000S single-unit truck, the FHWA will accept this test as a substitute for Report 350 test 4-12.

Findings
Based upon the successful completion of the EN 1317 tests you provided, we agree that your QMB-CRTS, with additional internal reinforcement, is acceptable for use as a TL-4 longitudinal 3 barrier under NCHRP Report 350 test and evaluation conditions. The design, as described above, may be used on the NHS when such use is acceptable to the contracting authority.

In supplemental correspondence, you stated that all of your CRST barrier segments have been manufactured with the additional reinforcing since successful completion of Test TB32 and that barriers made subsequent to this acceptance letter will be marked to identify their TL-4 capacity. For barriers already in circulation, you can verify TL-3 or TL-4 capacity by determining their date of manufacture if requested to do so by a using agency.

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

 

Sincerely yours,

/* Signature of Michael S. Griffith */

Michael S. Griffith
Director, Office of Safety Design
Office of Safety

Enclosures

Page last modified on June 24, 2011.
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