U.S. Department of Transportation
Federal Highway Administration
1200 New Jersey Avenue, SE
Washington, DC 20590
202-366-4000
 U.S. Department of Transportation Federal Highway Administration |
Memorandum |
| Subject: | ACTION: NYS Concrete Barrier with Box Beam Stiffener FHWA Eligibility Letter B-239 |
Date: November 1, 2012 |
| From: | Michael S. Griffith Director, Office of Safety Technologies Office of Safety |
In Reply Refer To: HSST |
| To: | Jonathan D. McDade Division Administrator Albany, New York |
This memorandum is in response to your request for the Federal Highway Administration (FHWA) to review a roadside safety system for eligibility for reimbursement under the Federal-aid highway program
| Name of system: | New York State Temporary Concrete Barrier with Box Beam Stiffener |
|---|---|
| Type of system: | Portable Concrete Barrier with reduced deflection |
| Test Level: | MASH Test Level 3 |
| Testing conducted by: | Mid West Roadside Safety Facility (MWRSF) |
Decision:
The following device is eligible, with details provided below and in the attachments:
Based on a review of crash test results certifying the device described herein meets the crash test and evaluation criteria of the National Cooperative Highway Research Program (NCHRP) Report 350, the device is eligible for reimbursement under the Federal-aid highway program. Eligibility for reimbursement under the Federal-aid highway program does not establish approval or endorsement by the FHWA for any particular purpose or use.
The FHWA, the Department of Transportation, and the United States Government do not endorse products or services and the issuance of a reimbursement eligibility letter is not an endorsement of any product or service.
Requirements
To be found eligible for Federal-aid funding, roadside safety devices should meet the crash test and evaluation criteria contained in the National Cooperative Highway Research Program (NCHRP) Report 350 or the American Association of State Highway and Transportation Officials' Manual for Assessing Safety Hardware (MASH).
Description
Previous crash testing of the New York State Department of Transportation (NYSDOT) temporary concrete barrier (TCB) system had been conducted according to the National Cooperative Highway Research Program (NCHRP) Report 350 criteria, and documented in FHWA Letter B-94, dated January 24, 2002. In the 2001 test at the Texas Transportation Institute, the unpinned NYSDOT TCB system, a 2,076-kg (4,577-lb) pickup truck impacted the ten barrier system at a speed of 100.8 km/h (62.6 mph) and at an angle of 25.6 degrees. During the impact, the vehicle was redirected smoothly and the barrier system experienced 1,270 mm (50 in.) of deflection. The upstream end was pulled 148 mm (5.8 in.) longitudinally downstream, while the downstream end was displaced 5 mm (0.2 in.) longitudinally upstream, or toward the impact point.
Crash Testing of Stiffened Barrier
In the 2008 testing at the Midwest Roadside Safety Facility (MRSF) the 60.96-m (200-ft) long test installation consisted of box beam stiffened temporary concrete barrier sections in a free-standing configuration with both end sections anchored. The ten 6,096-mm (20-ft) long, temporary concrete barrier sections were installed with the first and last sections attached to the concrete using nine 25-mm (1-in.) diameter by 394-mm (15.5-in.) long, A36 steel rods, five anchors and four anchors on the traffic and back sides, respectively. Each anchor rod was driven into a hole drilled in the concrete to an embedment depth of 127 mm (5 in.).
The three joints between barrier nos. 4 and 7 were stiffened with a box beam section consisting of a 152-mm x 152-mm x 4.8-mm (6-in. x 6-in. x 0.1875-in.) ASTM A500 Grade C box beam, which was 3,658 mm (12 ft) long. The box beams were connected to the barriers with 19-mm (0.75-in.) diameter by 432-mm (17-in.) long, Grade 5 continuously threaded rods and nuts. An 83-mm (3.25-in.) outside diameter x 22-mm (0.875-in.) inside diameter x 9.5-mm (0.375-in.) thick Grade 5 fender washer was placed on the traffic side of the barrier between the barrier and the nut. A 203-mm x 203-mm x 6.4-mm (8-in. x 8-in. x 0.25-in.) A36 steel plate was placed on the back side of the barrier between the nut and the box beam section.
Details of the crash are in the attached Figure 29 Summary of Test Results. The maximum dynamic deflection was 700 mm (approximately 28 inches). This is 44 percent less deflection than the 1,270 mm (50 in.) recorded in the test of the un-stiffened barrier.
The analysis of the test results for test no. NYTCB-1 showed that the stiffened temporary concrete barrier system with anchored ends adequately contained and redirected the 2270P vehicle with controlled lateral displacements of the barrier system. This test was determined to meet the TL-3 safety performance criteria of test designation no. 3-11 found in MASH.
Summary and Standard Provisions
Therefore, the system described and detailed in this memorandum is eligible for reimbursement and may be installed under the range of conditions tested. We also concur that the same stiffening method may be used to reduce the deflection of other portable concrete barrier systems with the following provisions:
1) The length of the individual barrier segments are at least 20 feet long.
2) The deflection of the system to be retrofit was no greater than 50 inches under NCHRP Report 350 Test Level 3 conditions.
3) The barriers are anchored at both ends to achieve the limited deflection properties demonstrated in the crash testing. If the end sections are not anchored then the barrier line, with stiffeners, should be extended until the barrier’s desired deflection can be achieved.
Please note the following standard provisions that apply to FHWA eligibility letters:
Attachments
Sincerely yours, /* Signature of Michael S. Griffith */ Michael S. Griffith |
Enclosures
