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FHWA Home / Safety / Roadway Departure / Safety Eligibility Letter

Safety Eligibility Letter CC-112

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U.S. Department of Transportation
Federal Highway Administration

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

February 9, 2011

In Reply Refer To: HSST/CC-112

Mr. Barry D. Stephens, P.E.
Sr. Vice President Engineering
Energy Absorption Systems, Inc.
3617 Cincinnati Avenue
Rocklin, CA 95678

Dear Mr. Stephens:

This letter is in response to your request for the Federal Highway Administration (FHWA) acceptance of a roadside safety device for use on the National Highway System (NHS).

Name of device: 6-bay QuadGuard® M10; and,
6-bay QuadGuard® M10 Wide
Type of device: Impact Attenuator and Transitions
Test Level: AASHTO Manual for Assessing Safety Hardware (MASH)
Test Level 3 (TL-3)
Testing conducted by: E-Tech Testing Services, Inc.
Date of request: May 3, 2010
Date of completed package: July 23, 2010
Task Force 13 Designator: SCI26 (M10)
SCI27 (M10Wide)

You requested that we find this device acceptable for use on the NHS under the provisions of the MASH testing standard.

Requirements
Roadside safety devices should meet the guidelines contained in the MASH. 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 devices are acceptable, with details provided below:

Description
The M10 and M10W are redirective, non-gating 6-bay crash cushions. The MASH design has been revised from National Cooperative Highway Research Program (NCHRP) Report 350 design to now include a reinforced lower front bracket, a new upper front bracket and new cartridge types. Features of both M10 and M10W systems are shown in the enclosed drawings for reference.

The M10 and M10W systems have an overall length of 22’-0” [6.71 m]. The M10 can be configured with backup widths of 24 inches [610 mm], 30 inches [762 mm], and 36 inches [914 mm]. The M10W can be configured with back-up widths of 69 inches [753mm] and 90 inches [2285 mm]. The overall height of both M10 and M10W is 32 inches [817 mm]. The system consists of energy absorbing cartridges surrounded by a framework of steel Quad-Beam™ guardrail that can telescope rearward during head-on impacts. The system has a center monorail that will resist lateral movement during side angle impacts and a back up structure that will resist movement during head-on impacts.

Components from the 5-Bay QG II unit that are used on the new 6-Bay QG M10 unit are:

  1. QG foundation–anchored center Monorail
  2. QG Fender Panels
  3. QG Diaphragms
  4. QG Backup
  5. MP-3™ Concrete Anchors
  6. 14ga steel wrap-around sheet metal Nose
  7. 50mm [2 inches] Lower Nose Cartridge Bracket
  8. 10ga steel rail guide Shims

Components that were enhanced to achieve the required performance include:

  1. QG Type M-I cartridges (4 required)
  2. QG Type M-II cartridges (3 required)
  3. A hold down bracket was added to the nose cartridge to contain the cartridge and maximize its energy absorption.
  4. The bottom nose cartridge bracket attached to the diaphragm was reinforced to help restrain the cartridge to maximize its energy absorption.
  5. Transition Hardware — steel posts (only) in strong soil

System drawings are also included within this correspondence for review and reference.

Crash Testing
Full-scale crash tests were conducted into the new QG M10 as required per MASH under the TL-3 guidelines. For the M10 system, MASH Tests 3-31 was conducted on the 24-inch [610 mm] system and MASH Test 3-23 was conducted on the 36-inch [914 mm] system. The test results are as follows and can also be reviewed in enclosed MASH Test Matrix:

Test 3-31:
Impact speed = 99.0 km/h
Ridedown = −17.6 g’s
Longitudinal ΔV = 8.4 m/s.

Test 3-32:
Impact speed = 97.0 km/h
Ridedown = −17.8 g’s
Longitudinal ΔV = 11.1 m/s.

Due to a higher energy of the MASH test vehicles, test 3-34 and test 3-36 were conducted on the 24-inch [610 mm] system in addition to the newly specified test 3-37. The results of these tests are as follows:

Test 3-34:
Impact speed = 102.5 km/h,
Longitudinal ridedown = −10.6 g’s,
Longitudinal ΔV = 8.9 m/s,
OCD: AS1020000

Test 3-36:
Impact speed = 99.0 km/h,
Lateral ridedown = 14.2 g’s,
Lateral ΔV = 7.4 m/s,
OCD: AS1110000

Test 3-37:
Impact speed = 99.7 km/h,
Longitudinal ridedown = 7.8 g’s,
Longitudinal ΔV = −7.8m/s,
OCD: LF0030000

For the M10W system, a comparison was made using existing NCHRP Report 350 crash test results for the 5-bay QG II (flared) and original QG (parallel) systems. Since the results of these tests indicated that test 3-31 and 3-32 are similar for parallel and flared systems, equivalence to the NCHRP Report 350 device in lieu of furthered testing of the M10W systems, with backup widths of 69-inch [753mm] and 90-inch, is requested.

A discussion regarding the M10 and M10W transition systems was conducted with FHWA Office of Safety on March 8, 2010. It was agreed the M10 to W-beam transition represents a worst case condition for pocketing and snagging of the test vehicle. In addition and in this particular case, the MASH test 3-21 is considered equivalent to test 3-37. In addition, a successful test 3-37 would serve to represent all of the following submitted transitions with caveat that required spacing and specification of steel posts for w-beam transition must also be same for M10 transition to thrie-beam to provide similar system strength:

  1. Transition QG M10 to W-beam
  2. Transition QG M10 to thrie-Beam
  3. QG 4” offset Transition to CMB
  4. QG 9” offset Transition to CMB (No wide system version)
  5. Transition QG to vertical wall
  6. QG 6” offset transition to single slope barrier

In addition, a waiver is requested of test 3-38 (1500A crash test) as per MASH Section G computations (using existing tests 3-31 result).

Findings
The M10 and M10W systems meet evaluation criteria as per MASH for a redirective, non-gating crash cushion at TL-3 impact conditions. Therefore, these systems are acceptable for use on the NHS when such use is acceptable to the contracting authority. In addition, the M10 can be installed with aforementioned transition hardware with caveat that steel posts with a specified spacing are used for W-beam and thrie-beam transitions as described in test 3-37 report. 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 Techologies
Office of Safety

Enclosures

Page last modified on January 17, 2013.
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