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                Safety Eligibility Letter B-150B
  
  **Hardware Type:**
            Longitudinal Barriers and Bridge Rails
                          **Code:**
            B-150B
                          **Date:**
            07/16/2008
                          **Testing Criteria:**
            NCHRP 350
                          **Manufacturer:**
            Gregory Highway Products
                          **Device Description:**
            GMS Barrier with 12 ft 6 inch post spacing
                          **View PDF:**
            b150b.pdf (134.36 KB)
    
    Safety Eligibility Letter B-150B


			
			
			 
			**Download Version**PDF [193 KB]
			
			DOT logoU.S. Department of Transportation**Federal Highway Administration**
			1200 New Jersey Ave. S.E.Washington, D.C. 20590
			July 16, 2008
			In Reply Refer To: HSSD/B-150B
			
			Mr. Andrew Artar
Vice President Sales and Marketing
Gregory Highway  Products
4100 13th    Street, SW
Canton, OH  44710
				
			Dear Mr. Artar:
			This letter is in response to your request for Federal  Highway Administration (FHWA) acceptance of a roadside safety system for use on  the National Highway System (NHS).
			Name  of systems:Gregory Mini Spacer  (GMS) Guardrail with 12’6” Post Spacing  GMS  Median Barrier with 12’6” Post SpacingType of  systems:Steel W-Beam BarriersTest Level:The National  Cooperation Highway Research Program (NCHRP)Report 350 Test Level 3 (TL-3)Testing  conducted by:Southwest Research InstituteDate of  request:March 22, 2008Date of  follow up:April 28, 2008You requested that we find these systems acceptable for use  on the NHS under the provisions of the proposed American Association of State Highway and  Transportation Officials’ Manual for Assessing Safety Hardware-2008 (MASH-08).
			**Requirements**Roadside safety systems should meet the  guidelines contained in the NCHRP Report 350, "Recommended Procedures for  the Safety Performance Evaluation of Highway Features". The FHWA Memorandum “ACTION:  Identifying Acceptable Highway Safety Features” of July 25, 1997, provides  further guidance on crash testing requirements of longitudinal barriers. However, in this case you have chosen to  anticipate the adoption of MASH-08, an option that the FHWA has offered with the  understanding that additional testing may need to be done if changes to the  test criteria are made before MASH-08 is formally adopted.
			**Description**The test article was a Modified G4(1S)  longitudinal barrier. The length-of-need  section consisted of standard unmodified 12-ga W-beam mounted directly to  standard unmodified 6 foot long W6 x 8.5 steel posts using the  proprietary GMS releasable fasteners. There  were no blockouts or backup plates at any of the posts. All guardrail splices were located at the  posts.
			The posts were embedded to a depth of  44 inches and spaced at 12.5 feet. The  Guardrail panels were each 12.5 feet long and mounted such that the top-of-rail  height was 27-5/8 inches. The 187-foot long test section was  adequately anchored at both ends.
			**Crash Testing** The Gregory Mini Spacer W-Beam Barrier  (GMS-WB) was subjected to MASH-08 Test 3-11 using the 5000-pound quad-cab  pickup truck. The test data summary  sheet is enclosed for reference. Upon  impact the barrier deflected 5.0 feet and the vehicle remained upright and in  contact with the barrier a total of 46.8 feet. All occupant risk values were within  acceptable limits.
			Test 3-10 using the 1100C vehicle was  waived because the small passenger car has been shown to have insufficient  energy to cause significant horizontal deflection or vertical movement in the  rail, and that there is little likelihood that it could under-ride the barrier.
			**Findings** You also requested the following variations to be accepted  under MASH-08:
			1)  Single face and double face W-beam versions  (Roadside version as crash tested, and median barrier version with W-beam on  both sides, both using the GMS.)
					a)  The double-face GMS-WB has been previously  tested and found acceptable with 6 foot, 3 inch post spacing, meeting both the  strength (penetration) and severity (occupant risk) criteria. When extrapolating to the 12 foot, 6 inch  post spacing the test with a single rail of W-Beam is the “worst case”  condition for both test conditions: for the strength test it is more likely  that the vehicle would penetrate the single rail barrier while for the severity  test the single rail system is more forgiving.2) GMS-WB for new installations, retrofits, or  repairs of 10 gage or 12 gage W-Beam Systems.
					a)  Ten gage  W-beam is an acceptable alternative for standard 12 gage rail and will be  acceptable.3) GMS-WB at top rail heights  between 27 inches and 32 inches.
					a)  As the  lower height rail was tested with the truck having a greater tendency to  override the barrier, and the higher rail was previously tested at the 6-foot  3-inch post spacing with the small car having a tendency to go under the rail,  the range you requested is acceptable.4)  GMS-WB using W6 x 8.5 steel posts or G4(2W) or G4(RW) timber posts.
					a) The  performance of these guardrail posts has been demonstrated with crash testing  of various barriers and either will be acceptable.5)  Splices  allowed at or between posts.
					a) As  testing was conducted under worst case conditions with splices at posts, splice  location will be acceptable at a post or a gap.6)  With or without backup plates.
					a)  As the  rail releases from the post before the edge of the post can tear the rail,  backup plates are optional.7)  Use of  the Gregory Mini-Spacer on any non-proprietary strong or weak post W-beam with  or without blockout.
					a)   The releasable fastener does not degrade  performance of W-beam systems.8)  GMS-WB with post spacings of 12 feet 6  inches, 6 feet 3 inches, or 3 feet 1.5 inches.
					a)  Testing  has verified standard and double spacing. Halved spacing can be expected to reduce  deflection as noted:2000P
					2270PPost Spacing
					Dynamic  Deflection*
					Dynamic Deflection**12  ft 6  in
					5  ft 6 in
					5 ft 10 in6  ft 3  in
					4 ft 1  in
					4 ft  6 in3  ft 1.5 in
					3 ft  8 in
					3 ft 11 in*Maximum dynamic deflection. The NCHRP Report 350 criteria sets the  “design deflection distance” at the maximum dynamic deflection recorded in  Report 350 test 3-11. From the crash  testing that you performed and your analysis (a method that agrees with a tuned  Barrier VII analysis), you came up with recommended Report 350 test 3-11  (2000P) deflection criteria. You  recommend that the minimum distances at which the face of a GMS installation be  placed from the face of a rigid obstacle (e.g. bridge pier or overhead sign  support) be 1.68m (5 ft 6 in), 1.25m (4 ft 1 in), and 1.12m (3 ft 8 in) for  12’6” (2x), standard 6’3” (1x), 3’ 1-1/2” (1/2 x) post spacing,  respectively.
			**Maximum dynamic deflection. Similarly, for test 3-11 (2270P) as the  deflection criteria you recommend that the minimum distances at which the face  of a GMS installation be placed from the face of a rigid obstacle (e.g. bridge  pier or overhead sign support) be 1.78m (5 ft  10 in), 1.37m (4 ft 6 in), and  1.19m (3 ft 11 in) for 12’6” (2x),  standard 6’3” (1x), 3’ 1 1⁄2” (1/2 x) post spacing, respectively.
			These offsets are based on the “working width” deflections  seen in the crash tests/analysis and include some degree of pickup truck  penetration beyond the vertical plane of the barrier’s dynamic deflection. As with all traffic barriers, larger offset  distances would be required to shield similar features from vehicles with  higher centers of gravity, such as single-unit trucks or busses, because of the  relatively high roll angles seen with these vehicles in rigid and semi-rigid  barrier tests of similar height.
			9)  GMS-WB may be used with W-beam barrier terminals having equal rail  heights.
					a)  Test  experience has shown that interchangeability is acceptable between other  systems and terminals.Because the crash testing met the requirements of the  proposed MASH-08 criteria, the system described above, as well as the  variations 1 through 9, are acceptable for use on the NHS under the range of  conditions tested, when such use is acceptable to a transportation agency.
			Please note the following standard  provisions that apply to the 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 the NCHRP Report  350.
			  To prevent misunderstanding by others,  this letter of acceptance is designated as number B-150B 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 GMS-WB guardrails and median  barriers are patented products and considered proprietary. If proprietary systems 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.
			  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,
						David A. Nicol
						David A. Nicol, P.E.Director, Office of Safety DesignOffice of SafetyEnclosures
			Table 4.1- Summary of Test Results and Conditions
				Images of truck crashing into guardreailGeneral InformationTest AgencySouthwest Research InstituteTest NumberGMS-7Test Date10/30/2007Test Category3/11Test ArticleTypeLongitudinal BarrierInstallation Length57.15 m (187.5 ft)Top-of-Rail Height702 mm (27 5/8 in)Post Spacing3.81 m (12.5 ft)Type of Primary BarrierModified G4(1S)SoilStable, Dry-“Standard” SoilTest VehicleType1⁄2 Ton Quad Cab PickupDesignation2270PModel2003 Dodge Ram 1500 Quad cabMass (kg)2241Inertial Mass (kg)2241Dummy Mass (kg)NAGross Static Mass (kg)2241
					Impact ConditionsSpeed (km/hr)102.3Angle (degrees)23.9Exit ConditionsSpeed (km/hr)60 (calculated)Angle (degrees)18Occupant Risk ValuesImpact Velocity (m/s)x-direction3.3y-direction-4.4Ridedown Accelerations (g's)x-direction-6.6y-direction-7.0
					Test Article DeflectionDynamic1.52 m (5.0 ft)Max. Velhicle Intrusion1.80 m (5.92 ft)Permanent0.53 m (1.75 ft)Vehicle DamageExteriorCDC11LFEW5VDS11-LFQ-3InteriorOCDILF0000000Max. Deform (mm)0Post Impact Vehicle Behavior (limited to events <2.000 seconds)Maximum Roll Angle (degrees)-28.3 @ 0.913 sec.Maximum Pitch Angle (degrees)-12.9 @ 1.224 sec.Maximum Yaw Angle (degrees)54.8 @ 1.190 sec.Graph of truck crashing into guardreail U.S. DEPARTMENT OF TRANSPORTATION

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