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                Safety Eligibility Letter B-177
  
  **Hardware Type:**
            Longitudinal Barriers and Bridge Rails
                          **Code:**
            B-177
                          **Date:**
            07/16/2007
                          **Testing Criteria:**
            NCHRP 350
                          **Manufacturer:**
            TGS Trinity Industries
                          **Device Description:**
            Trinity Guardrail Systems (T-31 and T-39 in both US and SI panels and post spacings.)
                          **View PDF:**
            b177.pdf (1.3 MB)
    
    Safety Eligibility Letter B-177

			 
			**Download Version**PDF [827 KB]
			
			DOT logoU.S. Department of Transportation**Federal Highway Administration**
			1200 New Jersey Ave. S.E.Washington, D.C. 20590
			July 16, 2007
			In Reply Refer To: HSSD/B-177
			
			Mr. Brian Smith
				Trinity Highway  Products, LLC
				PO Box   568887 
				Dallas, TX 75356-8887
			Dear Mr. Smith:
			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:Trinity  Guardrail System (TGS)Type of  system:31 inch  strong post w-beam longitudinal barrierTest Level:National Cooperative Highway  Research Program(NCHRP) Report 350 and Manual for  Assessing SafetyHardware 2008 (MASH-08) Test Level 3Testing  conducted by:Texas Transportation  InstituteDate of  request:November  13, 2007Additional  information received:April 28,  2008Date of  completed package:June 20, 2008You requested that we find this system acceptable for use on  the NHS under the provisions of the NCHRP Report 350 “Recommended Procedures  for the Safety Performance Evaluation of Highway Features” and the proposed American Association of State Highway and Transportation  Officials’ 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." FHWA  Memorandum “ACTION: Identifying Acceptable Highway Safety Features” of  July 25, 1997, provides further guidance on crash testing requirements of  longitudinal barriers. You have also  chosen to anticipate the adoption of the 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 the MASH-08 is formally  adopted.
			**Description**The TGS is a non-blocked-out strong  post w-beam longitudinal barrier system that consists of 3.81 m (12 foot 6  inch) long, 12 gage w-beam rails supported on 1.83 m (6 foot 0 inch) long W150 x 12.6 (W6 x 8.5#) standard  (non-weakened) line posts spaced 1.905 m (6 feet 3 inches) on center. Measured from the ground level the heights of  the top of the posts and the top edge of the w-beam are 813 mm (32 inches) and  787 mm (31 inches) respectively. W-beam  rail splices are located at the posts.
			The FHWA previously accepted  Trinity’s 31-inch high non-blocked-out strong post w-beam barrier that used steel  yielding line posts with splices located at mid-span (FHWA Acceptance Letter  B-140 dated November 2, 2005).
			**Crash Testing**Two full scale crash tests were  conducted on a 53 m (175 foot) length of the TGS:
			NCHRP  Report 350 Test 3-10, (820C, 100 km/hr, 20 degrees) and
			  MASH-08  Test 3-11 (2270P, 100 km/hr, 25 degrees)In both tests the rail splices were  located at the posts with no Flange Protector (backup plate) in use. In test No. 1 the rails were attached to the  posts with 16 mm x 44 mm (5/8 x 1 3⁄4 inch) slotted countersunk head bolts that  were previously used in testing the Trinity T-31 and T-39 barrier systems. In test No. 2 the rails were attached to the  posts with 16 mm x 44 mm (5/8 x 2 inch) countersunk head bolts with  an elongated shaft. You plan on using  only the 16 mm x 44 mm (5/8 x 1 3⁄4 inch) slotted  countersunk head bolt as this bolt allowed the rail to release from the post  more readily during testing.
			**Findings**You requested acceptance under both the NCHRP Report 350 and  the MASH-08 criteria. Tests No. 1 and No. 2 noted above and detailed in the  enclosed Test data summary sheets met the test and evaluation criteria of the NCHRP  Report 350 and the Proposed MASH-08, respectively. At our request you provided the overhead view  of test No. 1 that showed the small car redirected by the barrier through a yaw  of 140 degrees. However we found no  evidence of hard snagging on any post and the vehicle trajectory was comparable  to that seen in other accepted barrier systems.
			The MASH-08 test 3-10 of the 1100C impacting at 25 degrees  was waived as previously agreed by the FHWA because of the pair of 3-10 tests  conducted on the T-31 system. Those  tests showed the 820C impact resulted in higher occupant impact velocities and  ridedown accelerations. We concur that  the 820C test is the ‘worst case scenario’ for the TGS as well.
			The Report 350 Test 3-11 was waived as previously agreed by the  FHWA because of the greater impact severity of the 2270 kg pickup truck. Although it is known that the 2000P vehicle is  structurally less stable we concurred in your contention that the heavier truck  would be most likely to fail the system due to increased dynamic deflection.
			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. The maximum dynamic deflection measured in  test 3-11 was 980 mm (38.4 inches) and the ‘working width’ was 1040 mm (40.9  inches.)
			You also requested 2 m post spacing be allowed for use in  countries that follow the metric system, as we permitted you to do on the T-31  and T-39 systems. As the standard USA spacing is  1.905 m we consider the 5 percent additional distance between the posts to be  acceptable.
			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-177 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 TGS is a patented product and considered  proprietary. If proprietary systems are specified by a highway agency for use  on Federal-aid projects, except exempt, non-NHS projects, they: (a) 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,
						Signature of David A. Nicol
						David A. Nicol, P.E.Director, Office of Safety DesignOffice of SafetyEnclosure
			Images of car crashing into guardreailGeneral InformationTest AgencyTexas TransportationTest No.400001-TGS2Test Date06-08-2007Test Category3-10 UpdateTest ArticleTypeLongitudinal BarrierNameTrinity Guardrail System (TGS)Total Installation Length175 ftKey ElementsDescriptionW-Beam on W6x8.5 x 72 inchlong posts, splices at posts, noblockouts, no flange protectorsSoil Type and ConditionStandard Soil, Damp (9.8%)Test VehicleType/Designation820CMake/Model1997 Chevrolet MetroMassCurb1832 lbTest Inertial1830 lbDummy170 lbGross Static2000 lb
					Impact ConditionsSpeed61.1 mi/hAngle19.7 degreesLocation/OrientationBtw Post 11 and 12Exit ConditionsSpeed28.8 mi/hAngle9.3 degreesPost Impact TrajectoryVehicle StabilitySatisfactoryStopping DistanceBtw Post 21 and 226 ft laterally frontVehicle SnaggingNoneVehicle PocketingNonePost-Impact Behavior (during 1.0 sec after impact)Max. Yaw Angle26 degreesMax. Pitch Angle-6 degreesMax. Roll Angle13 degreesTest Article DeflectionsDynamic19.4 inchesPermanent9.6 inchesWorking Width22.2 inches
					Occupant Risk ValuesImpact VelocityLongitudinal28.2 ft/sLateral17.7 ft/sRidedown AccelerationsLongitudinal-120 gsLateral-7.7 gsTHIV23.5PHD13.0 gsMax. 0.050-s AverageLongitudinal-9.7 gsLateral-6.3 gsVertical-2.5 gsVehicle DamageVDS01RFQ4CDC01FREW3Max ExteriorVehicle Crash11.8 inchesOCDIMax. Occupant CompartmentRF0010000Deformation5.5 inches**Figure 6.7. Summary of results for *NCHRP Report 350* test 3-10 on the TGS.**
			Table 4.1 - Summary of Test Results and Conditions
				Images of truck crashing into guardreailGeneral InformationTest AgencyTexas TransportationTest No.400001-TGS1Test Date05-31-2007Test ArticleTypeLongitudinal BarrierNameTrinity Guardrail System (TGS)Total Installation Length175 ftKey ElementsDescriptionW-Beam on W6x8.5 x 72 inchlong posts, splices at posts, noblockouts, no flange protectorsSoil Type and ConditionStandard Soil, Damp (9.8%)Test VehicleType/Designation2270PMake/Model2002 Dodge Ram 1500 PickupMassCurb4726 lbTest Inertial4970 lbDummyNo DummyGross Static4970 lb
					Impact ConditionsSpeed63.3 mi/hAngle23.8 degreesLocation/OrientationBtw Post 11Exit ConditionsSpeed36.6 mi/hAngle18.4 degreesPost Impact TrajectoryVehicle StabilitySatisfactoryStopping Distance175 ft downstream50 ft laterally frontVehicle SnaggingNoneVehicle PocketingNonePost-Impact Behavior (during 1.0 sec after impact)Max. Yaw Angle-37 degreesMax. Pitch Angle2 degreesMax. Roll Angle-13 degreesTest Article DeflectionsDynamic38.4 inchesPermanent31.0 inchesWorking Width40.9 inches
					Occupant Risk ValuesImpact VelocityLongitudinal16.1 ft/sLateral16.7 ft/sRidedown AccelerationsLongitudinal-11.2 gsLateral-7.9 gsTHIV23.5PHD13.0 gsMax. 0.050-s AverageLongitudinal-5.6 gsLateral-6.5 gsVertical-2.5 gsVehicle DamageVDS01RFQ4CDC01FREW3Max ExteriorVehicle Crash19.0 inchesOCDIMax. Occupant CompartmentRF0000000Deformation0.6 inch**Figure 5.7. Summary of the reults for *NCHRP Report 350* Update test 3-11 on the TGS.**
			Image of Trinity W-Beam System**Figure 2.2. Layout of the Trinity Guardrail System (TGS)**
			Image of Trinity W-Beam System**Figure 2.1. Dtails of countersunk bolt.** U.S. DEPARTMENT OF TRANSPORTATION

**Federal Highway Administration**

1200 NEW JERSEY AVENUE, SE

WASHINGTON, DC 20590

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