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                Safety Eligibility Letter B-224
  
  **Hardware Type:**
            Longitudinal Barriers and Bridge Rails
                          **Code:**
            B-224
                          **Date:**
            12/23/2011
                          **Testing Criteria:**
            NCHRP 350
                          **Manufacturer:**
            Massachusetts / Texas
                          **Device Description:**
            TL-2 Texas T-401 Bridge Rail
                          **View PDF:**
            b224.pdf (457.26 KB)
    
    Safety Eligibility Letter B-224



						
**Download Version**PDF [457 KB]

			DOT logoU.S. Department of Transportation**Federal Highway Administration**

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

			December 23, 2011

			In Reply Refer To: 
			HSST/B-224



			Maura Sullivan 
			  Mass DOT Highway Division 
			  Accelerated Bridge Program 
			  10 Park Plaza, Room 6500 
		    Boston, MA  02116
Dear Ms. Sullivan:
This  letter 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:

  	 T401  (Based on crash test of T4)Type of system:

  	 Bridge  RailingTest Level:

  	 NCHRP Report 350 TL-2 or TL-3Testing conducted by:

  	 Texas Transportation Institute (TTI)Task Force 13 Designator:
      	   SBB09cDate of request:
      	   September 8, 2011Date initially acknowledged:
      	   September 8, 2011Date all information rec'd:
      	   December 8, 2011**Decision:**
The following device is eligible, with details provided  below:
Texas Type T401 Bridge RailingBased on a  review of crash test results and an engineering analysis of the modifications  made on the original railing, the device described herein meets the  crashworthiness 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.
**Description**
  This railing is  33-inches high with an 18-inch concrete parapet and a steel ellipse or  rectangular tube 15 inches above the concrete. It has twin one-inch cut-plate  posts spaced a maximum of 10 ft. apart. It features a bolt anchorage system for  the steel rail posts that may be drilled and epoxy anchored allowing  slip-forming of the concrete parapet. Its parapet is thicker than the T4 rail,  from which its design is derived.
**Requirements**
  Roadside safety devices should meet the guidelines  contained in the NCHRP Report 350 or the American  Association of State Highway and Transportation Officials' Manual for Assessing  Safety Hardware (MASH).  The FHWA  Memorandum "Identifying Acceptable Highway Safety Features" of July 25, 1997  provides further guidance on crash testing requirements of longitudinal  barriers.
**Crash Testing**
  The Texas Type T4 (A) Bridge Rail was tested to NCHRP  Report 350 Test 3-11.  The report is  summarized in the enclosed "Figure 11" from the TTI report.  The railing contained and redirected the  vehicle.  The vehicle did not penetrate,  underride, or override the installation. Maximum permanent deflection of the  rail during the test was 5 mm. No detached elements, fragments, or other debris  were present to penetrate the occupant compartment, or to show potential for  penetrating the occupant compartment, nor to present undue hazard to others in  the area.  Maximum occupant compartment  deformation was 158 mm in the right floor pan to instrument panel location.  The vehicle remained upright during the  collision and after loss of contact with the installation.  The vehicle trajectory may intrude into  adjacent traffic lanes as it came to rest 6.1 m toward traffic lanes.  Longitudinal occupant impact velocity was 8.5  m/s, and the longitudinal ridedown acceleration was -9.7 g's.  Exit angle at loss of contact was 11.3 degrees  which was 46 percent of the impact angle.
Damage to the Texas T4 (A) bridge rail was extensive.  The flange on the impact side of post 4 was  marred and chipped as were the base plate and front bolts.  Both the top and bottom of the rail element  were scarred to a distance of 190 mm from the impact face of the rail.  Structural cracks in the concrete portion of  the rail occurred 400 mm from the center of post 4.  One extended 85 mm down the field side of the  concrete parapet and another radiated from the right rear bolt and extended 95  mm down the rear.  A section of concrete  (200 mm x 390 mm) broke out of the rear of the concrete beam deck under the  bolt on the upstream field side and exposed the bolt.  Maximum dynamic deflection of the rail during  the test was not attainable and maximum permanent deformation of the metal rail  element was 5 mm.  Total length of  contact of the vehicle with the bridge rail was 4.3 m.
Because of the extent of the damage to the railing,  additional static and dynamic testing was done to the basic design of the T4.  The modified railing includes a thicker  concrete parapet and drilled and epoxied bolts to anchor the rail to the top of  the parapet.  The modified design was  designated at the T401, the subject of this letter.
**Findings**
  The Texas Type T4 (A) Bridge Rail successfully contained  and redirected the vehicle which remained upright during and after the  collision.  Improvements to the T4 to  strengthen the concrete parapet and improve the constructability of the steel  railing resulted in the T401 bridge railing. Because these modifications to the T4 do not adversely affect  the crash test performance, the T401 system described in this letter and  enclosures is considered eligible for reimbursement on Federal-aid highway  projects. It should be installed under the range of conditions tested, when  such use is acceptable to a highway agency.
Please note the following standard provisions that apply to FHWA  eligibility letters:
This letter provides a AASHTO/ARTBA/AGC Task  Force 13 designator that should be used for the purpose of the creation of a  new and/or the update of existing Task Force 13 drawing for posting on the  on-line ‘Guide to Standardized Highway Barrier Hardware' currently referenced  in AASHTO Roadside Design Guide.
  This finding of eligibility 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 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 this  letter.
  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 review, and that it  will meet the crashworthiness requirements of the FHWA and the NCHRP Report  350.
  To prevent misunderstanding by others, this letter  of eligibility is designated as number B-224 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.
  This 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 finding of eligibility 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 Michael S. Griffith */*
      
      Michael S. Griffith
  Director, Office of Safety  Technologies
  Office of SafetyEnclosures U.S. DEPARTMENT OF TRANSPORTATION

**Federal Highway Administration**

1200 NEW JERSEY AVENUE, SE

WASHINGTON, DC 20590

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