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                Safety Eligibility Letter B-146
  
  **Hardware Type:**
            Longitudinal Barriers and Bridge Rails
                          **Code:**
            B-146
                          **Date:**
            07/17/2008
                          **Testing Criteria:**
            NCHRP 350
                          **Manufacturer:**
            New England Transp. Consort.
                          **Device Description:**
            Transitions for 3 NETC bridge rails
                          **View PDF:**
            b146.pdf (5.07 MB)
    
    Safety Eligibility Letter B-146

			 
			**Download Version**PDF [5.27 MB]
			
			DOT logoU.S. Department of Transportation**Federal Highway Administration**
			1200 New Jersey Ave. S.E.Washington, D.C. 20590
			July 17, 2008
			In Reply Refer To: HSSD/B-146
			
			Mr. Gerald M. McCarthy, Coordinator
				New England Transportation Consortium
				c/o Advanced Technology & Manufacturing Center
				University of Massachusetts Dartmouth
				151 Martine Street
			Fall River, MA 02723
				
			Dear Mr. McCarthy:
			This letter is in response to your request for the Federal  Highway Administration (FHWA) acceptance of the New England Transportation  Consortium (NETC) roadside safety system for use on the National Highway System  (NHS).
			Name of  systems:
				1) NETC  New Hampshire T2 Bridge Rail Transition
					2) NETC  New Hampshire T4 Bridge Rail Transition
					3) NETC  Massachusetts End Wall Transition to S3-TL4 Bridge Rail with Sidewalk
					4) NETC  Massachusetts End Wall Transition to S3-TL4 Bridge Rail Curb-MountedType of  systems:
				1&2) W- to  Thrie-Beam Transition direct to beam-and-post bridgerail
					3&4) W- to Thrie-Beam  Transition to concrete end wallTest  Level:
				1&2)  National Cooperative Highway Research Program (NCHRP) Report 350 Test Level 3  (TL-3)
					3&4) NCHRP  Report 350 TL-4Testing  conducted by: Texas Transportation Institute (TTI)
					Date of  request: February 1, 2006
					Date of  completed package: August 29, 2007 (NETC), June 26, 2008 (TTI)
			You requested that we find these systems acceptable for use  on the NHS under the provisions of the NCHRP Report 350 “Recommended Procedures  for the Safety Performance Evaluation of Highway Features.” We appreciate your patience and cooperation  while finalizing this acceptance package.
			**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.
			**Description**In the current project, the NETC developed bridge rail  transitions for two bridge rail systems and for a concrete end wall, and  desired to crash test them to TL-3 requirements of the NCHRP Report 350. Four transitions were developed:
			Transition  to the 2-Bar steel bridge rail with approach curb.
				Transition  to the 4-Bar steel bridge rail mounted on a sidewalk.
				Transition  to the concrete end wall with approach curb.
				Transition  to the concrete end wall mounted behind a sidewalk.Transitions #1 and #2 were developed by New Hampshire  Department of Transportation (NHDOT) and transitions #3 and #4 by Massachusetts  Highway Department (MHD). The MHD  transitions were designed for use with various bridge rail systems beyond the  end wall.
			Our office reviewed the four transitions and determined that  two crash tests were required.
			Test 3-21 on transition #1 to the 2-bar steel bridge rail  with approach curb for TL-3.
				Test 3-21 on transition #4 to the concrete end wall  behind a sidewalk for TL-4.The FHWA accepted transition #3 to the concrete end wall  with approach curb for TL-3 based on crash tests of similar systems already  performed by others, and will accept transition #2 to the 4-bar steel bridge  rail mounted on a sidewalk pending successful testing of transition #1 to the 2-bar steel bridge rail system with approach curb.
			The NETC decided that if the first test (using the 2000P  vehicle) on transition #4 to a concrete end wall mounted behind a sidewalk was  successful a TL-4 test with a single-unit truck (8000 kg vehicle) would be  performed. If transition #4 was  successful for TL-4, the FHWA indicated that they would accept transition #3  with an approach curb for TL-4 without testing.
			Brief descriptions of the transitions follow:
			**New Hampshire  Transitions**The NETC New Hampshire transition consisted of standard  W-beam guardrail attached to a symmetric 10-gage W-beam to Thrie-beam  transition section, attached to nested 12-gage Thrie beam, connected to the two  tube transition rail by means of a Thrie-beam terminal connector. The two tube  transition rails are the same tubular elements used in the bridge rail. A TS 8 x 4 x 5/16 rail element was attached to the top of the  W6 x 25 steel posts at a height of 34 inches above the pavement surface (to the top of the  rail) with two 6-inch long, 3/4-inch diameter round headed bolts. The TS 4 x 4 x 1/4 bottom rail was attached to  the posts at a height of 20 inches with similar bolts. Wood posts throughout the transition were 6  inches x 8 inches x 7 feet long. The  seven wood posts adjacent to the tubular transition rail were installed 18-3/4  inches on center, and the remainder of the posts in the transition were  installed 37-1/2 inches on center. Posts  in the w-beam section were installed at 6 foot 3-inch centers. The upstream end of the guardrail was anchored  with an ET terminal. A 7-inch tall  simulated granite curb was installed throughout the transition and extended in  front of the rail tubes by 6 inches, and in front of the Thrie-beam by 1-1/4  inches.
			**Massachusetts Transitions**The Massachusetts S3-TL4 Steel Bridge Railing system is a  beam and post system consisting of three tubular steel rail elements mounted on  steel wide flange posts bolted to the concrete deck/sidewalk. It was mounted on a sidewalk a distance of 61  inches from the face of an 8-inch high curb.  The bridge railing was attached to a concrete end wall that is part of  the bridge abutment. The end wall flares  away from the face by 8.8 inches over a distance of 2-feet, 10 inches. A  collapsing tube assembly is located in this flared area. The Thrie-beam transition was attached to the  straight portion of the concrete end wall with a Thrie-beam end shoe. Two sections of 12 gage Thrie-beam were nested  and attached to the end shoe and wood support posts. Posts 1 through 4 were 6 x 8-inch x 7-foot  long with 18-inch long blockouts of the same section, spaced 1-1/2 feet on  center. Posts 5 and 6 were 6x8-inch x  6.5-foot long, with 18-inch blockouts (6 x 8) and spaced 3 feet on center. Post 7 was 6x8-inch, 6.5-foot long with a  14-inch blockout (6 x 8). A 10-gage  symmetric Thrie-beam to W-beam transition was mounted on posts 5, 6, and  7. The sidewalk transitioned from 8  inches tall to 6 inches tall at post 8.
			**Testing**Full-scale truck testing was conducted on these transitions,  as summarized in the tables below and detailed in the enclosed Crash Test Data  Sheets for reference. The New Hampshire  transition was tested to TL-3, whereas the Massachusetts transition was tested  to TL-4.
			Test Number
                Test 3-21
                401181-1
                Test 4-21
                401181-2
                Test 4-22 
                401181-3Transition
                New Hampshire
                Massachusetts
                MassachusettsCritical Impact Point Location
                1635 mm from 
                1st    bridgerail post
                1570 mm from 
                start of wall slope
                1570 mm from 
                start of wall slopeMass of Test Vehicle
                2135 kg
                (2000P)
                2108 kg
                (2000P)
                8106 kg
                (8000S)Impact Speed
                102.3 km/hr
                101.2
                82.2Impact Angle
                24.9 degrees
                25.2 degrees
                13.6 degreesOccupant Impact Velocity
                5.2 mps long.
                7.5 mps lat.
                5.1 mps long. 
                6.6 mps lat.
                2.5 mps long.
                3.0 mps lat.Maximum Ridedown*
                -8.3 g’s long. 
                13.5 g’s lat.
                -19.3g’s long.
                17.4g’s lat.
                -4.5 g’s long.
                7.4 g’s lat.Working Width
                580 mm
                450 mm
                539 mmMax. Occup. Deform.**
                44 mm
                104 mm
                N/A*Maximum Ridedown: maximum longitudinal and lateral ridedown  accelerations
			  **Max. Occup. Deform.: maximum occupant compartment  deformation
			****
			**Findings**
			  In all three impacts, the test vehicles were smoothly  redirected by the barrier, with maximum roll angles quite low or  negligible. The results of the testing  met the FHWA requirements and, therefore, the transitions described above and detailed  in the enclosed drawings are acceptable for use on the NHS under the range of  conditions tested, when proposed by a highway agency.
			**Findings**
			  The systems described in the various  requests above and detailed in the enclosed drawings are acceptable for use on  the NHS under the range of conditions tested, when such use is acceptable to a  highway agency. Specifically, the  following scenarios are acceptable:
			 New  Hampshire Transition to the 2-Bar steel bridge rail with approach curb.
				New  Hampshire Transition to the 4-Bar steel bridge rail mounted on a sidewalk.
				Massachusetts  Transition to the concrete end wall with approach curb.
				Massachusetts  Transition to the concrete end wall mounted behind a sidewalk.Please note that system #4 requires  that either there be an existing sidewalk on the approach to the bridge, or  that a gradual transition from the shoulder grade to the sidewalk is provided  in conjunction with the transition.
			Please also 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.
			  Users should ensure 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-146 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 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 Safety U.S. DEPARTMENT OF TRANSPORTATION

**Federal Highway Administration**

1200 NEW JERSEY AVENUE, SE

WASHINGTON, DC 20590

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