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                Safety Eligibility Letter B-163
  
  **Hardware Type:**
            Longitudinal Barriers and Bridge Rails
                          **Code:**
            B-163
                          **Date:**
            08/30/2007
                          **Testing Criteria:**
            NCHRP 350
                          **Manufacturer:**
            S.I. Story Lumber Co.
                          **Device Description:**
            TimBarrier StreetGuard Plus
                          **View PDF:**
            b163.pdf (1.17 MB)
    
    HSSD/B-163






DOT logo

U.S. Department of Transportation

**Federal Highway Administration**

400 Seventh St., S.W.

Washington, D.C.  20590August 30, 2007

In Reply Refer To:  

HSSD/B-163



Mr.  Charles Coleman

S.I.  Storey Lumber Company, Inc.

285  Sike Storey Road

P.O.  Box 99

Armuchee,  GA 30105

	

Dear Mr. Coleman: 

  In your letter of June 26, 2007,  you requested formal Federal Highway Administration (FHWA) acceptance of  longitudinal barrier called the TimBarrierTM StreetGuard PlusTM  as a National Cooperative Highway Research Program (NCHRP) Report 350  test level 2 (TL-2) device. To support  your request, you provided E-Tech Testing Services, Inc. test reports #296 and  #312 dated August 2006 and May 2007 respectively, entitled “NCHRP Report 350  Crash Test Results for TimBarrier StreetGuard Plus ”. You also provided hard copies of the drawings  and test videos.**Requirements**

Longitudinal  barriers 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. Specific information on acceptance of  aesthetic barriers to NCHRP 350 criteria is found in the FHWA Memorandum “INFORMATION:  National Cooperative Highway Research Program (NCHRP) Report 350 Aesthetic  Barriers and Bridge Rails” of April 9, 2003.**Product  description**

  The  TimBarrierTM StreetGuard PlusTM is designed based upon  the principles of Eastern Federal Lands approved “Steel Backed Timber  Guardrail”, previously accepted to the NCHRP Report 230 criteria. It has been modified, however, to use smaller  components including a standard timber guardrail post, reduced thickness steel  backing, and an engineered splice plate. 

  The  TimBarrier line posts are 152 mm deep x 203 mm wide x 1829 mm long (6”x 8”x  72”) timber orientated with the 203 mm (8”) wide face toward traffic. The line posts support timber rails which are  102 mm deep x 305 mm high x 2426 mm long (4”x 12”x 95-1/2”). A 152 mm deep x 203 mm wide x 254 mm long (6”x  8”x 10”) timber blockout is positioned between the post and the rail. The rail elements are reinforced on the back  side by 6.4 mm thick x 152 mm 

  wide  x 2286 mm long (1/4” x 6”x 90”) steel plates which are attached with (9) 9.5 mm  diameter x 63.5 mm long (0.37”x 2.5”) hex head lag screws. The rails are coupled to the posts and 

blockouts  with 6.4 mm thick x 152 mm wide x 610 mm (1/4” x 6”x 24”) long steel splice  plates having a vertical center relief in the post bolt hole provided by (2)  3.2 mm x 19.1 mm (1/8”x 3/4”) vertical cuts extending up and down from the  centers of the hole edges. The splice  plates are attached to the ends of each adjacent rail with (4) 15.9 mm diameter  x 152 mm (0.63”x 6”) long TimBarrier  carriage bolts with hex nuts and 22 mm (0.87”) plane washers on the front side  and 15.9 mm (0.63”) washers on the backside (8 fasteners per connection). A single 15.9 mm diameter x 292 mm long (0.63”x11.5”) TimBarrier carriage bolt passes through the center of the splice  plate and through the blockout and post and is fastened with an oversized 6.4  mm x 

82.6  mm diameter (1/4”x 3-1/4”) plate washer and hex nut. Design details of TimBarrierTM  StreetGuard PlusTM are provided in Enclosure 1.It  should be noted that the described design incorporates two important  modifications to the initial design which were made after the first test (TL  2-11) was conducted in July 2006. Specifically, in the initial design the rail  was installed 2” (51 mm) lower and came in contact with the test vehicle bumper  which caused excessive torsional loading of the rail element, rotational  failure of the splice plate and “riding up” of the test vehicle. Also, in the initial design the splice plate  did not have a vertical center relief in the post bolt hole and could not tear  through the bolt head upon the impact. Such  design did not allow the rail to properly disengage from the post which was  pushed to the ground.

**Test  article installations**

  For  both tests 2-11 and 2-35, the TimBarrierTM StreetGuard PlusTM  was installed with flared end terminals. The first post in each terminal was a 152 mm  wide x 203 mm deep x 1141 mm long (6”x 8”x 45”) standard CRT timber post  embedded in a 1829 mm (72”) long steel foundation tube. The following 3 posts in each terminal were  typical TimBarrier line posts, however they were positioned in the normal  orientation and provided with BCT type through holes bored in them. A cable anchor box was connected to the  backside of the backing plate on the outboard most rails with (8) 5.9 mm  diameter x 152 mm long (0.23” x 6”) TimBarrier carriage bolts with hex nuts and  22 mm (0.86”) plane washers on the front side and 15.9 mm (0.63”) washers on  the backside. A 1981 mm (78”) long cable  with double 25.4 mm (1”) diameter studded and nutted ends was connected to the  anchor box and passed down and through the CRT post to tension the system. The posts were embedded to 1041 mm (41”) depth  for test 2-11 and 991 mm (39”) depth for test 2-35.**Testing**

  The  NCHRP Report 350 requires that in order for longitudinal barriers to meet TL-2  criteria they must successfully pass tests 2-10 and 2-11. You conducted test 2-11 on the initial design  of TimBarrier StreetGuard Plus which showed some potential to cause ramping of  the test vehicle and, after incorporation of two modifications (increased  installation height and vertical center relief in the post bolt hole in the  splice plate as described above), conducted test 2-35. Critical impact point (CIP) in test 2-11 was  selected 0.6 m upstream of the connection splice at post 13 and in test 2-35 it  was selected at the beginning of Length of Need, 0.5 m downstream of post 2.

You  stated in your request for acceptance letter that test 2-35 validates both the  design changes made as well as the end anchorage loading capacity and that re-running  of test 2-11 is not necessary. You also  stated that because the bottom-rail-to-groundline dimension is the same as the  previously accepted TL-3 Steel-Backed Timber Guardrail, test 3-10 is also  unnecessary.

Despite  the differences in critical impact points and impact angles in tests 2-11 and  2-35 and the fact that the posts in the area of vehicle contact in test 2-35  had different (normal) orientation and were weakened by BCT type through holes  at the ground level, we are willing to agree with that statement. Specifically, due to the flare of the terminal  in test 2-35, the resulting impact angle relative to the rail was 28 degrees  and the actual impact severity was 72.9 kJ, exceeding the nominal impact  severity required for test 2-11. We also  agree that the CIP and the weakened posts in test 2-35 increase the loading  experienced by the rail member, its rotation and the likelihood of pocketing  while CIP and stronger posts in test 2-11 contribute to the greatest likelihood  of occupant compartment deformation and excessive occupant safety loading. Therefore, while the above differences  between the tests 2-11 and 2-35 may alter the barrier performance, we are  willing to agree that both tests, considered conjunctively, are sufficient to  evaluate the overall validity of the system.

In  test 2-11 the test article contained the 2000P vehicle preventing penetration,  underride, and override of the installation. Test article damage was categorized as  "substantial" since three replacement posts and four rail sections  would be needed for repair. The  deformation of the vehicle interior was negligible. Occupant risk factors were within the limits  specified in the NCHRP 350. During  impact the right side of the vehicle rode up on the rail at post 16 and the  right front and rear wheels continued riding along the top of the installation  with the left front and rear wheels rolling along the ground. The vehicle came to rest 25 m downstream of  the point of impact with its right side on top of the installation. Summary of  tests results is presented in Enclosure 2.

Based  on the analysis of test 2-11 results you made two modifications to the initial  design as described above and conducted test 2-35 on the modified design. According to the information you provided the  test article performed successfully in test 2-35. The test article redirected the impacting  vehicle, which did not penetrate, underride, or override the installation and  remained upright during and after the collision period. The exit trajectory of the vehicle center of  gravity was essentially parallel to the installation centerline. The deformation of the occupant compartment  was negligible. The test article damage  was categorized as substantial since three replacement posts and four rail  sections would be needed for repair. The  heaviest piece of debris was a 10.9 kg piece of post that came to rest 4.9 m  behind post 7. The furthest piece of  debris came to rest 12.8 m behind post 10.  Occupant risk factors were within the limits specified in the NCHRP 350.  Summary of tests results is presented in  Enclosure 2.

In  summary we agree that TimBarrierTM StreetGuard PlusTM as  described above meets the appropriate evaluation criteria for NCHRP 350 TL-2  devices. The above system may be used at  all appropriate locations on the National Highway System (NHS) when selected by  the contracting authority, subject to the provisions of Title 23, Code of  Federal Regulations, Section 635.411, as they pertain to proprietary products. Please note that this acceptance is only for  the use of the barrier proper, not for the guardrail terminal. It is also limited to “one faced” 

  applications  only. Also, this acceptance is based on  the reported crash performance of the barrier and is not meant to address its  installation, maintenance or repair characteristics.

**Standard provisions**

Please note the following standard provisions that apply to the  FHWA letters of acceptance:

This acceptance is limited to the  crashworthiness characteristics of the devices 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 device 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 device being marketed is significantly different from the  version that was crash tested, it reserves the right to modify or revoke its  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 they will  meet the crashworthiness requirements of the FHWA and the NCHRP Report 350.

  To prevent misunderstanding by others, this  letter of acceptance, designated as number B-163 shall not be reproduced  except in full. This letter, and the  test documentation upon which this letter is based, is public information. All such letters and documentation may be reviewed  at our office upon request.

  The  TimBarrierTM StreetGuard PlusTM is a patented product and  considered proprietary. If proprietary  devices 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  device for which the applicant is not the patent holder. The acceptance letter is limited to the  crashworthiness characteristics of the candidate device, 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 George E. Rice, Jr.

      George E.  Rice, Jr. 

        Acting  Director, Office of Safety Design

        Office  of SafetyPlan view - Timbarrier Streetguard Plus Rail System 1

Plan view - Timbarrier Streetguard Plus Rail System 2

Plan view - Timbarrier Streetguard Plus Rail System 3

Summary of Test Results and Conditions 1

Summary of Test Results and Conditions 2

Title 23, Code of Federal  Regulations

**§ 635.411   Material or product  selection.**

(a) Federal funds shall not  participate, directly or indirectly, in payment for any premium or royalty on  any patented or proprietary material, specification, or process specifically  set forth in the plans and specifications for a project, unless:

(1) Such patented or  proprietary item is purchased or obtained through competitive bidding with  equally suitable unpatented items; or

(2) The State transportation  department certifies either that such patented or proprietary item is essential  for synchronization with existing highway facilities, or that no equally  suitable alternate exists; or

(3) Such patented or  proprietary item is used for research or for a distinctive type of construction  on relatively short sections of road for experimental purposes.

(b) When there is available  for purchase more than one nonpatented, nonproprietary material, semifinished  or finished article or product that will fulfill the requirements for an item  of work of a project and these available materials or products are judged to be  of satisfactory quality and equally acceptable on the basis of engineering  analysis and the anticipated prices for the related item(s) of work are  estimated to be approximately the same, the PS&E for the project shall  either contain or include by reference the specifications for each such  material or product that is considered acceptable for incorporation in the  work. If the State transportation department wishes to substitute some other  acceptable material or product for the material or product designated by the  successful bidder or bid as the lowest alternate, and such substitution results  in an increase in costs, there will not be Federal-aid participation in any  increase in costs.

(c) A State transportation  department may require a specific material or product when there are other  acceptable materials and products, when such specific choice is approved by the  Division Administrator as being in the public interest. When the Division  Administrator's approval is not obtained, the item will be nonparticipating  unless bidding procedures are used that establish the unit price of each  acceptable alternative. In this case Federal-aid participation will be based on  the lowest price so established.

(d) Appendix A sets forth the  FHWA requirements regarding (1) the specification of alternative types of  culvert pipes, and (2) the number and types of such alternatives which must be  set forth in the specifications for various types of drainage installations.

(e) Reference in  specifications and on plans to single trade name materials will not be approved  on Federal-aid contracts.

(f) In the case of a  design-build project, the following requirements apply: Federal funds shall not  participate, directly or indirectly, in payment for any premium or royalty on  any patented or proprietary material, specification, or process specifically  set forth in the Request for Proposals document unless the conditions of  paragraph (a) of this section are applicable.

[41 FR 36204, Aug. 27, 1976, as amended at 67 FR  75926, Dec. 10, 2002] U.S. DEPARTMENT OF TRANSPORTATION

**Federal Highway Administration**

1200 NEW JERSEY AVENUE, SE

WASHINGTON, DC 20590

202-366-4000Subscribe to email updates
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