USA Banner
  U.S. flag
              An official website of the United States government Here's how you knowOfficial US Government Icon
              **Official websites use .gov**A **.gov** website belongs to an official government organization in the United States.
            Secure Site Icon
              **Secure .gov websites use HTTPS**
                  A **lock** ( A locked padlock ) or **https://** means you’ve safely connected to the .gov website. Share sensitive information only on official, secure websites. 
 U.S. Department of Transportation Icon United States Department of Transportation
 Search DOT
            Search
                    About FHWAFHWA Organization
                Headquarters Offices
                Field Offices
                Strategic Plan
                Business Opportunities
                Staff Directories
                Careers
                Highway History
                Contact UsProgramsAcquisition Management
                Civil Rights
                Federal Lands Highway
                Infrastructure
                Innovative Program Delivery
                Operations
                Planning, Environment, and Realty
                Policy
                Research, Development, and Technology
                Safety
                Browse by TopicsResourcesCore Highway Topics
                Federal Aid Essentials
                Automation
                Complete Streets
                Laws and Regulations
                Policy & Guidance Center
                Section 508
                Publications and Statistics
                Professional Development
                National Highway Institute
                Resource Center
                Accessibility Resource Library
                FHWA Research LibraryNewsroomPress Releases
                Speeches & Testimony
                Photos
                Videos
                Media ContactsMenu FHWA Highway Safety Programs Home
                        Safety
                        Roadway Departure Safety
                        Reduce Crash Severity
                        Hardware Eligibility Letters


            
            In This Section
        Roadway Departure Safety
                Strategic Approach
                                Strategic Plan
                Crash Emphasis Brochures
                Focused Approach
                Noteworthy Practices
                Partner Resources
                Keep Vehicles on the Road
                                Pavement Friction
                Horizontal Curve Safety
                Rumble Strips and Rumble Stripes
                Nighttime Visibility
                Provide for a Safe Recovery
                                SafetyEdge
                Clear Zones
                Reduce Crash Severity
                                Overview
                Hardware Eligibility Letters
                Focus on Reducing Rural Roadway Departures (FoRRRwD)
                                Overview
                All Public Roads
                Proven Countermeasures
                Systemic Approach
                Safety Action Plans
                FoRRRwD Resources
                
                Safety Eligibility Letter B-153
  
  **Hardware Type:**
            Longitudinal Barriers and Bridge Rails
                          **Code:**
            B-153
                          **Date:**
            01/17/2007
                          **Testing Criteria:**
            NCHRP 350
                          **Manufacturer:**
            David Hubbell
                          **Device Description:**
            Aesthetic weak-post timber rail
                          **View PDF:**
            b153.pdf (1.94 MB)
    
    HSSD/B-153



DOT logo
U.S. Department of Transportation
**Federal Highway Administration**
400 Seventh St., S.W.
Washington, D.C.  20590January 17, 2007
In Reply Refer To: HSSD/B-153

Mr. David Hubbell
	P.O.  Box 600
Saranac  Lake, NY 12983
	
Dear  Mr. Hubbell:

Thank you for your letter of June  26, 2007, requesting the Federal Highway Administration (FHWA) acceptance of  your company’s NatureRailTM aesthetic weak-post barrier for use on  the National Highway System (NHS).  Accompanying your letter were reports of crash testing conducted by the  French testing laboratory LEIR and video of the tests. You requested that we find this device  acceptable for use on the NHS use at test level 2 (TL-2) under the provisions  of the National Cooperative Highway Research Program (NCHRP) Report 350  “Recommended Procedures for the Safety Performance Evaluation of Highway  Features” when compared to the successfully tested TL-3 aesthetic “Ironwood”  barrier covered under the FHWA acceptance letters B-56 (dated June 18, 1999),  and B-56A (May 11, 2000) and B-56B (September 5, 2003). You supplied additional information comparing  the NatureRailTM to another tested system on December 19, 2006.
	
**Introduction**
  The FHWA guidance on crash testing  of roadside safety hardware is contained in a memorandum dated July 25, 1997,  titled “INFORMATION: Identifying Acceptable Highway Safety  Features.”
  
Testing was conducted on three NatureRailTM  configurations:
Test SOL/GBS-01/519 **(519)** Standard configuration on 1.5 m  posts on 2 m spacing
	Test SOL/GBS-06/593 **(593)**with additional steel on 2 m  posts on 4m spacing
	Test SOL/GBS-02/744**(744)**with additional steel on 2 m  posts on 1m spacing.Brief descriptions of the devices,  taken from the LEIR test reports, follow:
NatureRailTM **519**
	The system tested was a protective  system made of wood and metal comprising cylindrical posts averaging 180 mm in  diameter and 1,980 mm high as a crash barrier.  Flat 100 x 5 metal rails 4,650 mm in length were used as interior  reinforcement. The crash barriers were  screwed tightly to C100 x 50 x 25 x 5  posts (1,500 mm high). The posts were  paneled with round timber (averaging 160 mm in  diameter and 670 mm high) and rammed into the ground 2 metres apart. The connection between the crash barrier and  the posts was secured using metal spacers (100 x 50 x 650). The connection between the spacers, paneling  and posts was ensured by a class 4.6 screw, a H, M12 nut and an M12 washer.
	
NatureRailTM **593** 
  The system tested was a protective  system made of wood and metal comprising cylindrical posts averaging 180 mm in  diameter and 1,980 mm high as a crash barrier.  Flat 100 x 5 metal rails 4,650 mm in length were used as interior  reinforcement. The crash barriers were  screwed tightly to C100 x 50 x 25 x 5 posts (2,000 mm high). The posts were paneled with round timber  (averaging 160 mm in diameter and 670 mm high) and rammed into the ground 4 metres apart. In order to form an even more rigid  connection between the round wood posts and reinforcement panels, an additional  U100 metal reinforcement element 800 mm in length was screwed behind the crash  barrier in the spaces between posts. The  connection between the crash barrier and the posts was secured using metal  spacers (100 x 50 x 650). The connection  between the crash barrier, spacers and metal reinforcing elements was screwed  using 4 class 4.6 TRCC M16 x 200 screws, 4 H, M16 nuts and 4 M16 washers. The connection between the spacers, paneling  and posts was ensured by a H, M12 x 60 class 4.6 screw, a H, M12 nut and an M12  washer.
  
NatureRailTM **744** 
	The device tested is a wood and  steel safety barrier with obstacle protection.  It consists of C100 posts, 2.00 m in length, beaten into the ground  every 1.00 m. The posts are trimmed with  logs. A set of pre-assembled rails  consisting of two logs – RH and LH (Ø 180 mm, length 1,980 mm) secured to a  flat metal reinforcement (100x, length : 4,650 mm). The wood/metal rails are assembled together  by overlapping. The pre-assembled  assemblies are reinforced by a metal rail C100 x 50 x 25 x 5, length : 5,998  mm, placed at the rear of the logs. The  metal rail is secured to the posts by means of a connection/spacers part. The rails are mounted by means of 4 special  round-head bolts, quality 8.8, M16 x 170, and 4 Ø 18 washers (ext. Ø:40, thk.: 5 mm) and threaded plates M16 200  x 80, thk.:12 mm. This assembly is  secured to a connection piece/spacer by means of 4 M16 x 30 hex screws, four 18  x 5 washers and 4 M16 hex nuts, and two threaded plates M16 200 x 80 x 12. The connection piece/spacer is secured to the  post by means of hex head 12 x 60 screws, a Ø 14 washer and a M12 hex  bolt. The post's wood trim is placed  between the metal support and the connection piece/spacer. The connection between the rear metal  reinforcements is made by means of sleeves C85 x 35 x 16, thk.: 4 mm, length  240 mm and 4 hex head bolts, M12 x 60, 4 washers and 4 nuts.
	
Drawings of these barriers are  enclosed for reference. Also enclosed  are drawings that show the significant differences between the TL-3 Ironwood  barrier and the TL-2 NatureRailTM designs.

**Testing**
  Full-scale automobile testing was  conducted by the Inrets Road Equipment Test Laboratory to EN 1317, N-2  standards.
The CEN tests are summarized in  the table below:
**Findings**
	The results of the CEN  testing indicate that the three tested NatureRailTM configurations perform in a  manner at least comparable to
Test/Product
      Number
    Impact
      Speed
    Impact
      Angle
    Vehicle Mass
    DeflectionMax. Dynamic
    Permanent519
    113.3 km/hr
    20.0 deg
    1430 kg
    1.5 m
    0.56 m593
    112.3 km/hr
    20.0 deg
    1429 kg
    2.1 m
    0.92 m744
    116.4 km/hr
    20.0 deg
    1451 kg
    0.9 m
    0.8 mthe NCHRP Report 350 TL-3 accepted Ironwood  barrier. As you requested the FHWA  acceptance to Report 350 TL-2 criteria we concur that the devices described in  the various requests above and detailed in the enclosed drawings are acceptable  for use on the NHS under TL-2 conditions, when proposed by a highway agency. Acceptance is limited to TL-2 conditions as  testing with the 2000P pick up truck has not been conducted.
Please note the following standard  provisions that apply to the FHWA letters of acceptance:
Our       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-153 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       NatureRailTM is a patented device and is considered       "proprietary." The use of       proprietary devices *specified by a highway agency* for use on       Federal-aid projects must meet one of the following criteria: (a) it must       be supplied through competitive bidding with equally suitable  unpatented items; (b) the highway agency must certify that it is 
  essential for synchronization with existing highway  facilities or that no equally suitable alternative exists or; (c) it 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, a copy of which is enclosed.
  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 John R. Baxter
			John R. Baxter, P.E.
				Director, Office of Safety Design
				Office of SafetyEnclosures U.S. DEPARTMENT OF TRANSPORTATION

**Federal Highway Administration**

1200 NEW JERSEY AVENUE, SE

WASHINGTON, DC 20590

202-366-4000Subscribe to email updates
                    About
  

        
              About FHWA
                Careers
                Org Chart
                Staff Directories
                Work with UsPrograms
  

        
              Acquisition Management
                Civil Rights
                Federal Lands Highway
                Infrastructure
                Innovative Program Delivery
                Operations
                Planning, Environment, and Realty
                Policy
                Research, Development, and Technology
                SafetyPolicies, Rights, Legal
  

        
              About DOT
                Accessibility
                Budget and Performance
                Civil Rights
                FOIA
                Information Quality
                No FEAR Act
                Office of Inspector General
                Privacy Policy
                USA.gov
                Web Policies and Notices
                Web StandardsNews & Events
  

        
              Newsroom
                Press Releases
                Speeches & Testimony
                Media Contacts
                Connect with Us