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-116
  
  **Hardware Type:**
            Longitudinal Barriers and Bridge Rails
                          **Code:**
            B-116
                          **Date:**
            03/27/2003
                          **Testing Criteria:**
            NCHRP 350
                          **Manufacturer:**
            Midwest Roadside Safety Facility
                          **Device Description:**
            low concrete bridge rail @ TL-2
                          **View PDF:**
            b116.pdf (69.54 KB)
    
    HSA-10/B116

March 27, 2003
HSA-10/B116
Ronald K. Faller, Ph.D., P.E.
Research Assistant Professor
Midwest Roadside Safety Facility
P.O. Box 880601
Lincoln, NE 68588-0601
Dear Dr. Faller:
In your letter dated October 24, 2002, you requested formal
Federal Highway Administration acceptance of a Low Profile Bridge Rail tested
to NCHRP Report 350 test level 2 (TL-2).
Included with your letter were copies of the Midwest Roadside Safety
Facility report dated August 20, 2002, entitled "Development of a Low-Profile
Bridge Rail for Test Level 2 Applications", a VHS video tape documenting the
compliance test, and a CD-ROM containing digital photographs, film footage and
system drawings.
The tested rail was a 508-mm high reinforced concrete "curb"
with a vertical back and a top width of 356 mm to a depth of 152 mm. This width was then transitioned back (on a
1:1 slope) to a 279-mm thickness, which then remained constant to the bridge
deck. These dimensions (and reinforcing
details) are shown in the enclosure to this letter. NCHRP Report 350 test 2-11 was run, with a 2000-kg pickup truck
impacting the rail at 70 km/h and at an angle of 27.1 degrees. The vehicle was contained and redirected. Reported occupant impact velocity and
ridedown accelerations were 6.6 m/s and 8.1 G's, respectively, both values
being less than the preferred maximums suggested in NCHRP Report 350
guidelines. The roll angle of the truck
was 36 degrees. Test 2-10 with the
820-kg car was deemed redundant based on previous tests with similar height
barriers and I agree that that test can be waived in this instance.
The bridge rail described above can be considered an NCHRP
Report 350 test level 2 (TL-2) design and used on the National Highway System
at locations where anticipated impact speeds are in the 70-km/h range.
Although you did not request acceptance of a terminal for
the TL-2 bridge rail in your letter, your research report recommended the use
of a sloped concrete end treatment similar to one which has been previously
accepted at TL-2 based on a series of full-scale crash tests. While that earlier design was deemed
acceptable, the acceptance letter (CC-44, dated March 6, 1998) clearly stated
that in several of the compliance tests, the impacting vehicles rode up onto
the barrier proper or proceeded behind the terminal for distances exceeding 50
meters. While not desirable, these
trajectories may be acceptable if the terrain behind the barrier is both clear
of hazards (or workers) and is reasonably traversable. However, if a sloped terminal is installed
immediately adjacent to a bridge, there is a good chance that an impacting
vehicle may end up in or on whatever feature the structure crosses. Consequently, the sloped terminal should be
used to introduce a bridge rail only when an appropriate length of barrier
proper is installed along the roadway in advance of the structure itself.
Sincerely
yours,
(original signed by Michael S. Griffith)
Michael
S. Griffith
Acting
Director, Office of Safety Design
Office
of Safety
Enclosure 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