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 CC-61C
  
  **Hardware Type:**
            Barrier Terminals and Crash Cushions
                          **Code:**
            CC-61C
                          **Date:**
            04/04/2004
                          **Testing Criteria:**
            NCHRP 350
                          **Manufacturer:**
            Midwest Roadside Safety Facility
                          **Device Description:**
            Single-bolt post for FLEAT/SKT terminals
                          **View PDF:**
            cc61c.pdf (512.93 KB)
    
    Skip to contentUnited States Department of Transportation - Federal Highway AdministrationAugust 20, 2004

Refer to: HSA-10/CC-61C

Dean L. Sicking, PhD., P.E.
Director, Midwest Roadside Safety Facility
W. 328.1 Nebraska Hall
PO Box 880529
Lincoln, NE 68588-0529

Dear Dr. Sicking:

The Federal Highway Administration allowed conditional use of a two-bolt breakaway post with the Sequential Kinking Terminal (SKT) terminal in Ms. Carol Jacoby’s October 30, 2002, acceptance letter CC-61A, but requested an additional test before this post was used with the flared FLEAT terminal. Your March 25, 2004, letter transmitted the results of this additional test as well as a copy of the Midwest Roadside Safety Facility’s report entitled “Performance Evaluation of the FLEAT-MGS End Terminal – NCHRP Test No. 3-35” and my April 5, 2004 letter accepted the two-bolt post design for use with both the SKT and FLEAT W-beam guardrail terminals.

Your March 25 letter included a second test report, entitled “Performance Evaluation of the FLEAT-MGS End Terminal with Redesigned Breakaway Posts and End Anchorage– NCHRP Test No. 3-35 (FLEAT 7).” You subsequently asked Mr. Richard Powers of my staff to delay formal acceptance of both the redesigned breakaway posts used in this test and the redesigned end anchorage. In early August, by telephone, you requested him to proceed with his review and analysis of the modified post design.

For test FLEAT 7, the original FLEAT was modified to connect to your Midwest Guardrail System (MGS), a strong post W-beam barrier that has been successfully tested to NCHRP Report 350 guidelines, but has not yet been submitted for formal FHWA acceptance. To match the design features of the MGS barrier, the FLEAT posts were increased to an above-ground height (breakaway height) of 33.5 inches to attain a top rail height of 31 inches, posts 3 through 6 were fitted with the 6-in wide by 12-in deep x 14-in long routed wood offset blocks used throughout the MGS barrier, and the lead section of W-beam was a 16.67-ft long section of 12-gauge W-beam with five pairs of slots on the upstream end of the rail. Use of this initial length section of rail resulted in all rail splices falling midway between the support posts throughout the terminal and the barrier proper, a key characteristic of the MGS design. However, for this test the two 9/16-inch diameter splice bolts used to connect the top and bottom sections of the breakaway line posts in the earlier design were replaced with a single 3/4-inch diameter x 8-inch long Grade 5 hex bolt. The holes in the splice plate and top post base flanges were increased to 7/8-inch diameter to allow insertion of the larger bolt. Enclosures 1 and 2 show the details of the single-bolt design as tested.

Test 3-35 (FLEAT 7) was conducted on a barrier layout with the FLEAT offset 4 feet from the line of the MGS barrier. The 2000P truck was contained and redirected upright. Enclosure 3 is the test summary page from the aforementioned report. Because the single-bolt hinge allows the post to rotate back with virtually no resistance when struck head-on, you did not conduct either of the standard end-on terminal tests. However, the reduced weak-axis strength of the single-bolt post will likely result in greater intrusion into the system for very shallow angle impacts. Proper end-on performance also depends upon the single bolt being placed in the downstream splice plate/top post flange holes. Users and installers of the single-bolt design need to be aware of these considerations.

Based on the reported test results, I find the single-bolt breakaway post design to be acceptable for use on the National Highway System with both the SKT and the FLEAT W-beam terminals at test level 3. The field performance of both of these terminals should be monitored to verify acceptable crash performance when connected to a standard W-beam design.

Sincerely yours,

(original signed by Richard D. Powers)
for: John R. Baxter
Director, Safety Design
Office of Safety

3 Enclosures

FHWASafety Home | FHWA Home | Feedback

United States Department of Transportation - **Federal Highway Administration** 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