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                Safety Eligibility Letter B-106
  
  **Hardware Type:**
            Longitudinal Barriers and Bridge Rails
                          **Code:**
            B-106
                          **Date:**
            09/05/2002
                          **Testing Criteria:**
            NCHRP 350
                          **Manufacturer:**
            Caltrans
                          **Device Description:**
            Thrie-beam transition @TL-4
                          **View PDF:**
            b106.pdf (375.15 KB)
    
    
September 5, 2002
HSA-10/B106
Mr. Rich Peter, Chief
  Roadside Safety Technology Branch
  Materials Engineering and Testing Services
  5600 Folsom Boulevard
  Sacramento, CA 95819-4612
Dear Mr. Peter:
In your July 9 letter to Mr. Frederick G. Wright, former Program Manager for 
  FHWA's Office of Highway Safety, you requested formal acceptance of a Thrie-beam 
  bridge rail transition design that you developed and tested to NCHRP Report 
  350 test level 4 (TL-4).  You noted in your letter that local FHWA acceptance 
  had been granted and included copies of your May 2002 test report “Vehicular 
  Crash Tests of a Nested Thrie-Beam Transition Barrier and crash test videotapes.
The final design consisted of a standard 4130-mm long section of nested Thrie-beam 
  on the traffic side and a single section of Thrie-beam on the field side of 
  the transition. One of the traffic side nested rails was 10-gauge.  The other 
  nested rail and the backside rail were both 12-gauge material.  A 10-gauge transition 
  piece was used between the Thrie-beam and the approach W-beam guardrail, and 
  the next 2211-mm long section of W-beam was also 10-gauge material.  Six 250 
  mm x 250 mm wood posts on 953-mm centers were used to support the transition.  
  The five posts nearest the vertical concrete parapet (with a 125-mm chamfer 
  on its leading edge) were 2440-mm long.  The sixth large post, at the W-beam 
  to transition piece location, was 1830-mm long. These details are shown in the 
  enclosure.
Three tests were successfully conducted on this design:  the 2000-kg pickup 
  truck impacting at a nominal speed of 100 km/h and at 25 degrees with the vehicle 
  centered on the concrete parapet and again with it impacting just upstream from 
  the W-beam to Thrie-beam transition piece, and the 8000-kg single unit truck 
  impacting at 75.5 km/h and 16 degrees approximately 2 m from the concrete parapet.
Based on staff review of the information you provided, I agree that the transition 
  described above meets all evaluation criteria for an NCHRP Report 350 bridge 
  rail transition at test level 4 (TL-4) and it may be used on the National Highway 
  System.  Since it is a non-patented design, I assume that any agency interested 
  in detailed drawings or test results may contact you directly at rich_peter@dot.ca.gov or by telephone 
  at (916) 227-7257.
Sincerely yours,
(original signed by Carol H. Jacoby)
Carol H. Jacoby, P.E.
  Director, Office of Safety Design
Enclosure U.S. DEPARTMENT OF TRANSPORTATION

**Federal Highway Administration**

1200 NEW JERSEY AVENUE, SE

WASHINGTON, DC 20590

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