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TL-4 Thrie Beam Barrier

State WV
Description Text I’m trying to contain a perpetual problem of tractor trailers with nested Thrie beam, reduced post spacing and anything short of a concrete barrier wall. The location is about 1900LF so cost isn’t a primary concern, we’re after TL-4 performance or better.

Was there any nesting of Thrie Beam considered in the development of the Bullnose? Or do You know of anyone testing these applications?

From the RDG, pasted below, is a summary of deflections from simulations for my interest. I would like to propose Run number 14 but sure wish I had actual testing to base it on. Run 18 doesn’t produce much benefit for twice the post.

Any info on testing or other input would be much appreciated.
  • Guardrail
Other Keywords Thrie Beam
Date November 25, 2015
Attachment rdg table.png


To the best of my knowledge, no one has evaluated any thrie beam barriers to MASH TL-4. TTI previously tested a 34” tall modified thrie beam system to NCHRP 350 TL-4. See attached. I believe that NUCOR had and NU-Guard W-beam barrier and Trinity had a T-39 barrier that were tested to NCHRP 350 TL-4.


NJDOT has contacted us regarding evaluation of the 34” tall modified thrie beam system to MASH TL-4, but it has not been formally put into a proposal. Additionally, we have had some interest from several states regarding adopting the MGS into a TL-4 system that potentially used thrie beam. However, that has not gotten priority for funding yet. We think the potential to do this exists.


TTI did test the standard G9 thrie beam system to MASH under 22-14(3). The system failed to meet MASH in that test with a 2270P vehicle due to rollover. This system used full length timber blockouts. We believe that the use of shortened timber blockouts would have improved the performance of that system. Our previous research on the bullnose and other transition has shown that the shorter thrie beam blockouts improve capture and stability.


In terms of the barrier in Run 18 below, this system would represent a very stiff thrie beam barrier system based on the post spacing and nested rail. This would essentially be as stiff as some of the thrie beam AGT’s. That said, we would recommend the use of the shorter blockouts mentioned above for this system as well. 

Date November 26, 2015
Attachment 99065.pdf

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