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.
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