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Thrie Beam to MGS W-beam

Question
State IN
Description Text

I was looking for a possible quick response, is it acceptable to transition standard thrie beam to MGS w-beam with an asymmetric thrie beam to w-beam transition (10 or 12 gauge)?



MASH
TL-3

Stiffness and Height Transitions
Thrie Beam Guardrails
W-beam Guardrails


Transition and Attachment Structures

Date October 10, 2023
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Response
Response
(active)

That is acceptable. We recommend the 10 gauge part for transitioning from MGS to thrie beam AGT’s due to the increased stiffness in the transition region. Previous testing would suggest that the 12 gauge part would not be strong enough for that application.

 

If you are simply transitioning from MGS to standard thrie beam, we have typically denoted the use of the 10 gauge part as shown below. We have given guidance on transitioning from the thrie beam bullnose and the modified thrie beam to MGS.

 

While the 12 gauge part may work in that situation, we have not evaluated that part through crash testing. We have observed some issues with MGS rail rupture when the front of a small car wedges underneath the rail and pushes upward. This can put combined loading into the rail element and lead to rail rupture in certain system we have tested like the MGS with omitted post over curbs. As such, we have continued to recommend the 10 gauge part for all these transitions. We are also unaware that any 12 gauge versions of that part exist as it would not work for the majority of installations.

 

Let me know if you need anything else.

 

Thanks!


Date October 11, 2023
Previous Views (87) Favorites (0)
Attachment w-thrie-2.jpg Attachment W-thrie1.jpg