Logged in as: Public User

Thrie-beam height tolerances

State IA
Description Text

As a follow-up
to Question #288, was a
decision ever reached about thrie-beam height tolerances for MASH TL-3 levels?
We currently show 32” at the concrete bridge end post and then transition down
to 31” at the w-beam connection on our BA-201,
but a question has come in about an older bridge rail that is lower than 32”
and we’re not sure how low the thire-beam connection can be.


  • Approach Guardrail Transitions
Other Keywords none
Date April 6, 2016


We have addressed this issue in the past for several states. You may want to look at the responses below and see if they address your question. The short answer is that little research has been done on thrie beam transitions at heights below 31”. Thus, there are concerns with the performance as the thrie beam AGT height is reduced.








Let me know if this helps.



Date April 7, 2016

Contact Us:
130 Whittier Research Center
2200 Vine Street
Lincoln, NE 68583-0853
(402) 472-0965
Email: mwrsf@unl.edu
The information contained on the Midwest Roadside Safety Facility (MwRSF) website is subject to change without prior notice. The University of Nebraska and the MwRSF is not responsible or liable, directly or indirectly, for any damage or loss caused or alleged to be caused by or in connection with the use or misuse of or reliance upon any such content, goods, or services available on this site.