View Q&A

I
am working on upgrading VDOT’s guardrail systems to the MGS and I cannot find
the Thrie Beam Transition drawings that are cited in the FHWA approval letter
B-214.

Would
you be able to send me the drawings and crash test reports or point me to where
I can find them on the Midwest website?

Thank
you for your time.

FHWA letter no. B-214 refers to the downstream portion of the Thrie Beam Approach Guardrail Transition attached to a concrete parapet. In this system, a 4” curb is required for now until other R&D is successfully completed. The report for this testing effort is attached, which corresponded to work performed under the NCHRP study to develop the MASH document.

In addition, it should be noted that the upstream portion of the transition was not tested in this study. Further R&D was later performed to develop, test, and evaluate the upstream stiffness transition. I will need to send you up to four or more additional reports that address that portion of the AGT system. That information will come early next week after the holiday.

I sincerely appreciate the information.  Do you see any issue with this same transition being used with an F shape or vertical face concrete parapet?

Personally, I do not think that it is an issue as long as you ensure that the end cannot be snagged by vehicles. We are working on a standardized buttress that can be used with all AGTs. Also, the upstream and downstream regions would now be required to properly transition stiffness from the semi-rigid rail to the rigid buttress.