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Bridge Guardrail

State MO
Description Text

Can you
tell me if the MoDOT thrie beam guardrail on BRIDGE using a W6x20 post at 6’-3”
spa. with or without W6x15 steel blockout is acceptable for MASH TL-3?


I believe
our current system is NCHRP 350 TL-3 compliant which can be utilized with or
a steel blockout.


Sanders, P.E.

Development and Support Engineer

Dept. of Transportation

  • Bridge Rails
Other Keywords none
Date December 27, 2017


I believe that the bridge railing system was crash tested under the NCHRP Report No. 230 criteria. Unfortunately, I am unaware of any crash testing under NCHRP Report No. 350 on this exact bridge railing. There may have been a grandfather from 230 to 350** on this bridge railing.


**Memorandum on Crash Testing of Bridge Railings, May 30, 1997, File Designation HNG· 14, Federal Highway Administration (FHWA), Washington. D.C ., 1997.


MASH testing would be recommended for the bridge railing.


The approach guardrail transition (AGT) was largely crash tested under NCHRP 350 and MASH using the Test Level 3 safety performance criteria. The various transition testing programs on similar systems are attached below.


Successful 350 Testing on Similar AGT



Failed 2000P & Passed 820C – Original AGT & Transition Element



Failed 2000P & Failed 2000P – Modified AGT w/ Rubrail



New Transition Element R&D



New Transition Element and Standardized AGT – MASH Testing



New Standardized AGT w/ Curb – MASH Testing




Date January 2, 2018
Attachment MoDOT Midwest MASH Transition Section.pdf

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