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31" Guardrail Transition to G4(1S)

State VA
Description Text

As I indicated earlier, we are being directed to accelerate
our transition to MASH w-beam guardrail.  One of the efforts will be to
remove and replace substandard terminals such as the BCT, turn-downs,
etc.  Our plan calls for this to start in November.


We plan on installing a MASH terminal and then transition
back down to the 27 ¾” w-beam for longer runs that still meet the height
requirements.  We developed our transition detail similar to Washington
DOT and Caltrans designs.  Can you look over the detail and let me know if
you have any concerns?


Thanks for your continued assistance.


  • Guardrail
Other Keywords none
Date October 31, 2016
Attachment MGS Standard Transition.pdf


I recently provided recommendations in a draft report (out soon hopefully) that were related to this issue. I just finished evaluated of a transition from guardrail to PCBs. The transition uses MGS, but would need to transition back to G4(1S) in many cases.


I have attached that section of the draft report. It appears that your detail matches up with the second option we had listed.


You may want to consider allowing for some additional MGS between the terminal and the transition to the original guardrail. We have seen that many of the terminals have stopping distances longer than their stated length. For example, some designs have stopping distances for test 3-31 of 50’, but the terminal length is listed as 37.5’. Conservatively, we have recommended not transitioning the height within known stopping distances. It may not be an issue, but it may be simpler just to account for it.


Take a look at the section I sent and let me know if you need anything else. 
Date November 1, 2016
Attachment MGS to G41S transition.pdf

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