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MGS close to retaining wall

State OH
Description Text In this proposed cross section with MGS half post spacing, what do you recommend as minimum spacing between the back for the post and the pile wall? I’m thinking 6 inches shown is too little. If we reduce the shoulder to 3’, we could get at least 1.5’ behind the post. And we could also try 8” blockouts.

Also, could the distance behind the post be reduced further if MGS with quarter post spacing was used?
  • Guardrail
Other Keywords Retaining Wall
Date April 10, 2018
Attachment retaining wall.png


We recommend a 2-ft offset between the post and the wall due to a lack of similar testing.  There is also the possibility of using non-blocked, standard post-spacing MGS to save on space between the road and the wall (just ensure the working width does not extend over the wall.


Recently, we tested a ½-post spacing MGS that was top-mounted to a culvert to MASH TL-3 for the state of Wisconsin (Bob will be presenting these results next week at the Midwest Pooled Fund meeting).  The posts were offset 12” from the headwall, and the system passed.  Thus, it would make sense that the posts could be offset 12” from the wall in your situation. A 12” offset would also satisfy the leave out dimensions established for posts-in-rock under NCHRP Report 350.


Date April 10, 2018

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