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AGT Post Obstruction

Question
State NE
Description Text
Post # 6 has a footing blocking the placement.
The footing is 2’ below the ground.
What can be done with other post spacing to alleviate this? 


Approach Guardrail Transitions (AGTs)



Date November 12, 2015
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Attachment 74000e01.pdf
Response
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I am not a big fan of moving either post #5 or post #6 approximately 8” or more when only placed within a span of 18.75” due to the potential for increased pocketing when striking just upstream from this location and near asymmetric transition segment. Instead, I would rather use the dual-post straddle and beam system that was developed for Erik Emerson and the Wisconsin DOT in a recent research study. Have you considered this system?

 

Now, as a last resort, I maybe could live with the post shift method if the transition were extended more upstream to include another thrie beam panel (6 ft – 3 in.) and more ¼-post spacings to mitigate any concerns with a shifted post of 8”.

 

I will ask that Bob/Scott comment as well. Please let me know if you have any questions related to the information noted above. Thanks!


Date November 19, 2015
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What about 2 more W6x15’s @ 37.5” as in the clip – in the place of the standard posts at ¼ space.

For post 5 of our original sketch fix: the below would span the footing but we would use an additional 6’-3” of thrie beam &  the 31” rail to the right as in our original sketch.

For post 6 fix: this would require moving the last W6x15 8” which would be behind the 6-‘-3” thrie beam

Date November 20, 2015
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Attachment sstr.jpg
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The noted transition below does not have include the transition to the standard AGT that is now used. However and in terms of our prior discussion, one could add a few more ½-post spacings of W6x15, another 6 ft 3 in. segment of thrie to include 12 ft 6 in. of single thrie, then the asymmetric segment, etc. The 37.5 in. span would straddle the hazard. You would still then have Scott’s stiffness transition with 18.75” spacings and design K or L of prior report. Let me know if this makes sense. If not we could sketch on paper a few versions.


Date November 21, 2015
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