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ADOT Long Span

Question
State AZ
Description Text

Attached is our draft of the MGS Long Span Guardrail.  We basically allow for one, two or three posts to be eliminated within the 25' maximum span. We call for the 3 CRT posts on each end when any posts are eliminated- would this still be prudent when only one or two posts are skipped?  We also allow for 25' guardrail sections so the splice would be eliminated at midspan wherever it happens to fall in the guardrail run. We assume this also applies to the normal MGS guardrail runs when 25' rail elements are used.  We would appreciate if you could take a look and provide any comments you feel appropriate. 

Keywords
  • Guardrail
Other Keywords none
Date December 7, 2010
Attachment c10062.pdf


Response
Response

When one, two, or three posts are removed in a row of MGS, MwRSF still recommends that three MGS CRT posts be utilized on the upstream and downstream sides of the 12.5 ft, 18.75 ft, and 25 ft unsupported lengths. The span could be accommodated with 25 ft long guardrail segments where the rail splice does not occur at the post locations. The CRT posts were modified for MGS Long-Span applications by raising the hole locations to account for higher rail heights. For metric-height guardrail, different CRT posts were used for long-span applications. As such, CRT posts for the MGS long-span uses different hole locations than those placed in the CRT posts for metric-height W-beam long-span applications. It may have been more clear if we had referred to the posts as MGS CRT posts or 31" guardrail CRT posts. As long as you provide dimensions, it should not be an issue. You might consider showing the two holes in the six posts adjacent to the long span in PLAN and ELEVATION views.

 

As a minor point, the guardrail posts appear to be square in the PLAN view. Also, there are some extra dashed lines in PLAN view across vertical surface between post and blockout " not sure if those are nails or something else. May also want to add barrier height to ELEVATION view.

Date December 8, 2010


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