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Modified MGS Bridge Rail

Question
State IA
Description Text  

We are developing a project where we are proposing to use a side-mounted version of the MGS bridge rail on a 17" thick slab bridge that is located on the NHS.  Please review the attached memo, detail, and analysis and provide any comments or concerns.  Note: adhesive anchor values are from the HILTI Product Technical Guide for the HIT-RE 500-SD Epoxy Adhesive Anchoring System.

 

I'm curious whether you think this minor change from the tested system would require approval from FHWA. 

 

Also, I'm open to any suggestions you might have!

 

Keywords
  • Bridge Rails
Other Keywords none
Date November 9, 2011
Attachment Floyd_GuardrailRetrofit_detail.pdf
Attachment Floyd_GuardrailRetrofit_memo.pdf
Attachment FloydBarrierRailSteel_Analysis.xlsb


Response
Response

 

 

As Dr. Faller has indicated, we are currently in the process of adapting the side-mounted, weak post MGS system to culvert headwalls.  The headwall we are attaching to is 18 in. in height.  Thus, our current study is very similar to your situation.  In fact, one of the 3 design concepts we are working with is very similar to the one you have proposed (we only use 4 attachment bolts were you have used 6).

 

My first question to you is... How soon do you need this system?  I ask because we will be testing and evaluating our design concepts relatively soon (hopefully spring of 2012).  If that timeline would work for you, I would recommend waiting for these test results and utilizing our tested side-mounted design configuration.   If you need an answer quicker than that, we can take a close look at your proposed design.

Date November 10, 2011


Response
Response  

If we were to wait and incorporate your system, do you see any potential issues with the fact that our slab is one inch shallower (17" vs. 18") than what you will be testing with?

 

Date November 10, 2011


Response
Response

 

 

If our side-mounted design proves to cause no significant damage to the culvert headwall, I do not see the 1" difference in thickness/height causing any issues.  The current design does not extend to the bottom of the 18" tall headwall, thus all components would be the same for your situation.

Date November 10, 2011


Response
Response

I'll check with our Bridge Office and see if they'd like to hold off for awhile.

 

 

Date November 10, 2011


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