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Bridge and Roadway Design are reviewing the final report for the Approach Guardrail Transition Retrofit to Existing Buttresses project. We had a question about the Hex Nuts that are welded to the plate. Bridge noted that there would be issues welding these to the plate, but it would be acceptable if they were only tack welded onto the plate. Do you think this would be acceptable? It looks like the only purpose of these nuts is to hold the upstream bolts in place, and they aren’t providing any clamping of the plate to the buttress.

The fabricator we work with also would prefer to use a 1/4” thick plate instead of 3/16” so the plate doesn’t warp when welding. Would you foresee any issues increasing the thickness of the plate?

You are correct.  The nuts on the back-side of the plate are to hold the bolts in place.  The welds only need to be strong enough to hold them in place.  

Increasing the thickness of the plate would not create any structural issues with the end plate assembly.  Normally, there would be some snag concerns with ¼” thick plate, but as long as the upstream edge is beveled/chamfered, there should not be any problems.