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I got an interesting question and wasn’t sure if it was appropriate to ask it through the Q/A forum. Feel free to post this there if it makes sense. Minnesota will be venturing into some safety grate designs for culvert aprons. The question of design loads for the grates came up from our bridge office. None of us were sure what these would be. Are you aware of any place where we would look for something like this? If not, what loads has MwRSF considered in the past? I’m aware the research overall for culvert and grates has been stagnant for a long while. Let me know if you would like clarification on my questions.

The last time we looked at culvert grates was under NCHRP 350. At that time, we were looking at a culvert grate on a 3:1 slope. We essentially landed a truck on the grate after exiting the roadway. See report link below.

https://mwrsf.unl.edu/researchhub/files/Report88/TRP-03-196-08.pdf

This report summarized and referenced the previous research related to culvert grates.

The culvert grate sizing used in the research effort was based on AASHTO RDG guidelines for culvert grate sizing. See chapter 3.

To the best of my knowledge that is still the most relevant guidance in this area. It has not been revisited under MASH.

Let me know if you have further questions.

Thanks!