1. It appears that there is some room between the edge of the roadway and the culvert edge. As such, it would appear that you could install the guardrail attached to the top of the culvert previously designed by MwRSF through the pooled fund. However, if you cannot move the guardrail in, then that may not be a viable option.
2. No 350 approved or tested design exist that we know of consisting of posts mounted to the side or edge of the culvert. I looked at the West Virginia designs, but I have never seen testing of those designs. The Pooled Fund sponsored several studies related to MASH crashworthy treatments for guardrail adjacent to and spanning culverts. Besides long-span systems, top-mounted and side-mounted culvert systems have been evaluated to MASH:
https://mwrsf.unl.edu/reportResult.php?reportId=409
https://mwrsf.unl.edu/reportResult.php?reportId=469
https://mwrsf.unl.edu/reportResult.php?reportId=362
https://mwrsf.unl.edu/reportResult.php?reportId=293
The MGS bridge rail, which uses side-mounted weak posts, is another option if the culvert structure is approximately equivalent to the bridge deck design shown in the MGS Bridge Rail standard plans:
https://mwrsf.unl.edu/reportResult.php?reportId=53
3. Another option would be to install a steel bridge rail on the culvert. There are several steel bridge rail options with side mounted posts. The two issues with this option are ensuring that the culvert structure has sufficient capacity for mounting the bridge posts, and the steel bridge rail would require an approach transition.
4. This problem would be a good extension of the current pooled fund project to develop an MGS bridge railing that was funded last year. If the MGS bridge railing development is successful, it would be fairly straightforward to develop the technology to culvert applications as a second phase of the project.
I hope this addresses some of your questions. Let me know if you need more information or if I forgot to address something.
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