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Bob,  I have a question regarding guardrail attached to a box culvert.  I am sure that the system which is designed for shallow-fill situations where there is not enough depth to properly embed standard guardrail posts in the ground has had testing done.  I am having a little bit of an issue finding some exact reports out there where satisfactory passing tests were conducted on such configurations. 

Could you please point me in the right direction on guardrail posts attached to box culverts – box culvert guardrail?

There are several options for guardrail over culverts.

If you are thinking of the strong post option, we tested on to MASG recently. The report is given below.

https://mwrsf.unl.edu/researchhub/files/Report409/TRP-03-383-20-R1.pdf

TTI has a similar system.

https://www.roadsidepooledfund.org/wp-content/uploads/2011/01/405160-23-2-box-culvert-rev2.pdf

We also have worked on several weak post options for guardrail over culverts. These are popular with some states as well. They are summarized in the attached paper.

Thanks!

This is very helpful.  The options for guardrail over culverts are for “NEW” constructed culverts correct?

We have a situation where we are trying to figure out guardrail options for a box culvert but, we were thinking that the guardrail over culvert would only be applicable to “NEW” construction not adding it to an existing culvert.  It’s an overlay job and the designer is constrained due to low fill over the culvert not allowing for 6’ or 8’ posts to be driven.  Rehabbing the culvert to anchor in/bolt in the guardrail would not be the same as the tested options that were done with “new” construction correct?

It would depend on the state of the culvert. These could potentially be retrofitted to existing culverts. If you are concerned with the strength for anchoring, the weak post options may be preferrable as they will reduce the demand on the culvert.

There are also long span options if the culvert you are crossing can be spanned in less than 25’.

Thanks!