View Q&A

Guardrail Adjacent to Culvert Repair

Question
State	KS
Description Text	This is a question regarding the repair of a guardrail on US-56. The existing guardrail is protecting a triple 20'x20' box culvert. The guardrail is non-blocked out on concrete posts. The maintenance repair options we have will result in narrowing of the shoulder or extension of the box culvert to accommodate a low-fill guard rail attachment. Both of these options are not likely for a maintenance activity. Do you know of any designs that allow guardrail posts to be bolted to the outside edge of the culvert headwall? I could not find any details. However a colleague said that he found a little info from West Virginia DOT. The sheet is called "Guardrail Installation on Box Culverts and Bridges" I have not had a chance to look at this yet. Let me know what you find out. Currently we are considering to replace in kind as a maintenance activity based on approved agreement that we have with the FHWA regarding guardrail maintenance. Let me know what your thoughts are.

Question

State

Description Text

This is a question regarding the repair of a guardrail on US-56. The existing guardrail is protecting a triple 20'x20' box culvert. The guardrail is non-blocked out on concrete posts. The maintenance repair options we have will result in narrowing of the shoulder or extension of the box culvert to accommodate a low-fill guard rail attachment. Both of these options are not likely for a maintenance activity. Do you know of any designs that allow guardrail posts to be bolted to the outside edge of the culvert headwall? I could not find any details. However a colleague said that he found a little info from West Virginia DOT. The sheet is called "Guardrail Installation on Box Culverts and Bridges" I have not had a chance to look at this yet.
Let me know what you find out.

Currently we are considering to replace in kind as a maintenance activity based on approved agreement that we have with the FHWA regarding guardrail maintenance.

Let me know what your thoughts are.

System Performance Evaluation
NCHRP 350

System Types
Shield culverts
W-beam Guardrails

Applications
Metal Bridge Rails
Systems to Shield Culverts

System Features

Date December 7, 2007
Previous Views (147) Favorites (0)

Response
Response (active)	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.

Response

Response
(active)

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.

Date December 10, 2007
Previous Views (147) Favorites (0)