Logged in as: Public User

Installation of MGS Long Span on Arched Culvert

State WI
Description Text We have an installation proposed for the MGS long span across an arched culvert. The long span was chosen as the arched culvert limited the embedment depth. 

However, the culvert has a secondary issue in that the CRT posts are against the culvert headwall. 

What are your thoughts on this type of installation?
  • Guardrail
Other Keywords Long Span
Date May 2, 2016
Attachment sd-14b43 B-47-212.pdf


We are concerned that placing the CRT post against the headwall may adversely affect the performance of the breakaway post and the overall behavior of the long span. CRT’s do dissipate some energy through soil rotation and placement of the post against the headwall will affect that rotation significantly.


In previous situations like this we have recommended a minimum offset of 1 ft between the back of the post and the headwall to allow for that rotation.


The only other option I can think of is to use the MGS weak post system. However, it is unlikely that we can get those posts embedded sufficiently over the top of the culvert arch. Thus you would need to move the line of the guardrail closer to the slope and attach the weak posts to the culvert directly.


Date May 5, 2016

Contact Us:
130 Whittier Research Center
2200 Vine Street
Lincoln, NE 68583-0853
(402) 472-0965
Email: mwrsf@unl.edu
The information contained on the Midwest Roadside Safety Facility (MwRSF) website is subject to change without prior notice. The University of Nebraska and the MwRSF is not responsible or liable, directly or indirectly, for any damage or loss caused or alleged to be caused by or in connection with the use or misuse of or reliance upon any such content, goods, or services available on this site.