|Logged in as: Public User|
Can an asymmetrical (thrie-beam to
Assume that no curbing will be used. And in some cases the MGS portion will then
If this can be done, then we also
Attached are the current standards
|Date||January 31, 2017|
|Attachment||MnDOT Std Plan 611.PDF|
|Attachment||MnDOT Std Plan 614.PDF|
|Attachment||MnDOT Std Plan 695.PDF|
|Response||I have some replies to your questions.
We do believe that the asymmetrical W-to-Thrie transition can be used to connect the bullnose to MGS. Our current recommendation would be that the transition section not be added until the end of rail section no. 4 or post no. 10. This is consistent with the detail that you sent. This guidance was based on previous analysis of the length of the deformed rail in the full-scale crash tests.
If transitioning to the MGS, there will be a need to transition the splices to the mid span as well. We believe that this can be accomplished by placing the first post downstream of the asymmetrical W-to-Thrie transition piece at 1/2 spacing and then using standard spacing from that point on. This would correspond to putting in a post at 1/2 spacing after post no. 11 in your detail and then using standard post spacing afterwards.
One final comment with regards to transition from the bullnose to MGS and then to and AGT. We would recommend a minimum of 25 ft of standard MGS between the bullnose and the start of the MGS upstream stiffness transition.
|Date||February 7, 2017|
Thank you for the response. We just have one more quick question regarding post type (wood to steel) change locations.
We are proposing to change from a wood post (# 10) to steel post (# 11).
Let us know if this post type change location is ok. (See Attached pdf figure).
|Date||February 7, 2017|
I believe that you can start the use of CRT posts at post no. 9 if you wish. The NCHRP 350 bullnose testing with the UBSP posts used the standard steel posts starting at post no. 9.
Thus, I don’t see the use of steel posts at post no. 10 being an issue. We did use 78” long posts in the thrie beam sections rather than the 72” long posts used for the MGS and would recommend those posts in the thrie beam region. We would also recommend that the shorter blockouts used in the bullnose be used throughout the thrie beam region.
|Date||February 13, 2017|
130 Whittier Research Center
2200 Vine Street
Lincoln, NE 68583-0853
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.