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Low Profile Barrier Question

Question
State KS
Description Text

I received the email below. I believe the short answer is no, this barrier was only evaluated under NCHRP 350 for TL-2 applications but I thought I would just confirm with you. Also, I know there probably hasn’t been a lot of MASH testing on TL-2 concrete barriers but if anything comes to mind that I can point Steven to, please send that information or contact.



 



Thank you,







Company: Basis Partners



Email: steven.vg@basisp.com



Message:

I'm a civil engineer looking for low-profile barrier designs that a local municipality in Colorado can use on low-speed residential streets. My company doesn't have any business in Kansas, but I found KDOT Standard Detail RD625B and it has piqued my interest. This shape appears to match the precast MASH-tested shape that TxDOT recently tested. Unlike TxDOT, this KDOT standard is meant to be cast-in-place and permanent, which is exactly what I'm looking for. Do you have documentation that shows that the KDOT low profile barrier design is MASH TL-2 compliant? I really appreciate any info you can provide!



 



MASH
TL-2

Permanent Concrete Barriers



Date September 23, 2022
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Attachment rd625b.pdf Attachment TRP-03-109-02.pdf
Response
Response
(active)

You are correct that the attached barrier has only been evaluated for TL-2 applications.

 

With that said, we recently developed a TL-2 parapet and bike rail system for Iowa that included a MASH TL-2 parapet design - https://mwrsf.unl.edu/researchhub/files/Report385/TRP-03-408-20.pdf

 

That parapet was a vertical parapet that was 24” tall by 10” wide and used #4 stirrups at 24” spacing with four #4 longitudinal bars.

 

The NCHRP 350 design you attached was 20” tall by 11” wide at the base/14” wide at the top and used #3 stirrups at 24” spacing with seven #3 longitudinal bars. I have not run a strength analysis to check this barrier with increased height against the MASH TL-2 parapet design.

 

A couple of options exist.

 

  1. You could use the vertical parapet from the Iowa study.
  2. You could take the older 350 design and increase the height to 24” and increased the stirrups and longitudinal steel to #4 bars. This would make it stronger than the tested MASH TL-2 parapet.
  3. If you really want to use the older 350 design with its existing reinforcement and increase the height to 24”, we would need to run a strength analysis to verify its capacity.

 

Let me know if that helps. I think that option 1 may be the simplest, but that would be up to the end users.

 

Thanks


Date September 24, 2022
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Attachment TL-2 Parapet.jpg