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Mash working width values for temporary barrier

Question
State WI
Description Text

I am in the process of updating the
working width information for out temporary barrier to MASH.  So I have to
do some adjustment of the NCHRP test to MASH.



 



Could you take a look at what I have
to see if I am on the right track?

Keywords
  • Temporary Barriers
Other Keywords none
Date April 23, 2015
Attachment Temp barrier working width.pdf


Response
Response I have looked through the detail and have the following comments. In general, they look acceptable.

1. For the free-standing barrier critical location, the MASH TL-3 working width is 8.5 ft rather than the 6’-9” shown.
2. For the asphalt tie-down, the working width shown for NCHRP 350 are based on the testing we conducted adjacent to a 3’ vertical drop-off that moved a significant section of supporting asphalt and soil. If used farther from the drop-off or with a less severe drop-off, it is expected that the deflections of the asphalt pin system would only be marginally larger than that of the bolted tie-down.
3. For the asphalt tie-down, the working width shown for MASH is currently unknown. Increasing it slightly as you have to account for the higher impact severities in MASH is rational, but it is difficult to say how accurate it may be.
4. Similarly, for the bolted tie-down, the working width shown for MASH is currently unknown.

Thanks 
Date May 6, 2015


Response
Response

If the DOTs have to go to MASH.  It would probably be a good idea for MwRSF to come up with recommendations on what the working widths should be ( until we test the alternatives to MASH).  You are probably going to be asked the same question over and over and a consistent answer would help all the states.

I attached a spreadsheet I put together to do the calculations an pick a “rational” number.  I’m not saying it is right, but this looks to be the direction I’m heading in.

Date May 11, 2015


Response
Response

I would agree that this probably needs some thought. Mostly along the lines of deflections for the tie-down applications. I see that you are currently scaling up the tie-down system deflections based on the free-standing MASH versus 350 deflections. I think that may be too conservative as we don’t expect that kind of jump in deflection for the anchored barriers.

 

I will try to give this some more thought and come up with some numbers. I believe that TTI has some MASH testing of tie-down barriers from with similar 350 testing that could be looked at.

Date May 12, 2015


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