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ZOI for TL3 Pickup and TL4 SUT

Question
State FL
Description Text

Back in June of 2008 you had some correspondence regarding the ZOI for TL3 pickups impacting taller barriers. At that time you referenced some tests by TTI impacting a 42" vertical wall with resulting ZOI values of 1.4 and 1.7 feet.

 

We are now (finally) taking a look at revising our standards for barrier walls adjacent to bridge piers. What we are proposing is to take a 32" tall safety shaped F barrier with a flat back against the pier(s) and extending it vertically for some amount to reduce (eliminate?) the intrusion of a pickup truck. For comparison, we would also like to consider the TL4 vehicle, but anticipate that we will use the pickup for the final design. (For this application, it is understood that a pier protection barrier is not required; only a barrier to protect the vehicle occupants.)

Keywords
  • Permanent Concrete Barriers
Other Keywords none
Date February 4, 2010


Response
Response

I went back to look at the old correspondence and copied it below. Unfortunately, I cannot remember which tests, barrier shapes, and heights were reviewed. For this, I must apologize. I have also copied some very brief guidance that we provided to the Wisconsin DOT for a single slope concrete barrier. It is contained below.

 

For the Florida situation, are you seeking the ZOI value for a tall 42-in., F-shape concrete barrier under TL-3 conditions with either the 2000P or 2270P pickup truck vehicles?

 

Old correspondence with WisDOT:

 

Here are my suggestions (TL-3 " single slope):

SS Barrier Height        WW                             ZOI

32"                               27                                21

36"                               27 (assumed)               ?? (measured from top front corner but unknown)

42" (<)                         27 (assumed)               ?? (measured from top front corner but unknown)

42" (>)                         24 (barrier width)        0

51"                              24 (barrier width)        0

56"                              24 (barrier width)        0

 

Vertical Barrier Height

32"                              24                               24 (vertical barrier has toe and front corner at same position)

 

Below is some past correspondence with FLDOT.  The inquiry is in blue.  My responses are in red.

 

Can you please give me your best estimate of a TL-3 ZOI for:

 

 1)      A 42" F Shape barrier

 

 2)      A 32" F Shape barrier that has a vertical extension on its

 top that increases its total height to 6'-0".

 

 

 My intuition is that the TL-3 ZOI should decrease somewhat from the

 1'-6" value shown on Page 18 of your Guidelines for Attachments to

 Bridge Rails and Median Barriers report.  We've got a tight spot

 where we are trying to squeeze something in next to a barrier so I

 need to ask for your best guess on these ZOI values.

 

For the 42" F-shape, I believe that the ZOI value would be

much reduced within the upper 10" of additional barrier height.

Without reviewing test films, I may estimate this number to be within

the single digits as long as the engine hood does not extend over the

taller barrier. It may be close though. If it extends over the top, we

may still get 15 to 18" of ZOI. I will be better able to evaluate this

when I return home.

 

One of my associates looked up TL-3 pickup truck tests into a 42" tall,

vertical aesthetic barrier that was tested by TTI. For those tests, the ZOI

values were 1.4 and 1.7 ft. My recollection was that the ZOI for vertical

shapes was higher than for safety shapes. As such, the same scaling could be

used to estimate the ZOI for 42" safety shape barriers.

 

 

The estimated ZOI for the 6' barrier would be 0".

 

 

 

 

Date February 4, 2010


Response
Response

We really appreciate all of your assistance! What we currently need is the Zone of Intrusion for a 42 and 54 inch F-shape barrier from both a pickup truck and an SU truck.

Date February 11, 2010


Response
Response

We have reviewed several research reports on the crash testing of rigid concrete parapets with various front-face geometries. Unfortunately, we have been unable to find sufficient test data or information in existing reports that can definitively guide us in determining the ZOI for 42 and 54-in. tall F- and NJ-shape parapets under impacts with both TL-3/TL-4 pickup trucks and TL-4 single-unit trucks. Using prior guidance, engineering judgement, and a limited review of test reports, we are approximating the ZOI for pickup trucks to be 0 in. for both 42 and 54 in. parapets. For TL-4 single-unit truck impacts, the ZOI is estimated to be 24 and 12 in. for 42 and 54-in. parapets, respectively.


Please note that this information is very rough due to the unavailability of crash test data corresponding to your noted conditions. If you have additional questions or comments, please feel free to contact me at your earliest convenience.

Date March 5, 2010


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