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Question
State	KS
Description Text	What is the Zone of Intrusion (ZOI) for TL-5 barriers?

System Performance Evaluation

System Types
Bridge Rails
Permanent Concrete Barriers

Applications

System Features

Date March 12, 2014
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Response
Response (active)	The following were the ZOI measurements from the TL-5 bridge rail and the TL-5 median barrier tests conducted at MwRSF between 2004 and 2007. The critical ZOI value was found to be 76.5" - measured from the median barrier crash test. Bridge Rail - Working width = 79.5" Top corner offset from front of barrier = 5.5" ZOI = 74" Median Barrier - Working Width = 86.5" Top corner offset = 2" (lower slope)+ 8" (head offset) = 10" ZOI = 76.5" The ZOI values were calculated from the working widths (measured from high speed video) and the offset distance between the top-front corner of the barrier and the front of the barrier. Both of these barriers incorporated a head slap prevention geometry, so the top of the barrier was offset above 35" in height. If you wanted to apply these ZOI numbers to a vertical parapet, conservatively you could add back in the offset distances noted above to yield an 86.5" ZOI.

Response

Response
(active)

The following were the ZOI measurements from the TL-5 bridge rail and the TL-5 median barrier tests conducted at MwRSF between 2004 and 2007. The critical ZOI value was found to be 76.5" - measured from the median barrier crash test.

Bridge Rail - Working width = 79.5"

Top corner offset from front of barrier = 5.5"

ZOI = 74"

Median Barrier - Working Width = 86.5"

Top corner offset = 2" (lower slope)+ 8" (head offset) = 10"

ZOI = 76.5"

The ZOI values were calculated from the working widths (measured from high speed video) and the offset distance between the top-front corner of the barrier and the front of the barrier. Both of these barriers incorporated a head slap prevention geometry, so the top of the barrier was offset above 35" in height. If you wanted to apply these ZOI numbers to a vertical parapet, conservatively you could add back in the offset distances noted above to yield an 86.5" ZOI.

Date March 12, 2014
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Response
Response (active)	We have an update based on recent testing for 50" tall TL-5 barriers. TTI recently tested a 50" tall TL-5 barrier for Penn DOT. The bridge rail was a vertical combination rail with a height of 50". The working width for this test was 51.9". This would correlate to a ZOI of 51.9 inches as well for a vertical barrier. Thus, you may want to consider ZOI values as high a 52" for 50" tall, TL-5, vertical bridge rails and parapets. We hopefully will be able to consolidate this guidance in NCHRP 22-34. Thanks

Response

Response
(active)

We have an update based on recent testing for 50" tall TL-5 barriers.

TTI recently tested a 50" tall TL-5 barrier for Penn DOT. The bridge rail was a vertical combination rail with a height of 50". The working width for this test was 51.9". This would correlate to a ZOI of 51.9 inches as well for a vertical barrier.

Thus, you may want to consider ZOI values as high a 52" for 50" tall, TL-5, vertical bridge rails and parapets. We hopefully will be able to consolidate this guidance in NCHRP 22-34.

Thanks

Date October 3, 2019
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Attachment PennDOT PA 5-12 Summary of Results.pdf

ZOI for TL-5 barriers