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Buttress Shape for NE Transition

Question
State UT
Description Text

My question is in reference to TRP-03-210-10 report and the
adapted Nebraska transition.  For reference I have attached the Nebraska
Std. Dwg.



 Within the drawing they show the end of the concrete rail
placed at a flare.  My question is, can this transition be used on a
constant slope barrier end with no flare?  Second, as I understand the
report this transition would not be used on New Jersey shape barrier?

Keywords
  • Approach Guardrail Transitions
Other Keywords concrete end parapet buttress
Date December 8, 2015
Attachment Nebraska.PDF


Response
Response

We recommend utilizing the same concrete buttress geometry as the tested and approved system.  We do not recommend altering the concrete barrier design adjacent to the transition region as geometric changes can lead to vehicle snagging and/or instabilities.  Numerous full-scale crash tests has shown that altering the geometric shape of the buttress can be the difference between passing and failing a crash test.  Therefore, the taper/flare of the front edge of the concrete buttress should remain in place to prevent vehicle snag issues.  Also, the buttress shape should remain as a vertical faced barrier in the transition region.

 

That being said, you could utilize a shape transition between the vertical faced buttress and a New Jersey shaped bridge rail.  The shape transition could begin just downstream of the thrie beam end shoe and may be completed over a 7-8 ft distance.  Thus, the total length of the concrete rail be get a little longer (due to the shape transition), but you could utilize this approach guardrail transition and buttress in combination with a New Jersey shaped bridge rail.

Date December 8, 2015


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