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critical length of grade


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#1 pinkpig

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Posted 16 September 2008 - 04:26 AM

How to calculate a critical length of grade for a vertical curve?

#2 nomind

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Posted 16 September 2008 - 03:45 PM

QUOTE (pinkpig @ Sep 16 2008, 04:26 AM) <{POST_SNAPBACK}>
How to calculate a critical length of grade for a vertical curve?


I found the answer from Green Book Page 240.
Critical Length of Grade derived as tangent grade.
where vertical curve is part of critical Length of grade, an approximate equivalent tangent grade should be used.
Refer to Exhibit 3-69
Vertical curve Type II and IV, the grade algebraic difference is not too great, critical length of grade maybe measured as between VPI.
I would think it is measure btw PVC and PVT

For Vertical Curve Type I and III, one-quarter of vertical curve length is considered as part of critical length of grade.


If anything wrong, please point it out.
Thanks




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