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Vertical Curve Question


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#1 Callan74

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Posted 19 October 2011 - 05:56 PM

Hey I have a quick question about vertical clearance on a vertical curve. When looking for vertical clearance on a curve do the equations change based on the location of the structure when compared to the PVI? Do I use one set of equations if the structure is before the PVI and another set if the structure after the PVI?

The basis of the question is from NCEES 2000 example 511 (question pg 105 and solution on pg 192) and the Goswami all in one example on page 694.

I am trying to get a better handle on vertical curves, I feel pretty good with horizontal curves and working on my weak points.

thanks,

C

#2 civilized_naah

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Posted 19 October 2011 - 06:23 PM

You can use equation 404.24 and fig 404.9 for both cases.
just remember to use the correct sign for h and v
if point on curve is to the left of PVI, h is negative
if point on curve is to the right of PVI, h is positive
if point on curve is below the PVI, v is negative
if point on curve is above the PVI, v is positive

#3 Ambrug20

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Posted 24 October 2011 - 12:18 AM

to figure the elevation of obstruct object or clearance, no need to use different formulas. It all the same. Just make sure, than when you calculate K=G_2-G_1/L, it could have negative value. But the rest of the calculations should be the same

#4 Callan74

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Posted 24 October 2011 - 02:44 PM

Thanks for the replies. Off to go study some more.

C




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