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About defining profile vertcal radius formula

6 REPLIES 6
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Message 1 of 7
bpoleuca
434 Views, 6 Replies

About defining profile vertcal radius formula

Hello,

can I define my personal formula to make the vertical curve in profile design how I want?

6 REPLIES 6
Message 2 of 7
sboon
in reply to: bpoleuca

Not sure that I understand what you're asking.  Do you want to define your own design criteria, or do you want to create something that is neither a parabolic or a circular vertical curve?

Steve
Expert Elite Alumnus
Message 3 of 7
bpoleuca
in reply to: sboon

Hello,

I don't know how to explaine better.

My civil 3d 2013 is making the vertical curve profile with these formules:

1) External secant => T=(m*R)/200

2) External secant => B=(T*T)/2*R

3) Profile curve lenght => C=2*T

 ----- m = |d1 - d2| %

In some spacial case I need these formules different like this:

1) External secant => T=(m*R)/100

2) External secant => B=(T*T)/6*R

3) Profile curve lenght => C=2*T

 

My vertical curve must be parabolic in the second case and circular curve in the first case.

In this moment, the parabolic curve that is defined in civil 3d is making the curve with the first formules and I need to make the parabolic curve with the second formules.

How can I make these changes?

I hoe you understand my question.

Message 4 of 7
bpoleuca
in reply to: bpoleuca

Nobody know if it's possible to change the vertical curve formula?

Message 5 of 7
sboon
in reply to: bpoleuca

You're going to have to provide more information.  Definitions of the variables that you're using at a minimum, and a picture or dwg to show what you are trying to do here.

Steve
Expert Elite Alumnus
Message 6 of 7
bpoleuca
in reply to: bpoleuca

Hello,

I don't know how to explaine better, but I will try.

 

The way of Civil 3d is making the vertical curve profile I don't know, but these formules are in Romania and they have exactly the same result:

1) External secant => T=(m*R)/200  (R = radius of the vertical curve)

2) External secant => B=(T*T)/2*R

3) Profile curve lenght => C=2*T

4) Grade Change = m = |d1 -/+ d2| %

 

In a special case, I need these formules different .... like this:

5) External secant => T=(m*R)/100

6) External secant => B=(T*T)/6*R

7) Profile curve lenght => C=2*T

 

What I need is to define another way of creating vertical profile curve ..... like a parabola, not a simple curve but to respect the formules numbered 5) 6) and 7) ... in the way Civil 3D is doing the job.

Where I find the definition of the vertical curve profile to make another one with these new formules.

It's no matter if I attach a drawing, because is you take any project you have and apply my formules (1-4) , you will see the result is the same.

Thanks.

Message 7 of 7
wfberry
in reply to: bpoleuca

BP:

 

I am not sure why you need your particular formula for a parabolic curve.  I am thinking it must be something other than a road.  Let's face it, Civil 3D has several methods for a vertical curve and their use is only for constructing a highway.  Whether it is a perfect parabola really doesn't matter since we are building a TIMEX version and not a ROLEX one.  If you REALLY have to have your formula, I would suggest you set up the equation in an Excel file and have it calculate the coordinates.  Then you can plot them and move forward.

 

Just my observation and good luck.

 

Bill

 

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