Civil 3D - Fixed Spiral between fixed tangent and fixed curve

[Spirals]

Hi there,

I'm trying to recreate an existing alignment using Civil 3d 2012, however I can't get the right spiral.

The sequence is tangent + spiral+ curve. They are all fixed and I have the points where the spiral starts and ends.

Thanks.

[Alfred.NESWADBA]

Hi,

>> They are all fixed and I have the points where the spiral starts and ends

All fixed might result in curves with none tangential break points.

What are the values you have and maybe a drawing-upload for us to see what you got/what you tried ... might help

- alfred -

[Spirals]

Hello Alfred,

As you mention, indeed the spirals I get are not tangent so I wonder if it
can be done in a different way.

Attached a jpg of my geometry.

Thanking you.

S.

[Alfred.NESWADBA · Accepted solution]

Hi,

>> indeed the spirals I get are not tangent so I wonder if it
>> can be done in a different way.

No, if the current specifications are that hard/that exact with start-point, end-point, radius/K/... values then I guess the specs are wrong.

If you have the chance for using some tolerances then you might use other construction types like floating curves/spirals to come as close as possible to the specs.

- alfred -