How do I draw a 3-d curve in Civil 3D? I have a curved alignment that has a horizontal curve and is also curved in the vertical direction. I'm not sure how to draw this. Can somebody help me? Thank you
If you're using Alignments, the vertical is defined using a Profile.
You can also use Feature Lines, which are a bit like a "light-weight Alignment", but those cannot have vertical curves. A Feature Line can have a true horizontal curve, but as opposed to a Profile, a Feature Line can only straight-grade from grade break to grade break.
By contrast, a 3D Polyline cannot have curves in either horizontal or vertical directions, and all curves must be approximated using a series of short line segments.
*if* you needed a literal 3D curve, Sinc is right, you would need to approximate it using a series of segments. The best way would be an alignment for the horizontal, profile for vertical, subassembly, corridor with a high frequency, extract a feature line from that.
You can have a 3D curve, but it can't be an alignment/profile combination. For example, you would create a feature line that is curved, you would have different elevations at each end of that curve...there is your 3d curve.
I'm thinking you'll need to run a cooridor, create a surface, then view it in 3d view. You'd be able to see the resulting centerline that way.
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