This article provides an in-depth tutorial on how to add curves to an alignment in Civil 3D. The article delves into the options for fixed, floating, and free curves, and the processes for implementing these types of curves into the alignment.
Key Insights
- The alignment layout toolbar in Civil 3D provides options for adding fixed, floating, and free curves to a drawing. Each type of curve is fixed to something, with fixed curves generally attached to two or more points, floating curves tied to an entity and a point, and free curves offering a more flexible approach.
- The article explains the different options for each type of curve. For instance, fixed curves offer choices like 'fixed curve three points', 'fixed curve best fit', and other options. Floating curves include options like 'floating curve from entity', and 'floating curve best fit'. Free curve fillet is commonly used, especially when adding curves between two entities.
- The tutorial also demonstrates how to add a free curve fillet between two entities with a specific radius. This process includes selecting the entities, specifying the curve solution angle, and defining the radius. Once the curve is added, Civil 3D provides information about tangency and adds labels indicating where the curve begins and ends.
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So in this video, what we're going to go ahead and do is we're going to add some curves to that alignment that we just created. If you, like I did, closed your alignment creation toolbar, we can go ahead and open that alignment creation toolbar and start editing this alignment.
By selecting the alignment, the contextual ribbon bar will pop up in the top and then we're going to go ahead and select geometry editor. When you select geometry editor, the alignment layout toolbar comes back up. And so we're going to be dealing with adding curves.
So inside of this dropdown for curves, you have three different kinds of curves that you can add to a drawing. Now, just as we have three different kinds of curves, there are three different kinds of lines. We're not going to add any lines into our drawing, but all of the ideas and topics we're going to cover related to curves also relate to lines.
So inside of curves, the three types we have are fixed, floating, and free. And so generally, the curves are actually fixed on all of these cases. It's just what are they fixed to.
So a fixed curve is generally related to being fixed to two points or more. So in our options here, we have fixed curve three points. So you can pick three points that your curve would be fixed to.
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Then you have more fixed curve options. So you have two points in a direction, two points in a radius, center point, and through point, and all of these other options that you have over here. Then you have your options of doing a fixed curve best fit and choosing points associated and then fitting a curve through those points as best you can.
Then you have the options for floating curves. Now, floating curves are generally tied to an entity and then tied to a point. So an entity being a tangent or another curve.
We have the options of floating curve from entity, given a radius, and through a point. Then we have more floating curve options. We have from an entity through a point, from an entity end, given a radius and a length, from an entity through a point, and then a direction at that point.
So depending on how you want to create a curve, any of these options could be viable for you. You also have a floating curve best fit, where you would pick an entity and then pick some points. So moving on from there, we have our free curve fillet.
And so these are the options that I find myself using in most of the time when I'm doing workflow for creating alignments and I've only created tangents and I want to add curves in is I'm doing these free curve fillets between two entities and radius is the one that I use most often. And then secondary to that would be through point. If I know a point, but I don't know the radius that I want to hit, then I would go ahead and use this one.
So in our case, we're going to go ahead and do a free curve fillet. Now you do have the option for free curve best fit if you have multiple points rather than just a single through point and you want to try and fit it best with those points and being tied to two entities. So what we're going to go ahead and do now though is do a between two entities with a radius.
So I've selected between two entities with a radius and Civil 3D is going to ask me to select my first entity. So I'm going to go ahead and add these curves in starting from my first tangent going to my second, then my second tangent going to my third. So I'm going to go ahead and select my first tangent.
Now it's telling me to select my next entity. I'm going to go ahead and select my second tangent. And now Civil 3D is going to ask me if my curve solution angle is greater than 180 or less than 180.
If I want my curve to come on the inside of this, then I know that my curve solution angle is less than 180. So what I'm going to go ahead and do is choose less than 180. And then I'm going to specify my radius.
I'm going to specify 50 feet. I'm going to hit ENTER. And as you'll see, Civil 3D has now put in this curve.
And now it shows me this information about tangency. We're going to go back up and look at tangency as we described in the first video when we created our alignment from an object in the next video. We're going to go ahead and go and add in our next curve before we end this video.
So I'm going to go ahead and select this entity. I'm going to select my third entity. And then I'm going to again, choose less than 180 because I know that this angle in here is less than 180.
I'm going to go ahead and type in 50. And then I get a curve with a 50-foot radius. And I have my tangency.
And I can go ahead and hit escape to get out of this command. Now that I've hit escape, Civil 3D has added in some new labels. So these new labels are points on the curve and then points that transition.
So these are giving me the stations of where the curve begins, where the curve ends. And then same thing here, where the curve begins, where the curve ends. So what I'm going to go ahead and do now is I'm going to go ahead and save.
And then I'll meet you in the next video.
