Join Eric Chappell for an in-depth discussion in this video Working with targets, part of Basic Roadway Design with Civil 3D.
Corridors have the amazing ability to interact with other parts of your drawing. This allows them to change their shape to meet your design needs without having to do a lot of extra work. This is made possible through something called a target. In this video, you'll learn what targets are and how to apply them to your corridors. In this video, we'll look at two examples of targeting, starting with daylighting. If we look at the sub-assembly on the left and right ends of this assembly, we see that these have to do with targeting.
And if I check the Properties window, you'll see that we've got some slopes applied here. Two to one cut slopes and four to one fill slopes, as well as some ditch geometry. Because the way the sub assembly works is wherever it's in fill, it'll just do a straight slope at four to one. And wherever it's in cut, it will actually add a ditch before it finishes out the slope with a two to one slope. So what I need to do is go into my corridor configuration and I need to tell the corridor what target to use for this sub-assembly.
Civil 3D is really smart, but it can't read your mind and guess what objects you'd like to target for these sub-assemblies that have targeting capabilities. So to handle that, I'll click the corridor, and I'll launch the Edit Targets command on the contextual corridor tab. I'll select a region, which in this case is easy because there's only one region that extends from the very beginning to the very end of the corridor. And that brings up my Target Mapping dialogue. And this is the location where I assign a target to a sub-assembly that has targeting capabilities.
Here we see my basic side slope cut ditch sub-assembly, which currently has no targets assigned to it. It's just as easy as clicking the cell, choosing the target and clicking OK. If I had a long list of targets here or potential targets, I could use the click here to set all cell to pick once and have that target assigned to all of the choices beneath. For two of them it's not a big deal. But imagine if you had 10 or 12, the time it would save from having to pick each one.
Notice that right now, those are the only targets I have. And when I click OK, Civil 3D's going to go out and calculate the intersection of that four to one slope with the existing ground surface. And where all of these purplish lines end, those are the points where it calculated that location. Now if I go to an area to the south here, I'll start to see some areas where there is some red. These are areas that are in cut. And you can see the extra lines that were added to define the ditch.
So here in the fill situation, we've got the sidewalk and then we jump right down into a fill slope. But here in a cut situation, we have the sidewalk. We slope down to the bottom of the ditch, across the bottom, back up to the top. And then we finally tie in with a two to one slope. And as I travel down the corridor, you can see there are varying areas of cut and fill, places where I have ditches and places where I don't. All of that was calculated for me by Civil 3D for literally 100 of corridor sections.
Imagine the time that was saved from you having to do that manually. Let's look at another transitioning or targeting application up here at the north end of the road. Here we'd like to create a turn lane, so that traffic traveling through this intersection can do so more smoothly. You may also notice a heavy, yellow polyline. I've drawn this polyline to represent the path of the right edge of the right lane, and here you can see it's following its original position. And then I want it to gradually transition outward until it becomes twice as wide as it originally was.
So it's going to widen from 12 feet to 24 feet and that will add the second lane that I need for a turning lane. So if you recall back when we were in the Target Mapping dialog, there was only one instance where we could apply a target and that was a surface target for the daylighting. Right now, the sub-assembly that we have for the lane does not allow targeting. So we need to swap it out with one that does. To accomplish that, I'll open the tool palettes and find the Basic Lane Transition tool.
I'll click that tool and one of my options is replace. So I'll click Replace, and simply pick one of the lane sub-assemblies. It doesn't appear as though anything happened because the two sub-assemblies are so similar. But we've just replaced that with a sub-assembly that does have targeting capabilities. I'll repeat the command again using the replace option, it's time for the left sub-assembly. Now for this particular example, I really don't need it on both sides. But I'm going to go ahead and swap it out on both sides, just in case I need it elsewhere.
I'll close down these windows because I don't need them any longer. Before I go into the Target Mapping dialogue and assign targets, I need to make one more change. I'll select my sub-assembly and go into the Properties window. And for this particular sub-assembly, I need to choose the transition method. Right now, it's set to hold offset and elevation, which kind of locks it down and doesn't let it transition at all. Instead I want to use the option of hold grade change offset. What that means is currently that lane is drawn at a 2% cross-grade.
As it widens out, I want it to hold that grade and change its offset. So it will maintain a two percent grade as it widens outward. And I need to do that for both the right and the left side. Hold grade. Change offset. Now I'm ready to assign targets to my corridor. I'll click the corridor. Click Edit Targets. Select a region which again, there is only one. And now we see the additional targets available because of that change we made. And actually with this particular sub assembly, you can transition in the horizontal with, with our offset targets or in the vertical with slope or elevation targets.
For this video, we're only interested in the horizontal transition. So for my right lane, I'll click where it currently says, none. Tell it that I want my type to be feature line, survey figure or polyline. Because I happen to have a polyline in the drawing. I'll pick Select from Drawing and then simply go out and pick the yellow polyline. Press Enter and Civil 3D registers that polyline as Polyline 1. And that's really all there is to it.
I'll click OK. OK again. And the corridor will widen out to create the turn lane, just as I'd hoped it would. So here you can see how it follows that transition from 12 feet out to 24 feet. So as you've learned, targets are applied to allow your corridor to interact with other parts of your drawing. This allows you to make design changes quickly over a large area. Now that you know how targets work,, you can begin assigning them to your own road designs.
- Establishing the road centerline using an alignment
- Capturing and defining road elevations with profiles
- Designing the road cross-section using an assembly
- Building a 3D model of the road using a corridor
- Creating sections views of your design
- Designing intersections