Creating Intersections in Civil 3D: Step-by-Step Guide

In this video, we're gonna go ahead and create some intersections now that we've prepared our corridors to accept them. So to do that, we're gonna go ahead and drop down into this intersections dropdown, select create intersections, and then Civil 3D is going to prompt us to select our intersection point.

I'm gonna go ahead and start by creating the first intersection, which is gonna be our highway and our dev main alignment. So I'm gonna go ahead and zoom in to around where our intersection is. I'm gonna go ahead and hover over where that intersection might be, and I'm gonna try and snap using this X snap right here for intersection.

I'm gonna click. Now, sometimes Civil 3D doesn't quite grab the right one. So I'm gonna click around in here and try and find that intersection.

And so I've now clicked around. Civil 3D did find the intersection. So I had to click a little bit up above here, but ultimately Civil 3D did find this intersection.

Sometimes it has a little bit of a hard time. But moving on from here, I'm gonna go ahead and write in the name for my intersection, which will be intersection highway-dev. And then I'm not gonna write it into description.

Learn Civil 3D

• Nationally accredited
• Create your own portfolio
• Free student software
• Learn at your convenience
• Authorized Autodesk training center

Learn More

I'm gonna leave my intersection marker as the marker style for this. I'm gonna leave the layer the same as what Civil 3D has preselected. I'm also going to save this as a basic intersection label style.

We can add labels or change the label styles later. Same thing with this marker style. We can modify that marker style if we need to.

Now, what we need to do is decide how we're gonna be handling the intersection corridor type. When you choose this, Civil 3D will automatically update this little image down here. So you're either gonna do all crowns maintained, which is like a standard intersection, or you're gonna go ahead and do a primary road crown maintained.

Now, for this intersection, I wanna go ahead and do primary road crown maintained because we are doing an intersection with a highway where we don't wanna mess with the cross slopes of the highway, and then we have a secondary road coming in. When we do our dev branch to dev main alignment intersection, we'll do the all crowns maintained. So I'm gonna go ahead and select primary road crown maintained.

I'm gonna go ahead and click next. So inside of here, what we're seeing here is priority one, existing highway, priority two, dev main. It's giving us station equations for the intersections.

It's giving us the profiles associated with those alignments. So from here, we're gonna go ahead and look at our offset parameters for our alignments. So I'm gonna go ahead and go in here and choose offset parameters.

So as we can see here, we're doing primary road offset parameters and secondary road offset parameters. So what I'm gonna go ahead and do is I'm going to look at this and say left offset alignment definitions. I'm gonna change my offset value to zero because on the left-hand side, we're not modifying the roadway.

So I don't wanna include any information on the left-hand side. Then we have the right-hand side. So on the right-hand side, we know that the road is 30 feet wide.

So I'm gonna go ahead and type in 30 for the offset value. And then we'll do some modifications to the intersection after Civil 3D creates that intersection. So I'm gonna go ahead and click okay for that.

I'm gonna go to my offset values for my secondary road. And I know that the offset values for that are 17 because that's the lane widths that we selected when we created our original assemblies. So then I'm gonna go ahead and click okay.

So moving on from here, I'm gonna go to the curb return parameters. When you have selected an intersection, we're not doing information on the left-hand side and our alignment doesn't cross through. So Civil 3D knows that we only have two curb returns that we're gonna be creating, the southeast quadrant and the southwest quadrant.

So I'm gonna go ahead and go with the southeast quadrant first. And then it's giving us an option to do a widened turn lane for incoming road or a widened turn lane for outgoing road. We've already created this widening so we don't need to check these to create them.

So what we're gonna go ahead and do is we're going to choose the curb return type and the radius. I'm okay with a circular fillet, but I wanna change my radius to 10 feet. So I'm gonna go ahead and highlight 25, change it to 10.

Civil 3D is not letting me change it to 10. I'm gonna try it one more time, 10, there we go. Now I'm gonna go ahead and go to my southwest quadrant, do the same thing, change 25 to 10.

And then I'm gonna go ahead and click okay. So moving on from there, we have our lane slope parameters and our curb return profile parameters. I don't need to change these or modify them.

Civil 3D is going to create these for me utilizing what's in these profiles here. And since you can see the defaults are all 2%, I'm okay with that because all of my assemblies that I created were at 2%. So I don't need to modify that.

And then I don't wanna modify anything related to the curb return profiles. I don't have any profiles I wanna target. So I'm gonna go ahead and leave this information as is.

But if you wanted to change it, you have your southeast and southwest quadrant information that you can change. I'm gonna go ahead and click okay. And then I am going to move on to the next section, which is the corridor regions.

I'm gonna go ahead and click next. And then inside of here, you have the options for create corridors in the intersection area. Yes, we wanna do that.

We wanna create them as new corridors. We don't wanna add them to an existing corridor. We want to select a surface to daylight to, which is the CIV202.