Join Josh Modglin for an in-depth discussion in this video Intersection objects, part of AutoCAD Civil 3D Essential Training.
- [Instructor] What we just did in our last exercise, with cul de sacs, is how we really deal with intersections as well, when we're dealing with curb returns and any of those locations, we're going to create an alignment, a profile, a feature line, something like that, that linear path, and then target back to our alignments. Now that's a lot of work, wouldn't it be great if it was automated? Let's look at how Civil 3D has automated the process that we just did in the cul de sac, design exercise for Intersections.
So it's not automated for cul de sacs, and not perfect for every type of intersection, but three way and four way type intersections, we can use an intersection object. And that's what we're going to do, in the Home Ribbon, Create, Design Panel, you have a few different controls under the Intersection, including roundabouts, some really powerful horizontal control design for roundabouts. But we're going to focus here on Create Intersections, to create an intersection, it says select the intersection point, we're going to select where those two alignments come together.
It is going to go ahead and place a Civil 3D intersection style there, we're not going to place a label, put on the right layer, all of these of course, coming from our Settings. There's two different ways to create an intersection object, what we're ultimately doing is, we're linking the horizontal and vertical of these two alignments and profiles, that come together at this intersection. Now if you link the primary with the secondary, how do you want to deal with secondary? Do you want all the roads' crowns maintained? Which may mean, the roads flatten out a bit, where they intersect, but it also means it would only place one new PVI, a linked PVI, at that location.
If you say, primary road crown maintained, notice the three dots here, they represent how many PVIs are going to be controlled for the secondary profile, it's going to be locked and changed dynamically, based up the primary profile and its elevations. So if you want additional PVIs, and making sure you have the 2%, then you do primary road crown maintained. We're going to do all crowns maintained in this exercise.
I'm going to go ahead and click Next, and notice here, it provides us the intersecting alignments. And it immediately knows that if there's a layout type profile, it's going to select that as the option. But it does allow you to change the profile that you're going to link between these alignments. Omega Way is going to be the primary, and that's this one, coming this direction. Because this is a T intersection, the through alignment must be the primary.
Whereas the one that intersects at that location, must be secondary, now if this was a four way intersection, and then you'd have these arrows that are currently grayed out, allowing you to choose which alignment is going to control, which one's priority, which one's secondary. You know what, before I continue though, notice everything else is optional, I can uncheck all of these other options here, and everything else is optional. I use intersections often, just to link profiles, so that as I'm designing, I know that the start of one profile and the cross of the other profile, when one profile moves, all of them are linked together through these intersection objects.
Of course, we're going to continue, we're going to see all the features here of the intersection object. The offset and curb return features really deal with the horizontal, so our offset parameters, control the land widths here. And so our primary road, left lane is 12 feet wide, our secondary, or our primary road right lane is 12 feet wide. We could change these, or we can even link the alignments, or the offsets to alignments.
Because the primary road could have a different offset distances than the secondary, then we have to repeat and confirm these here as well. That provides the horizontal, what about the actual radius and curb return values here? So it provides us this little view, and not only in the parameters window, but we also have some glyphs or previews of which quadrant that we're working in. So in this quadrant, we're going to choose to use a circular fillet, instead of a chamfer or a three centered arc, and use a radius of 25.
Now if we make any changes here, don't forget, we've only changed this quadrant to the corner, this direction, make sure you hit the Next, to set all the values correctly. So that handles the horizontal controls, that really will create a bunch of different offset alignments that are linked. This provides vertical control, and so we're going to have the ability to have lane slope parameters, and the lane slope parameters means that we need to set the slopes for the left and the right, primary and the secondary.
What this does is, the software simply says, give me the distance, give me the slope, and I will dynamically link profiles to the center line profile, and when the center line profile adjusts, these dynamically linked profiles will adjust as well, based on these parameters. Really powerful. So we have those set, and then curb returns, same scenario, of course, it'll take those slopes at that location, and just create a profile that is linked for those slopes.
So the curb return profile parameters here, they're really more connected to the idea of how we're dealing with that transition. So right here is our point of curvature, one of the two, and what we're going to be dealing with, is you have a slope along this road here, say, it's 5% coming down. And you have an 8% road here, and so what you might run into is, this curb return is getting into 15%, going from this slope of the road, to this slope of the road.
And so some jurisdictions set the criteria that to flatten that curb return out more, you're going to extend along the edge of your lane, the flattening, in other words, the lane slope may flatten out from 2% to zero, almost kind of like a super elevation scenario, so as to better deal the the curb return. And because most of the jurisdictions that I've ever worked with, don't require that, I've changed my command settings to say no, do not extend along the profile, incoming and outgoing.
I don't want to change my lane slope, I want my curb return profiles and slopes to be whatever they are, if there's an issue with that slope, if it's too great, I need to go back to my baseline profile design, and review it. But you can extend it, and you can choose long, or how far to extend it in those lanes. Now realize what we've just done, is if we've made the change, we've only made it to this quadrant. We're going to change that quadrant, that means incoming, outgoing, and the distance in both directions.
So that sets all of the controls, we mentioned for a corridor, you need a linear path, here's your linear path. You also need assemblies, on the next wizard, we're going to add this to an existing corridor, our Osceola Road corridor, any assemblies or sub-assemblies that have daylight controls, we're going to daylight to EG. And then we literally have to walk through each assembly to add. Now we've added these assemblies already to the drawing, the nice thing is though, it gives a nice, good look at where it potentially where we'll use those assemblies, and what the assembly may look like, that visual gives us a good control.
So that one, we've seen before, that's lane left, curve right, that one we've built, that was the main road. And some of these I built for you already, and so we'll just walk through setting these together. Now this takes a lot of time to set all of these ones for the primary and then we have to through the secondary, wouldn't it be nice if it just remembered these settings, and we just pick the right saved set? Well that's available right above where we set all these different values.
You can create an assembly set, save all these different values, and then simply browse to that saved set, so you don't have to do this again. So I encourage a lot of companies, especially when they work in jurisdictions a lot, if you work in the same county or city, you set all and create your assemblies for that, and then save them as a set, and you're ready to go. When we've done all the work, let's go ahead and create an intersection, and we see the intersection object created for us. Now again, this is not a separate corridor, it's all part of one, so what we really need to do is, pull all of this back together.
I created separate regions along this road, and shrunk the regions for this one, and just so I had enough space to put that intersection object in, and now I have to pull it all together. Now I could use the diamond grips, we know what they are by now, and we can slide the region end station, or start station, along the path of the baseline. What I found though, graphically is, it's just not very easy to use those grips. So we're going to go to the Corridor Properties, and we're going to find the region in this very big list.
That's too hard. What if we graphically could find the right region? So I'm going to select the region from the drawing, and I'm going to go ahead and pick this region. Now notice the alignment stationing, 7+00, and 7+60, when is select this region, and notice the blue graphic that shows this region's end and edge, and it shows it gray in the Corridor Properties. So what we're changing is the end station of that region. Now instead of typing something in, I'm going to pick, graphically, using my object snaps, on the end of this assembly, or this edge here for this region.
So it'll pull it all together. And we're going to repeat the process for the through road as well. So again, look at the stationing, you have 5+00 and 4+00, so what we're doing is, we're extending the end station of this region, select it, pick the end station, graphically pick it, and I know I'm going to be changing the start station of the next one. You notice how much difference in station there is, horizontal distance, let's hit the start station here.
And pan over, and I'm changing this region here, and changing the start station to line up there. I have all the settings, so I hit OK, it's going to rebuild the corridor, and notice it pulls it all together, and so it acts as one corridor object, contours and everything come together cleanly, as it wraps around the curb return. And the nice thing is, this whole section here is dynamic, I change the profiles or any settings here, that impact this intersection, all of the intersection objects, and the connections of all those intersection objects will come together.
Very powerful means to automate what we really did manually in the last exercise.
This course gets you up and running with AutoCAD Civil 3D. First, instructor Josh Modglin shows how to model a surface, lay out parcels, and design geometry, including the making of horizontal alignments and vertical profiles. Next, Josh demonstrates how to create corridors, cross sections, pipe networks, and pressure networks. Then, he covers working with feature lines and grading objects, and how to share your data. He wraps up by providing an overview of plan production tools.
- Navigating the Civil 3D interface
- Using point groups and description keys
- Importing survey data
- Managing figures
- Creating and analyzing surfaces
- Creating parcels
- Working with alignments
- Working with profiles and profile views
- Working with assemblies and subassemblies
- Creating Basic and Advanced Corridors
- Using an Intersection Object
- Making sample lines, cross sections, and section views
- Creating a pipe network
- Understanding pressure parts
- Creating and editing feature lines
- Creating and editing grading objects
- Sharing and referencing data
Skill Level Beginner
Some of the exercise files do not properly function.
This course was built to work with the latest release of AutoCAD Civil 3D. If you are not running AutoCAD Civil 3D 2018 there are some exercise files that will not work for you.