This article walks you through the process of creating a surface or grading object from feature lines, detailing steps such as placing lines as an approximation of daylight lines and drawing a polyline. Designed for learners with some knowledge of Civil 3D, the article breaks down each step so you can easily follow along and apply these steps to your own projects.
Key Insights
- The process of creating a surface or grading object from feature lines includes drawing a polyline, selecting midpoint, and creating feature lines from objects. It's important to specify your site during this process.
- Creating daylight lines on both the street side and the backside is important. Assigning names to the feature lines can help with organization and further steps in the process.
- The article also highlights how to create a stepped offset from a line using Civil 3D. It's crucial to specify the offset distance and the offset side, as well as set the elevations from surface where necessary.
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We've got two more things we need to do before we're about ready to create a surface or grading object from these feature lines. So what we're going to go ahead and do now is we're going to be placing some lines down that are going to be used as an approximation of our daylight lines.
So what I'm going to go ahead and do is I'm going to draw a polyline. I'm going to start somewhere in the middle of this Parcel boundary right here. So I'm going to shift right click.
I'm going to choose Midpoint. I'm going to click on this. I'm going to pick this corner here.
I'm going to go along the right-of-way line here. So I'm going to pick this point here. I'm going to change to an arc.
I'm going to pick this point here. I'm going to switch to a line. I'm going to pick this point here.
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I'm going to switch to an arc. I'm going to pick this point here. I'm going to stay as an arc, and I'm going to pick this point here.
I'm going to go ahead and hit ENTER to get out of that polyline command. And then from here, I'm going to go ahead and Create Feature Line from Objects. I'm going to select from objects.
I'm going to select this polyline. I'm going to hit ENTER. Civil 3D is going to ask me to specify my site.
I'm still going to be on Dev Branch. I'm going to go ahead and call this Daylight Street. I'm going to leave it as Grading Design.
I'm going to leave it as C Topo Feet. I'm going to erase existing entity. I am not going to assign elevations, and I'm going to go ahead and click okay.
So Civil 3D has now created this feature line, which is going to be my daylight line on the street side. Now I need to create a feature line that's going to be my daylight line on the back side. So one thing that didn't happen when we created this stepped offset was that we got a choice for what the name is on this feature line.
So I'm going to go ahead and right click and select properties and look at what the name for this is. And so as you can see here, there is no name for this. So I'm going to type Rear Wall Offset and hit ENTER and then close this.
And we're going to create another stepped offset from this line. So I'm going to go ahead and go to my Feature Line. I'm going to go ahead and Create Feature Line from Stepped Offset.
I'm going to go ahead and specify an offset distance. Now this is going to be where my retaining wall daylights into the grade below. So it's going to be the Catch point for my retaining wall.
So I don't want it to be very far off. It should be vertical, but Civil 3D doesn't do a good job of approximating vertical lines when we're creating surfaces. So I'm going to offset at something like 0.05 and hit ENTER.
So then Civil 3D is going to ask me to select an object to offset. I'm going to pick this line here. Civil 3D is going to ask me to specify an offset side.
I'm going to pick out here and then it's going to ask me to specify an elevation difference or grade. So again, grade would be Percent Grade. If you wanted negative two, you would type negative two for a negative 2% grade or slope, or you would change, you would set it as two or negative two as in a two or negative two to one slope.
Whenever you're doing slope, it's always an X to one type slope. And then elevation, you would specify a specific elevation or variable. Since I'm going to go ahead and drape this feature line onto a surface, I'm not as concerned.
I'm going to go ahead and type E for elevation, and I'm going to specify an elevation of zero. So that when we create this, it is not showing up as being even close if we haven't effectively set the elevations of this. So my value says must be nonzero.
So I'll set it as one. So I'm going to go ahead and hit escape. Now, if I look at this feature line here, and I go to my Elevation Editor, you're going to see all of my actual elevations are one.
So that feature line is well below my surface. So I'm going to go ahead and do two edits. I'm going to grab that last feature line here.
I'm going to go to an elevation edit. I'm going to go to this point here, elevations from surface. I'm going to go ahead and select it.
What Civil 3D is going to ask me to do is it's asking me to set elevations from surface, which surface would I like to pick the elevations from? I want to use my Civ 203 surface, which is my existing surface. I'm going to insert intermediate grade break points. So anytime that feature line crosses a tin line, it's going to add additional elevation points. And then I am going to click OK.
So Civil 3D is now going to ask me to select the object, I'm going to go ahead and select my feature line, you're going to see some of the points that are going to get placed. Now I'm going to hit ENTER to accept it and hit escape. Now when I select this feature line, and I go to Elevation Editor, you're going to notice that all of these elevations are different.
And that's because they have picked up their elevations based on the surface. So I'm going to do the same thing to this feature line, I'm going to pick this feature line, I'm going to select the option of elevations from surface, I'm going to select Civ 203, I'm going to select insert intermediate grade break points, I'm going to click OK. And then from here, Civil 3D is asking me to select the object, I'm going to select the feature line, you're going to see the points that are going to get added in, I'm going to go ahead and hit ENTER to accept it and escape to get out of that command.
And if I select this feature line and go to Elevation Editor, you'll notice again, I have all of the different elevations based on the surface itself. So I'm going to go ahead and hit escape, zoom out. I'm going to go ahead and save this drawing. And then I'm going to go ahead and meet you in the next video.
