Parking lot design is crucial to a successful commercial project. How the parking lot is graded can make or break a project based on the amount of cut-and-fill. It can also have an impact on grading and drainage-related costs. Parking lot designs can be done in many ways within Civil 3D.

In this session, we’ll take a look at feature lines in parking lots. By the end of this tutorial, you’ll be able to:

Use interim grading surfaces to begin your design.
Use Feature Lines to help streamline parking lot grading.

Here’s how:

First, we will do a quick grading on a parking lot in Civil 3D. On the left of our example, there is a corridor with some elevations we know. We want to create an interim grading surface so we’re going to extract a Feature Line from the corridor.

Select the corridor.
Click “Feature Lines from Corridor” from the “Launch Pad” panel.
Select the Feature Line you want and extract them all.
A window titled “Extract Corridor Feature Lines” will appear. Click “Extract”.
In this example, we are going to right-click on the Feature Line and select “Remove Dynamic Link…”
Right-click the Feature Line again and select “Move to Site”.
A window titled “Move to Site” will appear. Create a new site by clicking the “New” button.
Name the new site and click “OK”.
Click “OK” in the “Move to Site” window.
Now that we have our Feature Line, we’re going to create a grading object that goes throughout the parking lot.
In the “Home” tab, select “Grading” and then “Grading Creation Tools”.
A “Grading Creation Tools” window will pop up. Select the “Select Grading Group” icon on the far left.
In the “Select Grading Group” window, ensure the site name matches the parking lot. Select the “New” icon next to “Group name”.
Name the grading group and check the box for “Automatic surface creation”.
Hit “OK” in the “Select Grading Group”, “Create Surface” and “Select Grading Group” (again) windows.
Back in the “Grading Creation Tools” window, grade the surface by selecting the icon and selecting “Create Grading”.
Select the Feature Line and then select “Continue grading without feature line weeding” in the window that appears.
Set your grading side and distance. For the distance, we’re going to measure to the outside of the parking lot and set the grade at “-2%”.
The result is a surface that we’re going to use for draping polylines.
We’re going to get rid of this grading object by freezing it.
We’re also going to get rid of this surface by right-clicking on it and selecting “Surface Properties” and changing the “Surface style” to “No Display”. Click “OK”.

To turn items into Feature Lines:

Starting with these three lines, click on “Feature Line” from the ribbon and then “Create Feature Lines from Objects”.
Select the three lines and hit “Enter”.
A “Create Feature Lines” window will appear. Ensure the “Site” is the parking lot you’re working on. Check the box for “Style” (leave the style as “Basic Feature Line”) and check the boxes for “Erase existing entities” and “Assign elevations”. Hit “OK”.
A window titled “Assign Elevations” will pop up. In the drop-down menu from “From Surface”, select “Interim Surface”.
Uncheck the box for “Insert intermediate grade break points”. Hit “OK”.
Select your new Feature Line and then click on the quick elevation edit tool. We’ll use this to grade and make changes to slope elevation.
After selecting the tool, check the elevations of your Feature Line by hovering over it.
In our example, we noticed there are parts of our line that are not at the elevation we want. We can adjust the elevation by hovering over the area of the line and keying in the difference we want to take off/add. Hit “Enter” and then “Escape”.
Now we want to add our finish grade to a surface. Begin by clicking on “Feature Line” from the ribbon and then “Create Feature Lines from Objects”.
From there, select the building and curbs and hit “Enter”.
In the “Create Feature Lines” window, uncheck the box for “Erase existing entities”. Make sure the “Assign elevations” box is checked.
In the “Assign Elevations” window, make sure the “Interim Surface” is chosen from the drop-down menu. Click “OK”.

To add Feature Lines to a Surface:

Select all of the lines and click on “Add to Surface as Breakline” in the ribbon or by right-clicking.
A window titled “Select Surface” will appear. Select the “+” sign to create a new surface.
In the “Create Surface” window, name the surface, select the style you want and hit “OK”.
Click “OK” again in the “Select Surface” window.
A window titled “Add Breaklines” will pop up. Check the box for “Distance” and set the distance. For this example, we are setting the distance at “5.00’”. Click “OK”.
In the case that you get something like this, where the elevation is off, select a Feature Line and the quick elevation tool and hover over the elevations.
Our problem here was that there was a “0.00’” elevation on one of our Feature Lines. To remedy this:
Select the incorrect elevation
Specify the elevation by keying in “S” for “Surface” and “S” again to select a surface
A box titled “Select surface” will appear. Select “Entrance road” (or the surface of your corridor) from the drop-down menu.
Hit “OK”.
You’ll see the elevation change to match the surface. Click “Enter”.
Double-check that your surface is set to “Rebuild – Automatic”. If it is not, open your “Toolspace” and right click on your surface and select “Rebuild – Automatic”.

To straight grade a surface, there are two ways:

Insert an elevation point:

Select the “Insert Elevation Point” tool from the top of the screen.
Check the elevations of each end of the area you want to straight grade.
Select the place you want to place the elevation point and key in the elevation somewhere in the middle of the two end points.

Set a slope between two points:

Use the “Set slope between points” tool in the ribbon.
Select the starting point and follow the feature line.
Hit “Enter”.
Hit “Enter” again to accept it.

To turn on Slope Arrows:

Right click on the surface and select “Edit Surface Style”.
Turn on “Slope Arrows” in the Display tab.
This will show you at all times where things are draining to.

Evening the elevation of a building:

By using the “Slope Arrows” tool, we were able to see that our building was not entirely at the same elevation.
Select the feature line of the building.
Click on the “Elevation Editor” tool at the top of the screen.
The elevations of the building will appear in the Panorama. Select all of the elevations in the list and key in the elevation you want.
This will bring your entire building to the same elevation.

To do a Stepped Offset:

In this example, we begin with a curb that we’ve already done the grading and design for the edge of asphalt. Select the “Stepped Offset” icon from the “Edit Geometry” panel.
Key in the distance. In this example, “2’”.
Specify the elevation change on the inside of the edge of asphalt. In this example, “0.33”.
We will also repeat this process to the other curbs in our parking lot and add them to the surface. Select all of the breaklines and right-click and select “Add to Surface as Breakline…”.
*These are not dynamic, so if you change the edge of asphalt, it’s not going to change the back-up curb.
In the “Select Surface” window that will appear, choose your surface and click “OK”.

Now we have a finished ground surface that we can continue to modify. The elements of the ground surface are dynamic which makes the parking lot grading quick and easy.

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