Create roadway alignments

00:00

In this video, we will demonstrate some of the available methods for creating and importing alignments into Civil 3D.

00:10

We have four alignments that we will use as examples.

00:13

For the Eastern alignment, we can lay out the tangent section based on the points of intersection,

00:19

but we also want to include a reverse curve that we can easily edit.

00:24

In the South alignment, we want to import the alignment based on the linework that is drawn using polylines.

00:32

It also contains a reverse curve, but we want to pay attention to the direction that we draw the alignment,

00:37

since that will dictate the direction of the stationing.

00:40

The West alignment is very basic, but we want to include spirals in the curve.

00:46

In this video series, we will also detail the intersection of the end alignment.

00:54

For the North alignment, we want to import an XML file that may be designed by someone else, or possibly in another program.

01:02

So, to begin with, we will lay out the East alignment with the reverse curve.

01:06

We will provide the alignment name and some of the key parameters, such as the stationing, and the design speed as well.

01:13

Now to lay out the reverse curve, we will draw a tangent between the beginning point and the first PI.

01:19

We'll do the same thing for the end section of the alignment, but the first curve we will enter as a floating curve.

01:27

We can select any point on the first tangent.

01:31

We enter the radius, then we select a through point.

01:34

In this case, we can choose any point on our layout line.

01:38

We’ll just choose the nearest.

01:40

The alignment then updates to include that curve.

01:44

Next, we want to add a second curve as a free curve.

01:49

We will select the first curve and the second tangent, then specify that this is a reverse curve.

01:56

Once we add the radius, our alignment is now complete.

01:60

We can modify the geometry by moving the grips.

02:03

We can see that the reverse curve stays true.

02:07

This option gives us much more flexibility if anything on the alignment needs to change or be revised.

02:15

Next, we'll create an alignment from objects.

02:18

When we do this, the alignment will reflect the exact geometry that we have drawn.

02:23

We want to be certain that we have laid out the curves correctly.

02:26

We need to be aware of the direction in which the line was created.

02:31

To be consistent with the other alignments, we'll start at the intersection point and move South.

02:35

Here, we are simply laying out a polyline by drawing points at each PI.

02:42

Then, we'll run the fillet command at each curve and add a reverse curve near the Northern portion of the alignment.

02:52

Now to create the alignment, we need to choose Create Alignment from Objects from the alignment drop-down.

02:59

Initially, we can specify the direction of the stationing, or if we want to reverse the stationing and how it was drawn.

03:05

Here, we can define the design criteria similar to the previous alignment, stationing, design speed, and other items like that.

03:12

Once the alignment from objects is created, there are a few things that we need to consider:

03:17

simple geometry like curves, points or tangents.

03:20

Those can easily be updated using the grips or tools.

03:25

Complex geometry, like compound or reverse curves, are essentially set by the objects.

03:32

Here, if we revise the reverse curve, a warning will display, showing the elements are not collinear.

03:38

In this case, we could redraw the object, or layout the alignment similar to the first method.

03:44

Next, we have a very simple alignment where we would like to add spirals.

03:49

We take the same steps that we did previously to set up the alignment and layout the points.

03:54

Here, we will choose the free spiral curve, spiral function,

03:59

and layout the curve in the standard method where we select the tangents and specify the radius.

04:05

We also need to indicate the spiral length on both sides of the curve.

04:10

Now, there are other ways that we can add spiral curvature.

04:13

It’s something that users can play with to see all the capabilities of that tool.

04:18

Now for the North alignment, we have a simple layout but we want to import the XML file that contains the geometry for the alignment.

04:25

We do this under the Insert tab and choose Land XML.

04:29

One item to note is that Super Elevation is supported for Land XML files.

04:34

Here, we can choose which items we would like to import into our file, so we'll choose all the available elements there.

04:40

Now, once we've imported that, we have the same editing capabilities.

04:44

In viewing the alignment, we'll see that the stationing may need to be updated,

04:48

so we can do this by selecting the alignment and choosing Properties.

04:52

Here, we can change the stationing or other design criteria or even add station equations if we need them.

04:59

The alignment grid view is available for any civil 3D alignment.

05:03

So, when we choose this function, we can see the detailed geometry.

05:06

We also have the ability to revise the alignment.

05:09

This gives us a level of precision to modify the alignment exactly as is required by our design criteria.

05:17

So the last portion of the segment that we'll cover is for offset alignments.

05:21

We would like to create a corridor with an intersection between the South alignment and then this access road here.

05:28

The Northbound portion of the road will have a turn lane, but that turn lane crosses the center line alignment.

05:36

The same is true for the Southbound approach of the intersection.

05:40

The lane overlaps the alignment.

05:42

So, in order to create a corridor, we will need an offset alignment for the Northbound and Southbound lanes

05:48

that can govern the assemblies.

05:51

In order to do this, we go to the Alignment menu and choose Create Alignment Offset.

05:56

We'll base this on the center line.

05:59

We need to provide some details about the offset alignment.

06:02

So, we'll create the Northbound alignment first.

06:04

One thing we need to consider again is the direction of our stationing.

06:08

The stationing goes from North to South.

06:10

The Northbound is actually on the left side of the alignment.

06:14

So, we'll recreate only the Northbound alignment for now.

06:17

We’ll need to zero out the Southbound side, then set the properties.

06:21

We won't set the labels right now.

06:23

If we have a profile for the center line, we can base the offset alignment profile on that center line, then provide an offset slope.

06:34

The offset was created, but we're showing the line only, no labels.

06:38

We can change the alignment definition, if needed.

06:41

In our tool space, we can select the alignment and choose properties, and we have several options to define our alignment.

06:47

If we want to group this with the other center lines, we can define that here.

06:53

We'll do the same thing for the Southbound lane.

06:55

We'll define it on the right side relative to the stationing,

06:60

then we'll set up the similar parameters as we did with the Northbound offset alignment.