• Civil 3D

Create rail alignments

Use several different methods to create rail alignments in Civil 3D.


00:00

In this video, we'll look at several different methods for creating rail alignments for either existing or proposed alignments.

00:11

We'll also take a look at some ways to create some very complex geometry to avoid conflicts or fouling points.

00:19

So, in the first example we have 3D Poly lines that were extracted from a point cloud.

00:24

So, in the Autodesk construction cloud, we can extract key features like rail lines or platform edge lines from the cloud,

00:31

and we can use those 3D lines in Civil 3D as a basis for our alignment.

00:36

We can also see that these lines are in the correct Geo reference location.

00:40

So, on the Home tab, we can choose alignments and pick Create Best Fit alignment.

00:46

With this option, we can choose between AutoCAD entities like Poly lines or blocks, COGO points, or in this case,

00:53

we'll actually choose feature lines.

00:55

We can use the selection tool to pick the left rail for the first line and the right rail as the second line.

01:01

We'll increase the maximum radius just to be sure that we are including some of the larger curves that may exist on this alignment.

01:09

We can also adjust the spiral to curve value here, and this is a value that we can revise if we need to adjust our results.

01:16

We have the option to match tangents and spirals.

01:19

This option tends to make the alignment a lot less symmetrical.

01:23

For the other items, we'll leave them as default. We can also adjust the weeding options here,

01:28

and we can also control the maximum angle or distance, but we'll leave these off for now as well.

01:34

Once we select OK, we'll see a regression graph that will show the location of the solved alignment.

01:40

We can expect that to review the outcomes.

01:44

Once we close the window, the alignment will display.

01:47

And keep in mind once the alignment is set, we can adjust the values and the cardinal points if we need to

01:52

and can see some of the values or the links might need to be adjusted for a better fit.

01:57

And some of the things we can review and adjust as needed in the geometry editor.

02:02

In this example, we can select the alignment and go to the alignment properties.

02:06

Since we created this as a best fit alignment, we'll change this to a rail alignment.

02:11

In the design criteria tab, we can add some speed values and determine the specific criteria for our project.

02:19

And here we'll just use the default metric rail standards.

02:22

Now let's create an alignment from COGO points or survey points.

02:27

So here we want to start on the rail tab.

02:29

We can identify our alignment properties and include the name, stationing, and design criteria.

02:37

So, with the geometry editor toolbar, we can create individual elements of our alignments like the tangents and the curves.

02:45

So, let's start with the first tangent.

02:47

In the tangent drop-down, we can pick from a few options.

02:51

We'll pick the fixed line best fit.

02:53

We have some options here to choose from, but let's select COGO points.

02:57

You can see in general where the tangent is located.

03:00

But even if we choose some points that are outside of that tangent, we can edit those in the window.

03:06

So, when we pick the points, we can see our regression graph.

03:09

So, if we need to exclude some of those points from the tangent section, we can do this,

03:14

and the graph will update to show the solved tangent section.

03:19

Once we get that to where it looks accurate, we can close the window.

03:23

Once that window is closed, the tangent section will appear.

03:27

And since this alignment is a freight line, we want to define this by chord definition.

03:32

So, let's pick the alignment and go to the alignment properties.

03:37

Under the station control tab, we can select chord definition.

03:41

We could also add our design speed to our alignment and then those labels will appear for the alignment.

03:49

In our case, the station is exactly going the wrong direction.

03:53

So, if this is the case, we select the alignment and pick the drop down from the modify menu and choose reverse direction.

04:01

So, once we select the prompt, we can see that the alignment is revised.

04:05

Now let's pick the curve section.

04:07

We'll do something similar by choosing the curve drop-down.

04:12

And for clarification, a fixed curve will be based on certain elements, and here those will be based on COGO points.

04:18

The floating curves are fixed on one end to another element of the alignment,

04:23

and free curves are calculated between two existing elements.

04:27

So, we'll choose the fixed curve for best fit, and we'll go through the similar workflow based on the COGO points,

04:33

pick the points that look like they're in the body of the curve.

04:36

Similarly, we can exclude points that are outside, based on our regression analysis.

04:42

And now we have a separate curve from the tangent.

04:45

These are both part of the same alignment even though they don't connect.

04:49

And we'll do the same thing all the way up our alignment for the rest of the tangents and the curves.

04:55

Now we want to connect these tangents and curves with spirals, so we'll pick the free spiral from the spiral drop-down list.

05:03

And in our case, it actually tells us that there's no solution found when we pick the two options.

05:07

We may need to actually reverse the direction of our curve element.

05:13

So, we can pick the reverse direction tool in our toolbar and pick the curve.

05:19

Now when we create a connecting spiral, we can see the results are connecting the two elements.

05:24

We can do the same thing all the way up the alignment.

05:27

So, this is another way that we can create existing alignments based on field data or point cloud data.

05:35

And all of our curve elements are identified when we review the alignment in this window.

05:41

So let's look at creating proposed alignment by laying out PI locations.

05:46

So we've identified the PI locations in this example with circles, but we could do this a number of different ways.

05:52

We could use construction lines or a dummy layout.

05:54

In the rail tab, we'll pick the creation tools and populate the information for our alignment.

06:00

We'll pick the PI tool and we can go through the alignment and snap to all those PI locations.

06:10

We'll do the same thing for the southbound track.

06:17

Now we want to create spiralized curves for each PI location.

06:21

One item of note, we can choose from several different spiral types, depending on our project requirement.

06:27

And we can change that in the PI drop-down by selecting Spiral.

06:31

For this option, we'll just stay with Clothoid.

06:33

To make the spiral curves, we can pick the drop-down menu here, and we'll pick a free curve.

06:39

Again, a free curve is calculated between.

06:41

If we're not sure which method we want to choose,

06:43

if we look at the parentheses, we can determine what factors we're basing the curve on.

06:48

So once we pick that option, we'll pick the first, then the second element, then input the curve radius and the spiral lengths.

06:55

These values should be based on our design speed and our design criteria, and if they're outside of that,

07:00

will receive a warning notice on those curves or spirals.

07:05

We'll do this both for the northbound and the southbound alignment.

07:10

Looking at some more complex examples, let's take a look at some other methods for laying out some rail alignments.

07:16

We can create alignments from objects, but since we can't realistically draw a spiral, we'll end up getting geometry that we may not like.

07:26

So we'll pick the alignment from objects, define the direction of our stationing, then input some alignment parameters.

07:34

If, when we create the alignment, we don't see any labels, we can add those by picking the alignment and choosing Edit Alignment Labels

07:41

with the right-click menu.

07:44

Here we can add cardinal points, stationing, or other labels that we might need.

07:49

Once those display, we can see we have a number of curves representing the spiral.

07:54

So if we use the grips and edit the alignment, the other elements actually don't update with the grips.

08:01

If we need to create an alignment from objects, it's best to redefine the curve geometry by using edit alignment tools

08:09

and then deleting the curve and recreating it with spirals.

08:17

In the next example, we want to take a look at an existing alignment where we may need to avoid conflicts by creating a compound curve,

08:25

or we may want to see what to do if we have multiple items that we need to avoid.

08:30

So here, we'll remove the existing curve and show just the tangent in and out.

08:35

To create a compound curve, we can pick the spiralized curve drop-down,

08:40

and then select compound spiral curve, spiral curve, spiral between two tangents.

08:46

Once we input the parameters, we'll see a preview of the solved alignment.

08:52

We could also base the curvature on a through point, a begin point, or an end point.

08:56

If we don't see that preview solution, we may need to adjust our curve parameters.

09:01

Next, we've identified several conflict points with their clearance distance.

09:07

In this case, we need to base our alignment on those clearance envelopes.

09:12

So we'll lay out this alignment a segment at a time to make sure that we optimize our geometry.

09:17

So we'll pick the floating curve with a spiral from a point with a radius and a through point.

09:23

So we'll pick our tangent, provide the curve and spiral parameters, then we can pick the tangent point based on that clearance envelope.

09:33

We can do the same thing for the next curve, the same function, but with different parameters.

09:38

Then to end the curve, we can add a floating line with a spiral.

09:43

However, in our case this doesn't match our required tangent out of this curve.

09:49

So to make sure that we close this curve on the correct tangent, we'll create a tangent, then add a close out spiral to complete the curve.

09:58

We'll add a free curve between two elements.

10:02

And the length will be calculated automatically.

10:05

And again, if we need to get in and revise or edit the alignment parameters, we can do that with grips, or in the geometry table.

Video transcript

00:00

In this video, we'll look at several different methods for creating rail alignments for either existing or proposed alignments.

00:11

We'll also take a look at some ways to create some very complex geometry to avoid conflicts or fouling points.

00:19

So, in the first example we have 3D Poly lines that were extracted from a point cloud.

00:24

So, in the Autodesk construction cloud, we can extract key features like rail lines or platform edge lines from the cloud,

00:31

and we can use those 3D lines in Civil 3D as a basis for our alignment.

00:36

We can also see that these lines are in the correct Geo reference location.

00:40

So, on the Home tab, we can choose alignments and pick Create Best Fit alignment.

00:46

With this option, we can choose between AutoCAD entities like Poly lines or blocks, COGO points, or in this case,

00:53

we'll actually choose feature lines.

00:55

We can use the selection tool to pick the left rail for the first line and the right rail as the second line.

01:01

We'll increase the maximum radius just to be sure that we are including some of the larger curves that may exist on this alignment.

01:09

We can also adjust the spiral to curve value here, and this is a value that we can revise if we need to adjust our results.

01:16

We have the option to match tangents and spirals.

01:19

This option tends to make the alignment a lot less symmetrical.

01:23

For the other items, we'll leave them as default. We can also adjust the weeding options here,

01:28

and we can also control the maximum angle or distance, but we'll leave these off for now as well.

01:34

Once we select OK, we'll see a regression graph that will show the location of the solved alignment.

01:40

We can expect that to review the outcomes.

01:44

Once we close the window, the alignment will display.

01:47

And keep in mind once the alignment is set, we can adjust the values and the cardinal points if we need to

01:52

and can see some of the values or the links might need to be adjusted for a better fit.

01:57

And some of the things we can review and adjust as needed in the geometry editor.

02:02

In this example, we can select the alignment and go to the alignment properties.

02:06

Since we created this as a best fit alignment, we'll change this to a rail alignment.

02:11

In the design criteria tab, we can add some speed values and determine the specific criteria for our project.

02:19

And here we'll just use the default metric rail standards.

02:22

Now let's create an alignment from COGO points or survey points.

02:27

So here we want to start on the rail tab.

02:29

We can identify our alignment properties and include the name, stationing, and design criteria.

02:37

So, with the geometry editor toolbar, we can create individual elements of our alignments like the tangents and the curves.

02:45

So, let's start with the first tangent.

02:47

In the tangent drop-down, we can pick from a few options.

02:51

We'll pick the fixed line best fit.

02:53

We have some options here to choose from, but let's select COGO points.

02:57

You can see in general where the tangent is located.

03:00

But even if we choose some points that are outside of that tangent, we can edit those in the window.

03:06

So, when we pick the points, we can see our regression graph.

03:09

So, if we need to exclude some of those points from the tangent section, we can do this,

03:14

and the graph will update to show the solved tangent section.

03:19

Once we get that to where it looks accurate, we can close the window.

03:23

Once that window is closed, the tangent section will appear.

03:27

And since this alignment is a freight line, we want to define this by chord definition.

03:32

So, let's pick the alignment and go to the alignment properties.

03:37

Under the station control tab, we can select chord definition.

03:41

We could also add our design speed to our alignment and then those labels will appear for the alignment.

03:49

In our case, the station is exactly going the wrong direction.

03:53

So, if this is the case, we select the alignment and pick the drop down from the modify menu and choose reverse direction.

04:01

So, once we select the prompt, we can see that the alignment is revised.

04:05

Now let's pick the curve section.

04:07

We'll do something similar by choosing the curve drop-down.

04:12

And for clarification, a fixed curve will be based on certain elements, and here those will be based on COGO points.

04:18

The floating curves are fixed on one end to another element of the alignment,

04:23

and free curves are calculated between two existing elements.

04:27

So, we'll choose the fixed curve for best fit, and we'll go through the similar workflow based on the COGO points,

04:33

pick the points that look like they're in the body of the curve.

04:36

Similarly, we can exclude points that are outside, based on our regression analysis.

04:42

And now we have a separate curve from the tangent.

04:45

These are both part of the same alignment even though they don't connect.

04:49

And we'll do the same thing all the way up our alignment for the rest of the tangents and the curves.

04:55

Now we want to connect these tangents and curves with spirals, so we'll pick the free spiral from the spiral drop-down list.

05:03

And in our case, it actually tells us that there's no solution found when we pick the two options.

05:07

We may need to actually reverse the direction of our curve element.

05:13

So, we can pick the reverse direction tool in our toolbar and pick the curve.

05:19

Now when we create a connecting spiral, we can see the results are connecting the two elements.

05:24

We can do the same thing all the way up the alignment.

05:27

So, this is another way that we can create existing alignments based on field data or point cloud data.

05:35

And all of our curve elements are identified when we review the alignment in this window.

05:41

So let's look at creating proposed alignment by laying out PI locations.

05:46

So we've identified the PI locations in this example with circles, but we could do this a number of different ways.

05:52

We could use construction lines or a dummy layout.

05:54

In the rail tab, we'll pick the creation tools and populate the information for our alignment.

06:00

We'll pick the PI tool and we can go through the alignment and snap to all those PI locations.

06:10

We'll do the same thing for the southbound track.

06:17

Now we want to create spiralized curves for each PI location.

06:21

One item of note, we can choose from several different spiral types, depending on our project requirement.

06:27

And we can change that in the PI drop-down by selecting Spiral.

06:31

For this option, we'll just stay with Clothoid.

06:33

To make the spiral curves, we can pick the drop-down menu here, and we'll pick a free curve.

06:39

Again, a free curve is calculated between.

06:41

If we're not sure which method we want to choose,

06:43

if we look at the parentheses, we can determine what factors we're basing the curve on.

06:48

So once we pick that option, we'll pick the first, then the second element, then input the curve radius and the spiral lengths.

06:55

These values should be based on our design speed and our design criteria, and if they're outside of that,

07:00

will receive a warning notice on those curves or spirals.

07:05

We'll do this both for the northbound and the southbound alignment.

07:10

Looking at some more complex examples, let's take a look at some other methods for laying out some rail alignments.

07:16

We can create alignments from objects, but since we can't realistically draw a spiral, we'll end up getting geometry that we may not like.

07:26

So we'll pick the alignment from objects, define the direction of our stationing, then input some alignment parameters.

07:34

If, when we create the alignment, we don't see any labels, we can add those by picking the alignment and choosing Edit Alignment Labels

07:41

with the right-click menu.

07:44

Here we can add cardinal points, stationing, or other labels that we might need.

07:49

Once those display, we can see we have a number of curves representing the spiral.

07:54

So if we use the grips and edit the alignment, the other elements actually don't update with the grips.

08:01

If we need to create an alignment from objects, it's best to redefine the curve geometry by using edit alignment tools

08:09

and then deleting the curve and recreating it with spirals.

08:17

In the next example, we want to take a look at an existing alignment where we may need to avoid conflicts by creating a compound curve,

08:25

or we may want to see what to do if we have multiple items that we need to avoid.

08:30

So here, we'll remove the existing curve and show just the tangent in and out.

08:35

To create a compound curve, we can pick the spiralized curve drop-down,

08:40

and then select compound spiral curve, spiral curve, spiral between two tangents.

08:46

Once we input the parameters, we'll see a preview of the solved alignment.

08:52

We could also base the curvature on a through point, a begin point, or an end point.

08:56

If we don't see that preview solution, we may need to adjust our curve parameters.

09:01

Next, we've identified several conflict points with their clearance distance.

09:07

In this case, we need to base our alignment on those clearance envelopes.

09:12

So we'll lay out this alignment a segment at a time to make sure that we optimize our geometry.

09:17

So we'll pick the floating curve with a spiral from a point with a radius and a through point.

09:23

So we'll pick our tangent, provide the curve and spiral parameters, then we can pick the tangent point based on that clearance envelope.

09:33

We can do the same thing for the next curve, the same function, but with different parameters.

09:38

Then to end the curve, we can add a floating line with a spiral.

09:43

However, in our case this doesn't match our required tangent out of this curve.

09:49

So to make sure that we close this curve on the correct tangent, we'll create a tangent, then add a close out spiral to complete the curve.

09:58

We'll add a free curve between two elements.

10:02

And the length will be calculated automatically.

10:05

And again, if we need to get in and revise or edit the alignment parameters, we can do that with grips, or in the geometry table.

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