• Civil 3D

Calculate rail cant

Use Civil 3D to set up rail alignment and calculate rail cant, including for tangent sections.


00:00

In this video, we will set up our alignment and calculate rail cant.

00:08

We'll also look at some of the new features and tools where we can add cant to specific locations on our alignment,

00:16

including tangent sections.

00:18

To begin, we need to set up our alignment prior to calculating the cant.

00:22

So, let's select the eastbound track and go to Alignment Properties.

00:26

We need to verify the alignment is a rail alignment.

00:30

In this case it is, and we can change that here if needed.

00:33

Under the design criteria, we can specify our design criteria, and it tells us we need to set our alignment speed first.

00:41

So, let's set that up now.

00:43

Based on this alignment, we need to set up a few design speed areas.

00:47

We have our first limit, and then we can set additional limits based on the station location and the speed.

00:55

When we use the selection tool, we can pick those station limits in plan view.

00:59

We can adjust the speed as needed, and we'll do this for the rest of our alignment.

01:05

Once we select OK, our label styles will show the speed locations.

01:10

We can review those if needed.

01:12

We can also move these labels if we have any conflicts using the grips.

01:16

And then we'll add the design speed locations for the westbound track as well with the same process.

01:22

And if we have overlapping labels, we can hold control, then select the label, then right-click to flip the label.

01:31

At this location, we can actually see that the eastbound limit is not in the right location, it's in the spiral.

01:36

So, we can easily edit this value and update it once we apply the new limit.

01:41

So once that's set, we'll do some last clean-up, and then we should be set for our design speeds.

01:49

Looking at a few items in alignment properties, we can look at the track width.

01:53

The default value gives the center-to-center spacing, but we can change that to the gauge width,

01:58

or we can adjust it, depending on our rail size. In this case, we're using 50-kilogram rail.

02:04

For now, we'll leave the default values.

02:07

Since we have our speed set, we can determine the criteria we're using.

02:10

Again, we'll stay with the default metric criteria.

02:14

We can review some of the other tabs.

02:15

We don't really need to change anything.

02:17

We'll stay with the defaults.

02:19

And if we're using freight rail, we could set this to cord definition under the Station Control tab.

02:24

The default setting is for ARC definition, so we'll leave this as it is for now.

02:28

Everything else looks okay.

02:31

So, under the Rail tab, we'll choose Calculate.

02:34

Then we'll pick our alignment, and we'll choose to Calculate now.

02:37

The track width is based on the value that we set in our alignment properties,

02:40

and we'll determine the method of super elevation, whether it's the low rail, high rail, or center.

02:47

We'll stay with the low rail setting.

02:49

The criteria is based on our design speed, but we could adjust those values here as well.

02:53

Once we select finish, we will see the calculated values and the station locations with the applied cant

02:58

and we can see the other values in the table.

03:01

If needed, we can adjust any of those values in this table.

03:06

In this example, we've already calculated the applied cant and the spiral links in a spreadsheet, and I want to match those values.

03:14

So, I can compare the values and adjust the table by picking the cells and revising them.

03:19

When I select the cell, the corresponding alignment element will highlight in Plan view.

03:25

So, once I'm happy with those calculations, I can close the window.

03:30

We'll do the same thing on the westbound side.

03:33

Now if we need to go back and make any revisions to the cant, we can run the same command, the Calculate command.

03:38

This time, we'll see a different window come up.

03:40

This will display the alignment geometry and the criteria.

03:43

In the Cant wizard, I can actually specify the entire alignment or specific curves that need to be recalculated.

03:52

Then, we'll see the same window and the table to indicate the values.

03:59

Then we can view the Cant diagram by selecting Create Cant View,

04:04

and I can pick the alignment, then choose the location of where I want my diagram.

04:10

And this will show us the stations, the transition lengths, the low and the high rail, as well as the equilibrium cant.

04:17

This is valuable information, particularly when we're creating track charts or plan sheets.

04:24

So now, let's look at creating custom cant in tangent sections.

04:29

We have a section of tangent where we want to add cant.

04:32

It could be for a conflict or a platform, really any reason.

04:35

And we can zoom into that area, and we'll choose calculate cant.

04:40

And we'll specify our alignment, in this case, the eastbound.

04:43

And in the cant window, we have the option to choose Create User Defined Curve.

04:49

And when we select this, it will ask for a segment of our alignment.

04:52

So, we will pick this tangent section.

04:55

Zooming out a little bit, we can see that this has highlighted our tangent.

04:59

And as a guide, let's add a line that will show us where we want to add our cant.

05:05

For this, we'll just place a polyline near our track, and then we'll have a transition on either side of this section.

05:11

We'll add a radius to provide a basis for the calculation.

05:15

And so here, we'll add a fairly large value.

05:18

And we can determine the direction of the curve.

05:21

This is going to dictate the rotation of our track, so we'll stay with a left curve, and this will rotate toward our westbound track.

05:30

And we could also revise the speed for this transition as well.

05:34

And we'll keep it as it currently stands.

05:36

Now, once we're set, we'll choose Cant Wizard and the calculation window comes up.

05:41

We only want to redefine this new curve.

05:44

We don't need to change anything else.

05:46

So, we'll select OK, and we'll stay with most of the defaults.

05:49

Again, we're using the metric calculation.

05:52

Once we select Finish, we can see our cant table and we have a number of alerts.

05:57

And this is telling us that we have overlap between areas that we need to correct.

06:03

So, we can define the stations for the transition locations.

06:07

And we'll do that now.

06:08

So, we'll begin by identifying the transition location.

06:11

Next, we'll set the full cant station.

06:15

Then we'll define the end full cant location.

06:19

And again, these are loosely based on our polyline.

06:23

And then finally, the begin level track station.

06:26

And this gives us about 60 meters on each side for transition.

06:31

And we want to redefine those cant values, and we'll set this to 50mm.

06:36

So, as we select each location, we can see a marker in plan view to give us an idea of where these transition locations are.

06:45

This is a really great sanity check.

06:47

The rest of our alignment will remain as we set earlier and then we'll go back to our cant view diagram,

06:54

and we can see the new user defined information: where the transition locations are, as well as the full cant values.

07:03

The final thing we'll look at is how we can use the cant view chart to edit the cant values graphically.

07:10

So, when I select the table, several different grips will appear.

07:14

Here, I'll edit the applied cant value, and I can also input the exact amount that I want, and the chart will update.

07:21

In many cases, we may have very complex cant requirements where we need to change the transition length and rate.

07:28

We can select the chart again using the grips and I can manually adjust the transition location.

07:34

When I hover over the grip, I can add a station to create an inflection point in the transition rate.

07:42

This is extremely helpful when we need to include rate variations or when we have complex geometric situations,

07:49

particularly when it comes to applied can't.

07:52

And I can add as many of these as needed.

07:53

And the tabular editor will also show the station values, and we can edit these as needed.

08:01

So, some tools that really give us complete control over how we want to identify and define the cant for our rail.

Video transcript

00:00

In this video, we will set up our alignment and calculate rail cant.

00:08

We'll also look at some of the new features and tools where we can add cant to specific locations on our alignment,

00:16

including tangent sections.

00:18

To begin, we need to set up our alignment prior to calculating the cant.

00:22

So, let's select the eastbound track and go to Alignment Properties.

00:26

We need to verify the alignment is a rail alignment.

00:30

In this case it is, and we can change that here if needed.

00:33

Under the design criteria, we can specify our design criteria, and it tells us we need to set our alignment speed first.

00:41

So, let's set that up now.

00:43

Based on this alignment, we need to set up a few design speed areas.

00:47

We have our first limit, and then we can set additional limits based on the station location and the speed.

00:55

When we use the selection tool, we can pick those station limits in plan view.

00:59

We can adjust the speed as needed, and we'll do this for the rest of our alignment.

01:05

Once we select OK, our label styles will show the speed locations.

01:10

We can review those if needed.

01:12

We can also move these labels if we have any conflicts using the grips.

01:16

And then we'll add the design speed locations for the westbound track as well with the same process.

01:22

And if we have overlapping labels, we can hold control, then select the label, then right-click to flip the label.

01:31

At this location, we can actually see that the eastbound limit is not in the right location, it's in the spiral.

01:36

So, we can easily edit this value and update it once we apply the new limit.

01:41

So once that's set, we'll do some last clean-up, and then we should be set for our design speeds.

01:49

Looking at a few items in alignment properties, we can look at the track width.

01:53

The default value gives the center-to-center spacing, but we can change that to the gauge width,

01:58

or we can adjust it, depending on our rail size. In this case, we're using 50-kilogram rail.

02:04

For now, we'll leave the default values.

02:07

Since we have our speed set, we can determine the criteria we're using.

02:10

Again, we'll stay with the default metric criteria.

02:14

We can review some of the other tabs.

02:15

We don't really need to change anything.

02:17

We'll stay with the defaults.

02:19

And if we're using freight rail, we could set this to cord definition under the Station Control tab.

02:24

The default setting is for ARC definition, so we'll leave this as it is for now.

02:28

Everything else looks okay.

02:31

So, under the Rail tab, we'll choose Calculate.

02:34

Then we'll pick our alignment, and we'll choose to Calculate now.

02:37

The track width is based on the value that we set in our alignment properties,

02:40

and we'll determine the method of super elevation, whether it's the low rail, high rail, or center.

02:47

We'll stay with the low rail setting.

02:49

The criteria is based on our design speed, but we could adjust those values here as well.

02:53

Once we select finish, we will see the calculated values and the station locations with the applied cant

02:58

and we can see the other values in the table.

03:01

If needed, we can adjust any of those values in this table.

03:06

In this example, we've already calculated the applied cant and the spiral links in a spreadsheet, and I want to match those values.

03:14

So, I can compare the values and adjust the table by picking the cells and revising them.

03:19

When I select the cell, the corresponding alignment element will highlight in Plan view.

03:25

So, once I'm happy with those calculations, I can close the window.

03:30

We'll do the same thing on the westbound side.

03:33

Now if we need to go back and make any revisions to the cant, we can run the same command, the Calculate command.

03:38

This time, we'll see a different window come up.

03:40

This will display the alignment geometry and the criteria.

03:43

In the Cant wizard, I can actually specify the entire alignment or specific curves that need to be recalculated.

03:52

Then, we'll see the same window and the table to indicate the values.

03:59

Then we can view the Cant diagram by selecting Create Cant View,

04:04

and I can pick the alignment, then choose the location of where I want my diagram.

04:10

And this will show us the stations, the transition lengths, the low and the high rail, as well as the equilibrium cant.

04:17

This is valuable information, particularly when we're creating track charts or plan sheets.

04:24

So now, let's look at creating custom cant in tangent sections.

04:29

We have a section of tangent where we want to add cant.

04:32

It could be for a conflict or a platform, really any reason.

04:35

And we can zoom into that area, and we'll choose calculate cant.

04:40

And we'll specify our alignment, in this case, the eastbound.

04:43

And in the cant window, we have the option to choose Create User Defined Curve.

04:49

And when we select this, it will ask for a segment of our alignment.

04:52

So, we will pick this tangent section.

04:55

Zooming out a little bit, we can see that this has highlighted our tangent.

04:59

And as a guide, let's add a line that will show us where we want to add our cant.

05:05

For this, we'll just place a polyline near our track, and then we'll have a transition on either side of this section.

05:11

We'll add a radius to provide a basis for the calculation.

05:15

And so here, we'll add a fairly large value.

05:18

And we can determine the direction of the curve.

05:21

This is going to dictate the rotation of our track, so we'll stay with a left curve, and this will rotate toward our westbound track.

05:30

And we could also revise the speed for this transition as well.

05:34

And we'll keep it as it currently stands.

05:36

Now, once we're set, we'll choose Cant Wizard and the calculation window comes up.

05:41

We only want to redefine this new curve.

05:44

We don't need to change anything else.

05:46

So, we'll select OK, and we'll stay with most of the defaults.

05:49

Again, we're using the metric calculation.

05:52

Once we select Finish, we can see our cant table and we have a number of alerts.

05:57

And this is telling us that we have overlap between areas that we need to correct.

06:03

So, we can define the stations for the transition locations.

06:07

And we'll do that now.

06:08

So, we'll begin by identifying the transition location.

06:11

Next, we'll set the full cant station.

06:15

Then we'll define the end full cant location.

06:19

And again, these are loosely based on our polyline.

06:23

And then finally, the begin level track station.

06:26

And this gives us about 60 meters on each side for transition.

06:31

And we want to redefine those cant values, and we'll set this to 50mm.

06:36

So, as we select each location, we can see a marker in plan view to give us an idea of where these transition locations are.

06:45

This is a really great sanity check.

06:47

The rest of our alignment will remain as we set earlier and then we'll go back to our cant view diagram,

06:54

and we can see the new user defined information: where the transition locations are, as well as the full cant values.

07:03

The final thing we'll look at is how we can use the cant view chart to edit the cant values graphically.

07:10

So, when I select the table, several different grips will appear.

07:14

Here, I'll edit the applied cant value, and I can also input the exact amount that I want, and the chart will update.

07:21

In many cases, we may have very complex cant requirements where we need to change the transition length and rate.

07:28

We can select the chart again using the grips and I can manually adjust the transition location.

07:34

When I hover over the grip, I can add a station to create an inflection point in the transition rate.

07:42

This is extremely helpful when we need to include rate variations or when we have complex geometric situations,

07:49

particularly when it comes to applied can't.

07:52

And I can add as many of these as needed.

07:53

And the tabular editor will also show the station values, and we can edit these as needed.

08:01

So, some tools that really give us complete control over how we want to identify and define the cant for our rail.

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