Trimble Business Center

Please see attached photo.  The two white lines are centerline alignments of northbound and southbound railways.   I am trying to get a line created directly in the middle of the two. The line doesnt need vertical elements, only horizontal.   THe only way i can think to do it is manually draw perpendicular lines between the two and select the midpoint. But wondering if there is an easier more accurate solution.  Of course the alignments vary in width from eachother and have spiral curves in and out with different start locations so its not as simple as offsetting one of the lines.

Thanks

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sean maxwell
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Bad idea

A quick way, without an extra macro, would be to utilize Alignment Labels.
Then clip them.
Use create from CAD.
Connect the points.


The result will be different depending on which line you create the perpendicular label lines from.


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Ronny Schneider
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Original Message:
Sent: 05-13-2022 12:47
From: sean maxwell
Subject: Create Centerline between two alignments

Please see attached photo.  The two white lines are centerline alignments of northbound and southbound railways.   I am trying to get a line created directly in the middle of the two. The line doesnt need vertical elements, only horizontal.   THe only way i can think to do it is manually draw perpendicular lines between the two and select the midpoint. But wondering if there is an easier more accurate solution.  Of course the alignments vary in width from eachother and have spiral curves in and out with different start locations so its not as simple as offsetting one of the lines.

Thanks

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sean maxwell
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Also rather bad idea

Another way that just popped to mind.
Create points at intervals and use the Best-Fit-Line.

It all depends what you actually need it for? What are the design rules/limitations?

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Ronny Schneider
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Original Message:
Sent: 05-13-2022 12:47
From: sean maxwell
Subject: Create Centerline between two alignments

Please see attached photo.  The two white lines are centerline alignments of northbound and southbound railways.   I am trying to get a line created directly in the middle of the two. The line doesnt need vertical elements, only horizontal.   THe only way i can think to do it is manually draw perpendicular lines between the two and select the midpoint. But wondering if there is an easier more accurate solution.  Of course the alignments vary in width from eachother and have spiral curves in and out with different start locations so its not as simple as offsetting one of the lines.

Thanks

------------------------------
sean maxwell
------------------------------

You could create a corridor using one of the alignments, and assign the other alignment as a reference line.  Then when you create a corridor template your #1 node will be the alignment and the #2 node will be the reference alignment.  If the vertical alignments are different, which I'm sure they are, then create a third node using offset/elevation instruction type, with the offset set to zero and the elevation using node to node and choose from 1 to 2.  This will give you a node #3 in the same horizontal location as the alignment with the same elevation as the other reference alignment.  Then add another instruction with the slope/slope type, the first slope node will be #2 and the second slope node will be #3 it doesn't matter what slope you choose just not zero, probably 2:1 would be good just be sure to make them both the same.  This will create a node #4 exactly in the center.  Then select the corridor surface that you put node #4 on and densify it then explode it and you'll have very close to perfect.  At that point you could probably try using rockpile's optimize linestrings to see if it can come up with an actual curvilinear alignment that works.​​​​​​​​

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Wayne Welshans
------------------------------

Original Message:
Sent: 05-13-2022 12:47
From: sean maxwell
Subject: Create Centerline between two alignments

Please see attached photo.  The two white lines are centerline alignments of northbound and southbound railways.   I am trying to get a line created directly in the middle of the two. The line doesnt need vertical elements, only horizontal.   THe only way i can think to do it is manually draw perpendicular lines between the two and select the midpoint. But wondering if there is an easier more accurate solution.  Of course the alignments vary in width from eachother and have spiral curves in and out with different start locations so its not as simple as offsetting one of the lines.

Thanks

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sean maxwell
------------------------------

Didn't think of that one, though I've used it before. Waynes solution will give you a slightly better result than my first proposal. It does have the advantage to use the densification, have longer polyline segments on straights and shorter ones in curves.
But as with my proposal it all depends which alignment you choose as "master" alignment. All computations will be perpendicular to that one and if the curvature of the alignments is very different you'll get different results.

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Ronny Schneider
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Original Message:
Sent: 05-16-2022 13:31
From: Wayne Welshans
Subject: Create Centerline between two alignments

You could create a corridor using one of the alignments, and assign the other alignment as a reference line.  Then when you create a corridor template your #1 node will be the alignment and the #2 node will be the reference alignment.  If the vertical alignments are different, which I'm sure they are, then create a third node using offset/elevation instruction type, with the offset set to zero and the elevation using node to node and choose from 1 to 2.  This will give you a node #3 in the same horizontal location as the alignment with the same elevation as the other reference alignment.  Then add another instruction with the slope/slope type, the first slope node will be #2 and the second slope node will be #3 it doesn't matter what slope you choose just not zero, probably 2:1 would be good just be sure to make them both the same.  This will create a node #4 exactly in the center.  Then select the corridor surface that you put node #4 on and densify it then explode it and you'll have very close to perfect.  At that point you could probably try using rockpile's optimize linestrings to see if it can come up with an actual curvilinear alignment that works.​​​​​​​​

------------------------------
Wayne Welshans

Original Message:
Sent: 05-13-2022 12:47
From: sean maxwell
Subject: Create Centerline between two alignments

Please see attached photo.  The two white lines are centerline alignments of northbound and southbound railways.   I am trying to get a line created directly in the middle of the two. The line doesnt need vertical elements, only horizontal.   THe only way i can think to do it is manually draw perpendicular lines between the two and select the midpoint. But wondering if there is an easier more accurate solution.  Of course the alignments vary in width from eachother and have spiral curves in and out with different start locations so its not as simple as offsetting one of the lines.

Thanks

------------------------------
sean maxwell
------------------------------

This is the method I use/recommend also. 

Rob

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Rob Davidson
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Original Message:
Sent: 05-16-2022 13:31
From: Wayne Welshans
Subject: Create Centerline between two alignments

You could create a corridor using one of the alignments, and assign the other alignment as a reference line.  Then when you create a corridor template your #1 node will be the alignment and the #2 node will be the reference alignment.  If the vertical alignments are different, which I'm sure they are, then create a third node using offset/elevation instruction type, with the offset set to zero and the elevation using node to node and choose from 1 to 2.  This will give you a node #3 in the same horizontal location as the alignment with the same elevation as the other reference alignment.  Then add another instruction with the slope/slope type, the first slope node will be #2 and the second slope node will be #3 it doesn't matter what slope you choose just not zero, probably 2:1 would be good just be sure to make them both the same.  This will create a node #4 exactly in the center.  Then select the corridor surface that you put node #4 on and densify it then explode it and you'll have very close to perfect.  At that point you could probably try using rockpile's optimize linestrings to see if it can come up with an actual curvilinear alignment that works.​​​​​​​​

------------------------------
Wayne Welshans

Original Message:
Sent: 05-13-2022 12:47
From: sean maxwell
Subject: Create Centerline between two alignments

Please see attached photo.  The two white lines are centerline alignments of northbound and southbound railways.   I am trying to get a line created directly in the middle of the two. The line doesnt need vertical elements, only horizontal.   THe only way i can think to do it is manually draw perpendicular lines between the two and select the midpoint. But wondering if there is an easier more accurate solution.  Of course the alignments vary in width from eachother and have spiral curves in and out with different start locations so its not as simple as offsetting one of the lines.

Thanks

------------------------------
sean maxwell
------------------------------

Set both alignments to elevation 1.00, offset each alignment 100' and vertically 1' across each other. For instance NB offset 100' *west and SB 100' *east.  make surfaces out of the NB and its offset and the SB and its offset. Run the surface intersection and they will intersect in the middle.



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Robert Barton
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Original Message:
Sent: 05-13-2022 12:47
From: sean maxwell
Subject: Create Centerline between two alignments

Please see attached photo.  The two white lines are centerline alignments of northbound and southbound railways.   I am trying to get a line created directly in the middle of the two. The line doesnt need vertical elements, only horizontal.   THe only way i can think to do it is manually draw perpendicular lines between the two and select the midpoint. But wondering if there is an easier more accurate solution.  Of course the alignments vary in width from eachother and have spiral curves in and out with different start locations so its not as simple as offsetting one of the lines.

Thanks

------------------------------
sean maxwell
------------------------------

Haven't thought of that one either. Very good idea and offsetting the linestrings is the best solution since it keeps everything perpendicular to each string.

You might want to go into the project settings and lower the Maximum Sampling Distance. That way you can create additional nodes on straight segments and hence additional triangles in your surfaces. The denser those surfaces are the more accurate the intersection linestring will be.



Since offsetting the lines is the best solution you can also try the Slope-Slope-Intersect Macro, that should have been installed with TBC. I don't know how it computes internally, if it keeps everything perpendicular to each string, you might want to compare the result to the DTM-Intersect-Solution. A quick compare with my two simple strings shows differences in the 5th decimal, so nearly nothing.

Important for both is to create a copy of the alignments and change the heights to a uniform level.

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Ronny Schneider
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Original Message:
Sent: 05-17-2022 07:23
From: Robert Barton
Subject: Create Centerline between two alignments

Set both alignments to elevation 1.00, offset each alignment 100' and vertically 1' across each other. For instance NB offset 100' *west and SB 100' *east.  make surfaces out of the NB and its offset and the SB and its offset. Run the surface intersection and they will intersect in the middle.



------------------------------
Robert Barton

Original Message:
Sent: 05-13-2022 12:47
From: sean maxwell
Subject: Create Centerline between two alignments

Please see attached photo.  The two white lines are centerline alignments of northbound and southbound railways.   I am trying to get a line created directly in the middle of the two. The line doesnt need vertical elements, only horizontal.   THe only way i can think to do it is manually draw perpendicular lines between the two and select the midpoint. But wondering if there is an easier more accurate solution.  Of course the alignments vary in width from eachother and have spiral curves in and out with different start locations so its not as simple as offsetting one of the lines.

Thanks

------------------------------
sean maxwell
------------------------------