How do I find three-way intersections?

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02-28-2020 06:09 AM
PaulFrissora1
New Contributor

I have two layers: Layer A has Junctions as a Point file; Layer B has edges as a Line File. 

 

The problem: I'm looking for junctions that are intersected by three (no more, no less) lines. Like this: 

              

                                                                     \

                                                                       \   

                                                                         x-------------                                                                                                                                                                             /

                                                                     /

 

I'm looking for a way to find these junctions with either a selection of by making a separate shapefile. It seems the way to do this might be through creating a Geometric Network or Network Analyst dataset, but I haven't been able to find much info in the forums and documentation online. 

 

Has anyone done this before?  

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MikeMillerGIS
Esri Frequent Contributor

If you create a geometric network, you can take advantage of the Select Junction by Edge count tool in the water utility add in.

Water Utility Network Reporting toolbar - Water Utility Network Editing and Analysis | ArcGIS Soluti... 

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3 Replies
MikeMillerGIS
Esri Frequent Contributor

If you create a geometric network, you can take advantage of the Select Junction by Edge count tool in the water utility add in.

Water Utility Network Reporting toolbar - Water Utility Network Editing and Analysis | ArcGIS Soluti... 

PaulFrissora1
New Contributor

Thank you! This worked perfectly

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RobertBorchert
Frequent Contributor III

Are your lines broken at the intersections?

Create points from the end points of your lines.  populate them with X,Y

bring them into MS Access and run a query to look for duplicates. 

If the lines are not broken at intersections then generate points of vertices.

It sounds like your not already in a geometric network, so you will probably have lines that are really close to each other but not actually touching. So then use the points and the Generate Near Table analysis to find lines and the distance to them. If it is only a few inches to feet then it is an area to look at first.

This all makes a strong case for a geometric network, it gives you assurance that everything is connected and more accurate.

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