Converting a digitized shapefile into a network in ARCGis Pro - Standalone user-defined junction is detected

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11-26-2023 02:47 AM
MatteoFilippi
New Contributor
Hi everybody,
 

I am new to ArcGIS. I will briefly present my use case. I have been stuck on this for a while now.

I have an historical map of a railroad network in Italy. I have georeferenced the map and digitized it accordingly. I have now 2 shapefiles, one for the rail (polyline feature), one for the cities (point feature) touched by the rail. In particular, the way I digitized the railroad is the following: each entry in the rail shapefile is the portion of the railroad connecting two successive cities, and the cities should work as junctions of the different portions of the rail connecting each couple of cities. Important: when digitizing, I made sure the snapping tool was active, so that each rail portion connects to a couple of cities. I report a picture of a toy example with 4 cities (point features) and 3 rail portions (polyline features). By clicking on each point, it shows that each point connects to the rail portions as expected.

toy example.png

Now, I would like to convert my point and polyline shapefiles into a network dataset, to perform origin-destination analysis along the rail, using the point features as origins and destinations. Then, I create a network dataset using both my shapefiles as sources. When I build it, I receive the error message "Standalone user-defined junction is detected" for the cities shapefile, ObjectID 1 and 2 (but not 3 and 4!). Apparently, for some reason that I don't understand, ArcGIs does not understand that that the first 2 cities are connected through the first 2 rail portions, but it does understand that the last 2 cities are connected through the last portion. Indeed, using the explore network functionality, if I click on the last rail portion, it is recognized as a network, but nothing happens if I click on the first 2 rail portions.

network.png

Am I missing something? Any kind of help would be truly appreciated. Many thanks in advance!

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3 Replies
DanPatterson
MVP Esteemed Contributor

way at the bottom of this

Network dataset build errors—ArcGIS Pro | Documentation

it states...

Standalone user-defined junction is detected.
The junction feature is not connected to any edges and will not be reachable when routing.

Delete the junction, or edit it or the edges so that it is properly connected.

similar issue found here

Standalone user-defined junction problem - Esri Community


... sort of retired...
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MatteoFilippi
New Contributor

Hi Dan,

Thank you for your reply. The issue is that my junctions are connected (look at my first picture), so I don't know what I am supposed to edit.

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JaySandhu
Esri Regular Contributor

Most likely your cities are NOT connected to BOTH the lines, even though they appear to be. 

However, if your goal is to compute the distances between the cities, you do not need to make them part of the network dataset. You should make the network on just the rail line features. Then check the connectivity of the first or last lines (that is, places where you mention things do not appear to be).

Once you have made sure the connectivity is correct, then create a route analysis layer and load your city location pairs as Stops and solve. The city locations are snapped to the closest location on the network and distances are computed. 

The only reason you want to bring points into a network are cases like providing extra information like costs or adding burn through connectivity when you have anyvertex connectivity.

Jay Sandhu 

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