detect lines in a NetworkDataset without connection

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06-03-2013 10:30 AM
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New Contributor
Hi guys,

I have a NetworkDataset with the following problem:

I load a Shapefile with streets of a area into a NetworkDataset. But there are a lot of lines without a connection to the network. When I load my files with the start- and endpoints, the analyst snap a few points to those lines, without a connection to the rest of the network and the track can not be routed.

I want to detect the lines without connection, but I don't know how... Has the NetworkAnalyst a solution therefor?

Greetz and thanks! 🙂
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MVP Esteemed Contributor
You could also create a topology and check for dangles.  You get a lot of 'false positives' with dead end streets, but depending on your data, it can be a first start.

Using network analyst, you can create service areas and look for disconnects there as well.

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Regular Contributor III
Hello,

Unfortunately, there isn't a tool within Network Analyst that would traverse all your links and highlight those that are disconnected. However, you might consider using a geometric network.

There are some tools for tracing geometric network available from the Utility Network Analyst toolbar in ArcMap (you will be able to find disconnected segments, i.e., those ones from which you cannot reach all other network segments) as well as GP tools which you may also call from arcpy if you wish to automate the QA/QC process. I've run these tools on 2 mil.+ segments network and it worked fine.
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You could also create a topology and check for dangles.  You get a lot of 'false positives' with dead end streets, but depending on your data, it can be a first start.

Using network analyst, you can create service areas and look for disconnects there as well.

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Occasional Contributor III
Along with the help Alexey and Joe gave you, there are a couple of other options to try and find disconnected portions of your network.

1 - Use the custom connectivity solver here:

http://help.arcgis.com/en/sdk/10.0/arcobjects_net/conceptualhelp/index.html#//000100000n99000000

O
nce you have this solver running in ArcMap, you can choose to highlight disconnected areas of your network.  This solver does pretty much exactly what you want.

2 - Use Service Area. 

   Turn on lines and turn off polygons for service area.  Place facilities as a kind of seed point, then solve large service areas that would cover most, if not all of your network.
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