How to debug network analyst problems - endpoint routes work, vertex do not

Question

I have a feature class that is comprised of roads in a country. I've created a network that includes this feature class with the following relevant options:

1. Vertex connectivity (not end point).
2. No elevation modeling
3. Length as cost attribute is the only attribute
4. Global turns

When I attempt to complete analysis tasks such as OD matrix or even Route, the only paths that are found are those where the points are on the same edge or on edges connected via endpoint. I've taken a good look at this and as soon as I place the next point of the route onto an edge that is joined by intersection, the error dialog pops up saying there is not path to that next point.

What should I do next?

JaySandhu · Answer

Looks like you do not have good connectivity in your network to find the desired routes.
You say you are using Vertex connectivity. Do you have common vertices among lines that cross for them to be able to connect to each other? If not, you can run Intergrate. More help here:
http://help.arcgis.com/en/arcgisdesktop/10.0/help/index.html#//00170000002s000000.htm
 
Is there a reason you did not use end point connectivity?
 
To make sure it is a connectivity issue, you can use the Network Identify tool (second button from right on the NA toolbar) to click on an edge and see what it is connected to.
 
Regards,
Jay Sandhu

AndyGarcia · Answer

I am using ArcGIS 10.0 with an ArcInfo license.

The road network is for a region without much complexity, I'm looking for a barebones analysis of distances between points using the network. Not worried about hierarchy, restrictions, etc. right now.

JoeBorgione · Answer

I have a feature class that is comprised of roads in a country. I've created a network that includes this feature class with the following relevant options:

1. Vertex connectivity (not end point).
2. No elevation modeling
3. Length as cost attribute is the only attribute
4. Global turns

When I attempt to complete analysis tasks such as OD matrix or even Route, the only paths that are found are those where the points are on the same edge or on edges connected via endpoint. I've taken a good look at this and as soon as I place the next point of the route onto an edge that is joined by intersection, the error dialog pops up saying there is not path to that next point.

What should I do next?

What version of ArcGIS are you using? If it's 10.x, let'st hope that Jay or one of the other NA team members can help you out.  I've not taken the plunge and still using 9.3.1.

Something I would suggest however is re-thinking the connectivity issue.  If your data is from a legacy ArcInfo coverage data model, you will have coincident vertexes for freeway over passes and the freeways themselves.  You'll be routing incorrectly with that situation.