1

Although reasonably experienced with ArcGIS I am a bit of a newbie with Network analyst. I have a situation in which things work Ok with the tutorial data but not with mine!

I am trying to determine an 8km road distance from a set of hospitals in East Africa. I have some roads data that I can build into a network. As far as I can see there is full connectivity. If I work using detailed polygons (which is what I want) I get this.

net2

So the "service area does not go along roads A,B and C, which I would expect it to. and how on earth does it think I am going to get to Point D!!.

Using generalised polygons I get this:

net2

Now I have lost the slightly anomalous point D, but the services area still does not traverse roads A and B.

I am using ArcGIS 10.2 for Desktop.

  • I find the images very small and hard to read. Also it appears they are hosted off-site - it's better to use the picture icon above the editing box to embed your images so that a copy is permanently included should you delete it or it be otherwise removed from flickr. Regarding D and the detailed polygons, you may want to take a look at this question. Per the answer below, it doesn't look like A and B are connected to the network or there is a barrier in place. Or a connectivity policy issue. – Chris W Dec 1 '14 at 21:39
  • OK, it looks like it was connectivity policy. Thanks for that and the tips on images – Rob Corner Dec 2 '14 at 0:18
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With respect to A,B,C:

  1. try checking your network with the topology tool, every "line" must be connected to an other line by a "point"(http://resources.arcgis.com/en/help/main/10.1/index.html#//004700000009000000). Sometimes I get the same problem, you can solve it by connecting the errors or - sometimes it´s much faster - edit a new line.

  2. If you use barriers or other rules, then in OSM for example there are point barriers, like gates, or line rules, like private roads. You can´t travel them - if you use rules like that.

With respect to D, it looks like wrong "interpolation" of the GIS, also get sometimes errors like this.

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