topic Hierarchy Problem - No Solution Found in ArcGIS Network Analyst Questions

Hierarchy Problem - No Solution Found

RizwanShahid — Wed, 14 Nov 2012 22:34:21 GMT

Hi,

When I have Hierarchy option enabled, I get an error "No Solution Found". Without Hierarchy, it works fine. There are 6 road classes, Hierarchy worked fine when I had Road Class 1-2 combined as Primary Highway, Road Classes 3-4 combined as Secondary Highway, and 5-6 as Local. When I changed Primary Highway from 1-2 to 1-3, rebuilt the dataset and ran the solution, I got an error. Any idea why is it happening?
Thanks in Advance.

R.

Re: Hierarchy Problem - No Solution Found

RamB — Thu, 15 Nov 2012 05:11:37 GMT

Does that mean you also changed the next class as 4 to 6 ? i think the hierarchy values should not overlap.

Re: Hierarchy Problem - No Solution Found

NicoleHanson — Thu, 15 Nov 2012 12:23:27 GMT

So, if I'm understanding you correctly, in the table for the Hierarchy, you have a range of numbers, but it seems one of them over lap. With using Hierarchy, they cannot overlap. It's also easier to have less classes of roads. For instance a 1 for all primary, 2 for secondary, 3 for third traveled and 4 for the least or locals. At least this is what I found out when I use Hierarchy. Hope this helps.

Re: Hierarchy Problem - No Solution Found

RizwanShahid — Thu, 15 Nov 2012 12:34:53 GMT

Thanks Nicole and SK,

The values don't overlap, I don't think it is possible in ArcGIS or even logical to overlap the values. I assigned 1 to 3 values to Primary Roads instead of 1 to 2. Secondary Roads have value of 4 and Local Roads 5 to 6. I hope it makes sense now. There shouldn't be any problem with this change but not sure what is going wrong.

R.

Re: Hierarchy Problem - No Solution Found

NicoleHanson — Thu, 15 Nov 2012 12:57:59 GMT

Can I ask why you have three different values for one set, and two for another? That seems excessive.

Re: Hierarchy Problem - No Solution Found

RizwanShahid — Thu, 15 Nov 2012 13:45:27 GMT

The dataset I am using has Road Class from 1 to 6. Currently, I am using 1 to 3 for Primary, 4 for Secondary, and 5 - 6 for Local.

Previously, I was using 1 and 2 for Primary, 3 and 4 for Secondary and 5-6 for Local but figured out that 3 also represents major roads. It was working fine until I changed Primary from 1 to 2 to 1 to 3.

R.

Re: Hierarchy Problem - No Solution Found

JaySandhu — Thu, 15 Nov 2012 14:24:34 GMT

Most likely the streets coded as level 1 to 3 are not fully connected. According to the online help at:
http://resources.arcgis.com/en/help/main/10.1/#/About_network_analysis_with_hierarchy/004700000057000000/
It states:[INDENT]If the highway is disconnected, the route solver does not descend to the local street and connect. Instead, an error is returned. ArcGIS assumes that the highest order of hierarchy is connected.
[/INDENT]

Also note that hierarchy is useful for long distance routes in very large networks. If you do not have a large street network then you should not add or use hierarchy.

Jay Sandhu

Re: Hierarchy Problem - No Solution Found

RizwanShahid — Thu, 15 Nov 2012 14:27:17 GMT

Thanks Jay. Any suggestion on how to check and make connectivity of hierarchy?

Re: Hierarchy Problem - No Solution Found

NicoleHanson — Thu, 15 Nov 2012 14:37:14 GMT

On way is to do a Service Area with generating LINES not Polygons. Make the break large, like 30 miles or so, and it'll show you where the disconnect is.

Re: Hierarchy Problem - No Solution Found

JaySandhu — Thu, 15 Nov 2012 14:57:24 GMT

You can do a couple of things:

Select only the streets for levels 1 to 3. Create a feature layer from the selection. Now symbolize each layer with different color and see if you can visually see some gaps between the lines

Use Nicole's suggestion, but first write out the selected level 1 to 3 lines to a new feature class, make a network on it and then run the service area for a large value with the Lines option (not polygons). Does the service area cover all the lines?

Jay Sandhu

Re: Hierarchy Problem - No Solution Found

RizwanShahid — Tue, 20 Nov 2012 16:31:19 GMT

Thanks Jay. It worked. Now the problem is to set up turn delays based on the original hierarchy values. I had 1 to 6 hierarchical values; I combined 1 to 4 as Primary Road, 5 as Secondary, and 6 as Local. Now I want to include turn delays based on original hierarchical values (1 to 6). Different delays from 1 to 2 left or right turn and different turn delay from 3 to 4 etc. Any suggestion how to efficiently do it?