topic Re: Network Analyst -- No route between two locations in ArcGIS Network Analyst Questions

Network Analyst -- No route between two locations

JeremyScott — Tue, 26 May 2020 16:55:47 GMT

I am attempting to create routes between bus stops using Network Analyst. In some cases, I get an error message that says there is no route between two locations. I have played around with the topology in case there were issues there (increasing xy tolerance to 1ft) and I have also set the directionality for all segments to be bidirectional. Both of these were in an attempt to get a temporary solution. I am not exactly sure what to look for in determining what the issue is. I have attached a screenshot showing the two points that cannot be routed along with the error message.

Re: Network Analyst -- No route between two locations

MelindaMorang — Tue, 26 May 2020 17:02:39 GMT

My guess is that something is disconnected in your network. Try using the Network Identify tool on the Network Analyst toolbar. With this tool activated, you can click on a road segment, and it will show you which other network edges and junctions it's connected to. You can use this to diagnose connectivity problems. The tool will also tell you the value of various restrictions and impedance attributes, so you should check those and make sure they are correct as well.

If you make any edits to your network dataset, don't forget to run Build Network before running an analysis

Re: Network Analyst -- No route between two locations

JeremyScott — Tue, 26 May 2020 17:58:11 GMT

Hey, Melinda.

Thank you for getting back to me. I have used the Network Identify tool on

all segments between the two stops and don't see anything that appears to

be out of order (I am not really sure what I am looking for). Any other

suggestions? I was able to connect stop 25 with stop 27 by allowing the

reordering of stops (I can't do this in the final analysis) and that

worked, but still left out stop 26.

Sincerely,

Jeremy

Re: Network Analyst -- No route between two locations

MelindaMorang — Tue, 26 May 2020 18:09:33 GMT

It still smells like a connectivity issue to me. Here is some conceptual documentation explaining the various types of connectivity in case you want to dig into it: Understanding connectivity—Help | Documentation

If you are able to share your data (both network dataset and Route layer), I could take a look.

Re: Network Analyst -- No route between two locations

JaySandhu — Wed, 27 May 2020 16:27:55 GMT

You can also do a service area (with the lines option, not polygons) from one of your stops and see if you can reach the second stop. It might show the connectivity problem area.

Jay Sandhu

Re: Network Analyst -- No route between two locations

JeremyScott — Tue, 02 Jun 2020 18:28:25 GMT

Jay,

How do I fix this issue on a global level? I was able to fix the issue with

the previous example, but now running into it in other places. As far as I

can tell, there don't appear to be any network issues (I disconnected and

reconnected each of the segments at the intersection in question). The

screenshot below shows the issue for the road segments in light blue.

Thanks,

Jeremy

Re: Network Analyst -- No route between two locations

JaySandhu — Tue, 02 Jun 2020 18:51:27 GMT

The screen shot in question shows the blue lines connecting to the purple lines at one location. Is the purple line split at that location if you are using End point connectivity? If it is not split, is there a vertex there for the blue lines to connect IF use Any Vertex connectivity? If you do not have it split AND you do not have a vertex on it for any vertex connectivity then you may want to run the GP tool Integrate to create those vertices. If you do use Integrate, make sure you use it on a copy of the data as it will modify the data.

Integrate—Data Management toolbox | Documentation

Jay Sandhu

Re: Network Analyst -- No route between two locations

JeremyScott — Tue, 02 Jun 2020 19:09:59 GMT

Jay,

Thank you for responding. The purple line does split where the blue line

meets. At that intersection, there are three separate lines meeting at the

same vertex. So, it seems there is an intersection there and the

directionality of all segments should allow a traversal from the blue line

to the purple line.

Thanks,

Jeremy

Re: Network Analyst -- No route between two locations

JaySandhu — Tue, 02 Jun 2020 19:45:47 GMT

Can you do a service area lines from a location on the blue lines and does it get stopped at the junction where it connects to purple lines? If yes, then there is some issue in the connectivity there. Perhaps the blue line is not snapped to the purple lines. Or it could be a restriction or negative attribute value that prevents the path.

It is hard to "debug" without looking at the data. If the data is small (or make a subset), perhaps you can package up the data with a couple of locations that do not route and send/post it.

Jay Sandhu

Re: Network Analyst -- No route between two locations

JeremyScott — Tue, 02 Jun 2020 21:02:11 GMT

Jay,

Here is the network dataset as well as a subset of the stop locations. The

two stop locations I know are causing problems are OBJECTID 49 and 52. When

I add the Stop Locations, the stop sequence field is defined as STOP SEQ

and the Route Name field I use us RUN BEGIN TIME. This should give you 4

routes, of which only two actually have a solution.

I really appreciate any help you may be able to provide. Let me know if you

have any questions or need anything else.

Sincerely,

Jeremy

Re: Network Analyst -- No route between two locations

JaySandhu — Tue, 02 Jun 2020 21:54:20 GMT

Jeremy,

Looking at the data explains the issue. Your street line data is 3D! So even though the X,Y may be the same, the Z values are not. For example, the three lines around bus stop feature 20 that do not connect have the following vertices:

15411, 2011544.876, 787417.068, 247.212
15521, 2011544.876, 787417.068, 247.212
5530, 2011544.876, 787417.068, 244.100

Even though the X and Y are the same, the Z values of one of them, 244.1 does not match the 247.212 of the others. Visually:

You could either fix the data at the places the z's do not match or drop the z's and rebuild the network

Jay Sandhu

Re: Network Analyst -- No route between two locations

JaySandhu — Tue, 02 Jun 2020 22:15:35 GMT

The streets around junction 49 are not connected to anything:

I did a service area lines for 30,000 feet around junction 52 and say many disconnected areas: Purple is the reached service area lines over the blue streets. I put yellow circle around some of the disconnected edges.

Jay Sandhu

Re: Network Analyst -- No route between two locations

JeremyScott — Tue, 02 Jun 2020 22:32:47 GMT

Jay,

I meant the OBJECTID off the bus route layer, not the junctions layer. I

know there are a few instances of 'islands' due to cutting the network

dataset to our service area. I may have to expand to ensure this does not

happen with the final product. However, catching the differences in the

z-coordinate was the difference (I am assuming you manually calculated this

or was there another step you did to find this discrepancy?). This was not

something that I would have thought and probably should have just removed

it from the network dataset to start with since I wasn't worried about

elevation. After removing elevation from the network dataset, I was able to

route 1031 bus routes (all but 9). I will dig deeper into these 9, but I

have a feeling they will be based on the issue you raised about the

'islands'.

Thank you so much for your assistance!

Jeremy

Re: Network Analyst -- No route between two locations

JaySandhu — Tue, 02 Jun 2020 22:39:05 GMT

I meant to say ObjectID not junctionID. Those 49 and 52 were the ones you mentioned, so I was using them in the examples. Glad that removing the 3D has given you most of the routes. The rest I expect are going to be disconnected portions of the network. Let me know if you are not able to find the root cause for them.

As far as the 3D, I just looked at the line feature class properties and realized it was Z enabled, so used the Editor to examine the 3D sketch properties and see the 3D vertices.

Regards,

Jay Sandhu