Routing without circuits (minimum spanning tree)

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05-19-2010 06:38 AM
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New Contributor
Hi,

my question is, how can I do a routing WITHOUT circuits/ circles? Like a minimum spanning tree.

I have a network with edges and junctions (based on streets). And the edges have a length attribute. And now I want to add a central station (junction) and some consumers (junctions) along this network. Then I want to route from the central station to all consumers in the shortest way, BUT the routing is not allowed to have any circuits!

Thank you very much in advance.
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Esri Regular Contributor
Given your needs, I am not sure if you need a minimum spanning tree. You have a central station and consumers and want you want to route from the station to all consumers. Can you be more specific? Is this one route that starts at the station and visits the consumers or is one route per consumer from the station.
If you want to do the first, that is, start at the station and visit the consumers in the best possible way, then the solution is called a travelling salesman problem. You can use the Route solver (in Network Analyst), load you station as the first stop, your consumers as next set of stops and then bring up the route layer properties and on the Analysis tab, Click ON the "Reorder stops to find optimal Route" and un-check the preserve last stop. Solve.
If you need to do the second option, i.e. paths from station to consumers, use the Closest Facility Solver, load your station as the facility and the consumers as incidents and solve. You will get one path per consumer to station. You can set the travel direction from the facility or to the facility as needed.
Jay Sandhu
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First of all, thank you for your quick answer.

I will describe my issue more precisely, I want to build up a utility network (water tubes for heating), there are a heating system (central station) and consumers. I have to find the best (shortest) way to include all consumers into one network based on the heating system (the order does not matter) to get the base for creating a geometric network . And because of technical specifics, the network is not allowed to have circuits. I think I have already tried out all routing possibilities and the Route solver is useless, because I can not define to neglect circuits!
So the "Closest Facility" Routing is probably the best one in my case. But the problem is that the result is not a network! For each consumer there is one Route to the heating system and that is not what I want. So in my opinion I have to do a "minimum spanning tree routing" to get what I want, but I don't know how to do this with ArcGIS.

So my questions are:

a. If I do a "Closest Facility" Routing, can I am as safe as houses that there are not any circuits in my Routing?!
    And how can I create a network with this result?
b. Is it possible to do this like a minimum spanning tree? And if yes HOW?

Thank you very much in advance.

Martin Miksche
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Esri Regular Contributor
Martin,
Given that you are trying to set up a distribution system, a minimum spanning tree would be the best solution.
You can always export the output routes of the closest facility solver into a feature class, use topology to create vertices where the lines cross each other and then build a network dataset on that with anypoint connectivity. Perhaps that might give you what you need.
There is no MST solution in the core ArcGIS product, but you could write your own. Perhaps this user contributed script could help as well: http://arcscripts.esri.com/details.asp?dbid=15121
Regards,
Jay Sandhu
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