Network analyst - service area: defining individual distances for each location

IreneWeinberger

Hello everyone,

I have something like 10'000 locations on a Network. For all locations, I need now to get another location along the network with a specific individual pre-defined distance (I am working with ecological data and try to implement so called step-selection function on a species that moves on a network)

My shapefile looks like that:

Location (x/y)     Distance

A                         56

B                         360

C                         2350

D                         24

Now, I think I can use the service area in Network Analyst to get the polygons or lines to get the new locations (lets say A1-Ax, which have a distance of 56 m from A, B1-Bx with a distance of 360m from B etc.). However, I am at a loss how I can automatically calculate the new locations: Can I set the parameter "Distance" somewhere so that for every location the individual distance will be taken? How do I do that? And what is the best approach to get the locations (is it easier to get it from the polygons or from lines? And how to retreive them from there?)

Thanks a lot!

Melinda Morang

Yes, it is possible to set an individual break value for each Facility in your Service Area.  The Facilities sublayer has fields named Breaks_[name of impedance attribute on your network].  So if your impedance attribute was called Distance, there would be a field called "Breaks_Distance".  If you enter in a value for a particular facility in Breaks_Distance, this will override the default break value you set in the Service Area layer properties.  Any facility that has no value in Breaks_Distance just uses the default break value.

To see the above described in the ArcGIS documentation, check out this page: ArcGIS Help (10.2, 10.2.1, and 10.2.2).  Scroll down to the table showing input and output fields under "Facility Properties".

Since it sounds like you have a field in your input data called Distance, you can just use field mapping when you Load Locations to map the values in your distance field to the Breaks_Distance field in the Facilities sublayer.

Some information about field mapping is included on this page in the ArcGIS documentation: ArcGIS Help (10.2, 10.2.1, and 10.2.2).