topic Peculiar behaviour while conducting a location-allocation exercise in ArcGIS Network Analyst Questions

Peculiar behaviour while conducting a location-allocation exercise

MarkShymanski — Tue, 24 Jan 2012 12:23:00 GMT

This exercise is the precursor to a much larger project but I thought I'd start with a more manageable dataset and build from their.

I have a roughly 16 mile square with potentially 900 facilities and 990 demand points. I am using the location-allocation tool in NA with Problem Type: Maximize Coverage; Facilities to Choose: 18, Impedance Cutoff: 1800, Impedence Transformation: Power and Impedance Power: 1. The result I am getting is fairly sensible except for the unexpected clustering of two or three 'Chosen' facilities within each other's catchment. I am also getting demand counts with a huge range (from 8 to 97 in the case of 20 chosen facilities and 8 to 156 in my 18 facility option. I've had the data set tried on a different computer and it works as expected but when I do it on my machine (running XP proff. ArcGIS10 svpk 2) I get this weird behaviour.

Has anybody else had this experience? Any suggestions as to what I should do totroubleshoot/fix it? Any advice greatly appreciated!

Re: Peculiar behaviour while conducting a location-allocation exercise

JaySandhu — Tue, 24 Jan 2012 15:41:54 GMT

Do note that that Location-Allocation is not trying to balance all choosen facilities with the same amount of demand, so each facility can have a wide range of demand points assigned to it.

However, you should not get two different solutions on the same data/problem on two different machines.

If you are geting different behavior then it could be a difference in the underlying network dataset (restrictions, impedance, etc)
or the locations are not correct. By that I mean you may have loaded the locations using "network locations" instead of geometry when in fact the network locations have become stale. You could create a new Location-Allocation layer on your problem layer, re-load the locations making sure to check on the Use Geometry and not the Use Network Location Fields and re-solve.

If this does not solve the issue, then perhaps you can post a screen-shot of what you are getting.

Jay Sandhu

Re: Peculiar behaviour while conducting a location-allocation exercise

MarkShymanski — Mon, 30 Jan 2012 14:01:13 GMT

Thank you Jay for the reply. After much consultation with ESRI's excellant tech support it was determined that a re install of the software was required. Once that was done everything worked as planned.