Network Analyst - Closest Facility Tool Discrepancies

Question

Using the closest facility tool, I've noticed that when I try to figure out the shortest distance between two nodes there are some discrepancies.  Case in point, I'm trying to connect nodes to several transit locations - trying to see which routes are closest to transit in the surrounding communities.  I have 10 transit stations (Facilities) and about 700 nodes (Incidents).  Some Incidents are not being routed to the closest Facility.  There's no hierarchy in my network dataset, it's just a bare bones one (just using TIGER files in which I ensured its topological accuracy and checked for dangling nodes).  Any thoughts would be greatly appreciated!  It's only happening a few times out of hundreds so it's not terrible but still a little puzzling.

JoeBorgione · Answer

Using the closest facility tool, I've noticed that when I try to figure out the shortest distance between two nodes there are some discrepancies.  Case in point, I'm trying to connect nodes to several transit locations - trying to see which routes are closest to transit in the surrounding communities.  I have 10 transit stations (Facilities) and about 700 nodes (Incidents).  Some Incidents are not being routed to the closest Facility.  There's no hierarchy in my network dataset, it's just a bare bones one (just using TIGER files in which I ensured its topological accuracy and checked for dangling nodes).  Any thoughts would be greatly appreciated!  It's only happening a few times out of hundreds so it's not terrible but still a little puzzling.

I'm just curious as to how you are sure that "Some Incidents are not being routed to the closest Facility" ?  What criteria are basing your solver upon? Distance only?  What are the units of your data and what are your units of distance that you are solving for?

If you are only seeing it in a few cases, you might isolate those cases and see if you do in fact have connectivity along the route you think it should be taking.  What I've done in cases like this is manually place stops along the route I like and see if it will solve along the way.