Hi Natalie. Let me try to address each of your problems individually below.
Hierarchy
Hierarchy is a way of speeding up lengthy, long-distance route calculations by ignoring small local roads and preferring highways. It is not fully guaranteed to give the true shortest path, but it does a good job most of the time. If you solve without hierarchy, all the roads will be searched until the true shortest path is found. Consequently, your observation that some of the routes created were obviously not the shortest path when you were not using hierarchy makes me think that your network has some connectivity problems. If you're not using hierarchy, the Closest Facility solver will always return the shortest path through the network. If the shortest path looks wrong, it's probably because the network has some problems.
Network dataset problems
Here are a few common network dataset problems that cause incorrect results:
- Your impedance attribute isn't set up correctly, so all roads have 0 impedance (then it doesn't even matter what roads are used in the route because it costs nothing to travel across any of them).
- Your road features don't actually touch at intersection points. Maybe when they were digitized, you didn't have snapping turned on, and the road endpoints just don't coincide, so it's not possible to travel across intersections.
- Your road features touch, but the points of intersection don't have a vertex (if you have an Any Vertex connectivity policy) or an endpoint (if you have an End Point connectivity policy). In this case, the roads appear connected but aren't actually logically connected in the network.
This documentation page provides further information: ArcGIS Help (10.2, 10.2.1, and 10.2.2)
Solve not creating a path to all facilities
You definitely need to set "Facilities to Find" equal to the number of facilities you have if you want a route to be generated to all of them for each Incident. If some routes still aren't being generated, it's possible that no route was found in the network (which should generate a warning message). That would be another symptom of a network dataset problem.
Other things to think about
- If you're having trouble with your network dataset, and if you don't need to use your own street data (for instance, you have your own forest roads that you've added), you could use our online Closest Facility service. You would be charged credits from your ArcGIS Online account, but it would save you the trouble of creating and managing your own network dataset. You can connect to the online services through ArcMap as described here: ArcGIS Help (10.2, 10.2.1, and 10.2.2)
- If you just need the travel time or distance between your points and not the actual routes taken, you should use the OD Cost Matrix tool instead of Closest Facility. It will run much faster, and it defaults to finding all OD pairs.
