Latest Contributions by MelindaMorang

1. What tool or python methods are you using to programmatically create your line segments?  This is a bit outside my area of expertise, but I'm guessing there's some kind of environment settings for the tool you could put into place.  Or perhaps the Snap tool would help? ArcGIS Help (10.2, 10.2.1, and 10.2.2) If you describe your workflow a bit more thoroughly, I can try to help more. 2. Ah, interesting.  As you have discovered, you can't delete the feature class.  You could, however, delete all the features in the feature class (use Delete Rows or an update cursor) and then add the new features to the existing feature class.  Again, this might depend on how you're creating the features. ... View more

You can just set the U-Turn policy of your Network Analysis layer to "Not Allowed".  This is an NA layer setting rather than something you build into your network dataset. U-turn policies—Help | ArcGIS for Desktop ... View more

(Thanks, Chris.) Hi Charlotte J.  The previous answers have summarized the likely problem.  For some reason, your points are being located on network edges that are non-traversable.  Edges are non-traversable either because they are restricted because of a restriction, a barrier, or a negative impedance value (which the solver interprets as inaccessible). Normally, the first thing I would suggest you do is to check on the "Exclude restricted portions of the network" button in the NA layer properties "Network locations" page before you load locations.  This way, if an edge is restricted, the point won't get located there but will instead get located on the next-closest non-restricted edge.  This works great for restrictions and for existing barriers.  I'm not sure how you've constructed your 0mph edges, so I'm not sure if Add Locations will be able to determine that these edges are restricted or if it doesn't become apparent until solve time.  At any rate, this is the first thing I would try. To make your network a little more robust, I would create a restriction attribute that you can assign to all the non-car-traversable edges (like your bridlepaths) rather than using 0mph speed profiles.  That seems like a kind of odd way to do it when restriction attributes are specifically designed to do exactly this. Note for everyone: "Snap to network" does not impact whether or not points get "located" on the network".  No matter how you set this, the points are always "located" on a particular network edge (or junction), and that network location will be used as the starting point for the analysis.  "Snap to network" just moves the visible location of the facility/stop/incident to the network location.  Otherwise, it will show up in the original location of the input, even though it's the network location that's being used in the analysis.  To summarize: "Snap to network" will not change anything in the way your analysis runs and will not fix any of the problems Charlotte J is experiencing here. ... View more

No, this isn't going to work.  When you add a location to an NA layer (for instance, you add your park centroid as a Facility in a Service Area layer), the location "locates" on the closest network edge.  Although the geographical location of the point remains the same (the center of the park), the network analysis uses the network location of the point when considering how to route to it.  So if you erase all the network edges inside the park, the centroid will snap to the closest remaining edge, and the service area will build out from there.  If the park is large and has many entrances, this will be pretty inaccurate.  It would be more accurate to place a point at every park entrance and calculate service areas around all these points. ... View more

That is a possibility, so you just need to experiment a little with the buffer distance until you get what you're looking for.  Or if you have one particularly problematic park, manually edit in some entrance points. ... View more

That doesn't always work well, particularly if your park is very large and rectangular.  Then it will have only 4 vertices at the corners. ... View more

Do you have your street data (ie, you're not working in ArcGIS Online)?  If so, try this: - Add the network dataset's junction feature class to the map.  This is the automatically-generated feature class of network junctions (like intersections) that lives in the same feature dataset as the network. - Do a Select by Location and select all junctions within some very small distance of the park boundaries. - Export the selected junctions to a new feature class.  These selected junctions can serve as a sort of proxy for park entrances.  You can use them as input for your network analysis. ... View more

No, I don't think it would be possible to calculate the max width during the solve.  Since you don't know what road segments were used until the solve is completed anyway, it would still have to involve some kind of post-processing.  The most seamless way to do this would probably be to build a model or a script that both solves the analysis and calculates the width statistics on the results immediately.  Then you just run that model/script to get your results rather than running the Solve tool. ... View more

Okay, so which network is giving you the solution you expect?  2D or 3D?  I wasn't quite sure from your screenshot which is which. Regardless, it appears that the two network datasets don't have the same cost attributes.  The one with the "Add" button not grayed out looks like it has several attributes that make sense.  "speed" is a descriptor which is probably used to calculate the "Time" attribute, which has units of minutes. The other network (the one where the Add button is grayed out for some reason) seems to have an attribute called speed with units of minutes.  That doesn't make sense to me.  Assuming this is the network you set up yourself, then I think you just didn't set up your cost attributes correctly.  Instead of a 5-minute travel time, your service area is solving for 5 some-nonsensical-units. Since you're new to Network Analyst, I encourage you to work through the Network Analyst tutorials.  Hopefully these will clarify how to set up cost attributes and use them in an analysis. ArcGIS Help (10.2, 10.2.1, and 10.2.2) I recommend starting with Exercise 1 and then doing Exercise 5.  Those will be the most relevant for your workflow. ... View more

[Chris, I get automatic notification of all new Network Analyst posts even if my name isn't tagged, but thanks for drawing my attention to this anyway.] Hi James.  What you're describing should work.  When the SA lines are set to Overlapping, you should get duplicates of lines that are traversed more than once if they are reachable from different facilities. For instance, in the simple test case below, the middle area is reachable by both facilities, and the highlighted line is in the Lines output twice, each one marked with a distinct FacilityID. The question is why you aren't getting this expected answer. Do you have more than one Service Area layer in your map?  Are you perhaps adjusting and solving the wrong one and then looking at the results for a different one?  Sometimes that happens if you forget to switch the drop-down layer selector in the Network Analyst window. Are you sure that the reachable area from your two fire stations actually overlaps? If it's not any of that, then I don't know what the problem would be.  Are you able to share your data?  If you could wrap up your network and your layer (with all its settings) in a map package and share it, I could take a look at it. ... View more

For your polygons to be meaningful, it seems like you would need to include some street data.  Pedestrians can leave the bus and walk down a side street, for instance. I really can't tell why your service areas look strange without looking at the data.  Would you be able to post it somewhere? ... View more

Are you using trim for your polygons?  If not, try turning on trim (in the Service Area layer settings) and see if the spikes go away. Are the lines shown in the picture the only lines you have in your network, or do you also have a streets feature class that isn't shown?  If you have streets that aren't shown, perhaps the spikes are due to a connectivity problem with your streets. ~Melinda ... View more