topic Re: service area buffer not functioning properly in ArcGIS Network Analyst Questions

service area buffer not functioning properly

KevinJohnson14 — Fri, 04 May 2018 16:29:55 GMT

I am encountering issues for the Service Area function in Network Analysis in ArcMap 10.6. Here is a summary of my steps:

- I have obtained the pertinent shapefiles for my analysis. Streets, hospitals and converted them into a State Coordinate Plane map projection. (They were originally a GSC_N_American_1983 and decimal degrees where shown in the lower right corner in ArcMap)

- I created a new geodatabase file (gdb) and imported associated layers in the new map projection.

- In ArcCatalog, I right clicked on the projected streets shapefile (not in the gdb) and selected New Network Dataset. I created a new Network Dataset and generally leave the default settings. For Length, I changed the measured units from Meters to Miles.

- In Network Analysis, I selected New Service Area and select the hospitals_projected shapefile as the facilities in Load Locations. The locations display as Located under the Facilities layer. I have tried different distances for Location Position/Use Geometry, and this is the area where I am having my issue. My goal was to run this for 5 miles. It works after selecting OK in the Load Locations window and select the Solve icon, but each time I run the Service Area it creates only a 1 mile road buffer around each facility.

I did notice that I should calculate geometry for the streets shapefile, and I went back to calculate this while deleting the files in the gdb and basically starting all over again. Should I use the hospitals shapefile used in the Service Area in my gdb or the one that I projected? Lastly, it appears the hospitals shapefile points were all moved on the road network, but is there a way to verify this?

Re: service area buffer not functioning properly

DanPatterson_Retired — Fri, 04 May 2018 16:44:53 GMT

Use projected data for everything since it removes any concerns about what the coordinate systems of the files are in

Re: service area buffer not functioning properly

MelindaMorang — Fri, 04 May 2018 18:26:52 GMT

How do you know the Service Area is only 1 mile from your facilities? Is it exactly 1 mile, or just approximately. Might be helpful for you to post a screenshot.

Since you said you left most of the network dataset settings as default, I'm guessing there's a problem with the way your Length attribute is configured. You should open up the Evaluators dialog for that attribute and make sure it's configured in a sensible way. See Types of evaluators used by a network—Help | ArcGIS Desktop to understand more about what evaluators are and how they should be configured depending on your desired outcome.

The other possibility is that your network's connectivity isn't set up appropriately for your data. You might need to switch your connectivity policy from End Point to Any Vertex. See Understanding connectivity—Help | ArcGIS Desktop

Re: service area buffer not functioning properly

KevinJohnson14 — Sat, 05 May 2018 06:56:27 GMT

Here is a screenshot of one of my service area that I measured to be only one mile.

I went back to create a New Network Dataset and modified the connectivity policy from end point to any vertex.

Lastly, I did modify the Units from Meters to Miles.

Should the Data Type be Double?

Re: service area buffer not functioning properly

KevinJohnson14 — Sat, 05 May 2018 07:00:31 GMT

Here is the Attributes of Length. I had to modify the Units from Meters to Miles.

Re: service area buffer not functioning properly

KevinJohnson14 — Sat, 05 May 2018 07:04:50 GMT

Lastly, here is the output of the 1 mile buffer, which I did not request.

Any advice?

Re: service area buffer not functioning properly

DanPatterson_Retired — Sun, 06 May 2018 00:17:42 GMT

attachments seem to be missing

Re: service area buffer not functioning properly

MelindaMorang — Mon, 07 May 2018 15:38:39 GMT

I can't see the screenshots, either. Only the first one with the connectivity policy.