topic Re: DriveTime mapping issue in ArcGIS Online Questions

DriveTime mapping issue

DanAllison — Thu, 13 Dec 2018 19:32:55 GMT

I'm using ArcGIS Online to create DriveTime walking time maps. Most of them look reasonable, but one is not correct. The result is the feature layer at https://allisondan.maps.arcgis.com/home/item.html?id=0d1b0526de694658b657e7c50aae93a1 . The darker area is the walk 20 minute outline, using an address search point, while the lighter area is the walk 20 minute outline, using an uploaded point. The locations are the same - you can see that they are coincident on the map, the the address analysis is clearly incorrect while the uploaded point analysis appears reasonable. Any ideas?

Re: DriveTime mapping issue

DeeleshMandloi — Thu, 13 Dec 2018 19:54:29 GMT

Hi Dan,

If I click on the link to open the web map, it asks me to sign into your ArcGIS Online organization. In order for me to look at the web map, can you make sure your web map is shared with "everyone"?

Thanks

Deelesh

Re: DriveTime mapping issue

DanAllison — Thu, 13 Dec 2018 21:43:19 GMT

Done. I’m new to ArcGIS Online, have been using ArcGIS Pro so I forget about things.

Dan Allison

Re: DriveTime mapping issue

DeeleshMandloi — Thu, 13 Dec 2018 22:49:13 GMT

Hi Dan,

I am still getting prompted for credentials when I click the web map link.

Thanks

Deelesh

Re: DriveTime mapping issue

DanAllison — Thu, 13 Dec 2018 23:01:56 GMT

Hmm. It says it is shared with everyone. How about this short URL?

https://arcg.is/1XP098

Dan Allison

Re: DriveTime mapping issue

DeeleshMandloi — Tue, 18 Dec 2018 22:58:19 GMT

I was finally able to access the webmap and that allowed me to determine why you were getting different results.

The two walk time polygons are created from a slightly different starting point. For any given point, the tool needs to find the point that is closest to the street network, and then the tool calculates how far it can travel in 20 minutes from the starting point on the street.

For your analysis, because the two starting points are slightly different, they end up being located on different portions of the street network and so produce different results.

In the screenshot below one of the polygons is created from the magenta colored point which ends up being located on Villa Oak Dr (since that is the closest location from that point). The green colored point ends up being located on the walking path in the park.

The green colored point is able to travel a lot less number of streets in 20 minutes as compared to the magenta colored point resulting in different walk time polygons.

Hope this helps

Deelesh

Re: DriveTime mapping issue

DanAllison — Tue, 18 Dec 2018 23:04:47 GMT

Thank you! I understand what you are saying. The ironic thing is that I got the green point from an address search in ArcGIS online, which is for a school that sits on Villa Oak, while the magenta point is from my GPS mapping app, Motion-X GPS. I’ll need to re-create my origin points as the front door of the school.