calculate walk-time from a polygon?

[DanAllison]

I am using walk time calculation (Analysis: Use Proximity: Create Drive-time Areas)  in ArcGIS Online. What I want to do is calculate a 10-minute walk from a park boundary, but walk time only works with points. The parks I am using are of greatly varying size, so a centroid point may or may not accurately represent the park. I could also use a buffer with a distance equivalent to the walk time, but then it isn't following the street network. Can anyone suggest a solution? I have a personal user license for ArcGIS Pro and Online, so do not have access to the added value/cost analysis tools.

[DanPatterson_Retired]

weigh the potential walk time through your largest park versus your 10 minute threshold.  If it takes 10 minutes, for instance, then you will have to mark the entrances as origins and combine the resultant to get a bigger picture.  For smaller parks or parks with no defined entrance, the a centroid is probably all you can work with and you might have to adjust your time threshold(s) to reflect park size.

[MaxZeng]

You could potentially solve this in two ways:

1. If you have park entrance data, then you could calculate 10-minute walk time polygon from park entrances. 

2. If you don't have park entrance data, or your parks don't have defined entrances, then you could use Generate Points Along Lines tool to generate a set of points on your park boundary lines. After that you could calculate 10-minute walk time areas from those points. Since you are using ArcGIS Online create drive time area tool to calculate the polygon, and the tool charges credits by number of points, so you need to consider how many points to generate for each park (this can be done in the create points along lines tool). You will need to weigh the cost vs resolution of the result. 

[DanAllison]

Thank you, Dan and Max. For some of the larger parks and very linear parks (Sacramento River Parkway, for example), the parks can only be entered at certain points because they are surrounded by private lands, so points along a line won't give me the correct result. I guess I will have to manually create a point dataset of park entrances, which will slow me down. I don't think this information exists with the park agencies, and I've not had good luck asking them for GIS data in any case. Park boundaries are posted to open portals, but nothing more specific.