How to produce drive time polygons from polygon edge? (Network Analyst)

[AmyBonnie]

Hi all. I am creating a map showing food desert locations with Oxfordshire within ArcMap using the network analyst tool. I have a polygon of Oxfordshire and point data showing the location of large supermarkets across the UK. I also have OS road data with time of travel calculated. I want to be able to determine which of large supermarket points are within 25 minutes of the edge of the Oxfordshire boundary, so I can remove those not of interest to my study. Not sure what the best way of doing this is, apologies if my explanation is not clear. Any thoughts would be greatly appreciated.

[JaySandhu]

Since you are interested in 25 minutes of a polygon boundary, you will need to convert that into "points" as network analysis works on point locations on a road network. So use the GP tool Feature To Line to convert the polygon to a line feature class. Then use the GP tool Intersect and overlay the polygon line with the street lines making sure the output type is Points. This will create points at all locations the polygon intersects the streets. Now you can use the Origin Destination Cost Matrix solver and load these intersection points as Origins and your super market points as Destinations. Set the Cutoff to 25 minutes and solve. It will find all the super market points within 25 minutes. 

Jay Sandhu