Roadway distance to polygon

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09-18-2017 04:30 PM
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New Contributor III

Hello. I need to map the roadway distance from a point to a polygon (or polygon to polygon). Is this possible in either ArcMap (preferred method - I work on this regularly) or qGIS? I know I can't add polygons as a location in Network Analyst so I'm not sure if it's possible. Thank you!

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MVP Esteemed Contributor

You could always Intersect your road (polyline) with the polygon to get the intersection point... then it would be a point-to-point analysis which NA can surely handle

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New Contributor III

Oh, interesting! So I'd just run the intersect tool with all of my roads (I'm working with California) and all of my polygons. Then the output would be points. And I would use those points as my location? Would the output be the central point in those polygons? 

P.S. Thanks for always answering my questions, Dan! 

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MVP Esteemed Contributor

If you look at intersect Lindsey, if you intersect a line with a polygon, you have to option to return points.  The points returned would be the boundary of the line/polygon intersection.

Now... you mention all of California with your roads... perhaps you might want to step back and explain exactly what it is you are intending to do?  The centroid of a polygon may not appear on, or near a road, so those would be relatively useless.  If you could scope out the details a bit more, then I sure some suggestions will follow.

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New Contributor III

Good idea. I have a list of 1200+ polygons and a separate list of 400+ points located all throughout California. I need the roadway distance from those 400 points to the 1200 polygons. So then how would I pick which point (created by the intersect tool using the roads/polygons) for it to go to? Ideally, I'd want the closest part of the polygon to the original point. Does that make sense? Not sure how I'd pick each point for it to go to, especially since it's such a large dataset. 

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