Distance Tool -- Insane Difference Between "DistanceMiles" & "DriveDistanceMiles"

I'm working on a project to calculate various point distances from the Florence disaster area. I'm noticing some very strange issues in my output.

When I run the distance tool comparing the centroid of 28206 (Charlotte NC) against a polygon of the disaster area, I get a result showing:

DistanceMiles - 33.7

Drivetime 243

DriveDistance 241.56

I'm also using TomTom Peak

I understand the drive distance might be a little longer, but this seems absurd.

spatial miles issue.yxzp

Spatial Analysis

Accepted answers

TravisR

@Inactive User

So the drive time and drive distance are fine. The issue is the straight line distance being calculated due to the tool configuration. With the way you have the distance tool set up - you're measuring two different things.

Start Point in Charlotte to the centroid of the disaster area via drive time/drive distance.
Start point in Charlotte to the nearest edge of the disaster area via straight line.

Notice that only the drive time/drive distance option mentions centroid based calculations.

It may seem a bit unintuitive, but the way the Distance Tool works when measuring straight line distance from a Point-to-Polygon (and Point-to-Line) is to use the nearest edge.

https://help.alteryx.com/2018.3/Distance.htm

If you want to calculate the straight line distance and the drive time/drive distance to the centroid of the polygon - you'll need to use a spatial info tool to generate the centroid point first and then set that as your destination point.

All comments

BenMoss

What does Google maps say for the drive time distance? Might be worth
looking at and sense checking.

TravisR

Hi @Inactive User

Edit: Got the workflow to open and am investigating.

TravisR

@Inactive User

Start Point in Charlotte to the centroid of the disaster area via drive time/drive distance.
Start point in Charlotte to the nearest edge of the disaster area via straight line.

Notice that only the drive time/drive distance option mentions centroid based calculations.

It may seem a bit unintuitive, but the way the Distance Tool works when measuring straight line distance from a Point-to-Polygon (and Point-to-Line) is to use the nearest edge.

https://help.alteryx.com/2018.3/Distance.htm

unknown

Thanks Travis -- Ha, I need to read a little more carefully.

But, I'm looking for drivetime distance to the nearest edge of the polygon, not the centroid...is that an option?

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