# Network Analyst

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08-26-2016 12:30 AM
New Contributor

Good morning and happy friday,

following problem: I've created with the network analyst drive time zones (15 min break) from 20 points. The goal is to find the centroid of all drive time polygons based on the road network and not the bee line. I've to find a new location, which is in in middle of all drive time polygons in relation to the route network.

Do you have any idea how to solve the problem?

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9 Replies
MVP Emeritus

image?  still not quite getting what you have... whether the drive times are discrete or overlapping and what central point you are looking for

New Contributor

The picture shows a city with a route layer. I created a drive time zone (15 min break, yellow color) at any point (red color) around. The result is one shapefile with the drive time polygons of each point.

The goal of my work is to find a location, from which i minimize the drive time to each point. That's why I asked for the central point. If I'm right, you can calculate the central point of all polygons (one big area within all drive time zones of all points), but the result is a middle point based on the bee line. I want to creat the central point based on the route layer. I hope you understand my problem now.

MVP Emeritus

I would begin with the multiple facilities analysis with allowing for overlapping polygons ... way down near the bottom of this link Service area analysis—Help | ArcGIS for Desktop

that would be the starting point... we can move on from there

MVP Alum

I'm not sure I understand the relevance of the polygons you've already created in relation to the stated goal of finding a central point that minimizes the drive time to each point using the network.  I feel almost like something is missing here.  Is there a constraint in analyzing the central point imposed by the polygons you've already created?

Chris Donohue, GISP

MVP Emeritus

Chris, I think Felix is trying to find the best location to locate 'something' but the drive times from the existing is important as well.  It is kind of like a closest facility but you don't know where the incident is yet.  I think... as of my reading... that an overlay without dissolving might reveal if there is an area common to all that meet the threshold distance.  The problem appears that the analysis dissolved the polygons making an amorphous mass and potentially hiding the area of potential... don't know of a better way of wording it

MVP Alum

I was guessing the analysis question was more along the lines of finding a central depot for a supply business.  The points represent the several supply business locations, then the original poster wants to find the best location on the road network that would most effectively service all those supply business locations for a Central Depot/Warehouse.  In this case the Service Areas polygons already created would not be relevant.  But again, this is just a guess.

Chris Donohue, GISP

New Contributor

Good morning Chris,

on the whole you got my problem. I think it's better if I'll give you a breef introduction to my study.

I work in the wind energy sector. My goal is to find two or three new stores, from which the worker can reach as many windturbines as possible in a shortest track to minimize the drive time. The stores have to be located in the middle and south of Germany. I need the drive time zones to produce areas with a high concentration of wind turbines. So, if I creat  for example a drive time zone of three wind turbines, there will be an area, in which the three zones overlap each other. I want to find exactly these zone, where as many drive time zones as possible overlap each other. How can I get these overlapping areas?

Kind regards,

Felix

MVP Alum

A suggestion - I'm not sure given your data, but it may be that you could use the Location-Allocation (Network Analyst) process for this instead of using the 15 minute polygons that were already developed.  However, I believe it requires point locations of potential store locations ("Facilities") besides the locations you want to serve ("Demand Points"), so that could derail things if that information is not available.

Chris Donohue, GISP

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