Network Analysis/Equity Analysis of access to transportation

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05-28-2013 01:27 PM
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New Contributor
Hello GIS gurus,

I am attempting to run an equity analysis of access to public transportation for the various racial/ethnic groups represented in U.S. census data within my area. I have a street network dataset for the area, including the bus stops/stations as facilities within the dataset and I have attached the relevant census data to the census blocks within the area.

The question I have is how to best calculate the numbers of each race/ethnicity/religion/etc that have access to each bus stop. I am a bit out of my depth with this, so any advice I can get would be appreciated...Im looking for any tools, methods or similar existing projects that I could draw some ideas from and get my project moving again as well as clarify future questions.

Thanks!
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Esri Regular Contributor
You can use two different approaches:

1. You can assume that the census geography can be represented by its centroids. In that case you can run a Closest Facility analysis from the bus stops to see how many such census centroids are within your analysis distance. You can then sum up the racial profiles from the census points reached

2. You can assume that for each census geography polygon everyone lives in a uniform distribution. You can then generate service area polygons from your bus stops for the appropriate distance (generalized option, make sure hierarchy is off) and then use these resulting polygons to intersect with the census geography polygon. Then given the percentage of the polygon contained in the service area (use a ratio of new area to original area) you can summarize the racial mix.

Jay Sandhu
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Thank You! That certainly helped me to get things rolling again...Ive played a bit with both the methods that you recommended and have some interesting new layers for analysis. The latter seems more along the lines of what I am looking to do, however I am having some trouble with it...Creating the service areas is simple enough but the intersect tool is uncooperative and wont finish calculating at the moment. I attempted to use a spatial join instead and have created that layer with no problems, but the census data did not carry over so I'm still unsure how to summarize the statistics in such a way that I can present them via a cartographic product.

I know I am communicating my issues fairly poorly, thanks for your patience and help!
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Esri Regular Contributor
You can look into using the Tabulate Intersections tool:
http://resources.arcgis.com/en/help/main/10.1/index.html#//000800000044000000

Jay Sandhu
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Esri Regular Contributor
Hello Saren.  Were you ever able to complete your analysis?  It might be too late to be relevant now, but you might find this tool helpful for your study: http://www.arcgis.com/home/item.html?id=42e57c5ff9a0497f831f4fced087b9b0
This tool allows you to create buffers around your bus stops and weight them by the number of transit trips that actually serve the stops.
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