Mapping Travel Flows

[SarahGates]

I am working on a project mapping and analyzing travel flows for work between municipalities in the Greater Philadelphia Region. Does anyone have experience with using GIS to map flows of travel from one area to another at the municipal/town level? Also, does anyone know where I may look for data on work travel flows in this region?

Thank you!

[BenChaney]

Hi Sarah,

I don't have exact experience with what you're talking about, but I can point you to some resources.

First, I've used the Census Transportation Planning Products (CTPP) to get work travel flow data.  It's based on the American Community Survey data from 2006-2010 and compiled by AASHTO, a major transportation organization. The granularity will vary by region, but should be pretty good for Greater Philadelphia. Check it out here: AASHTO - CTPP - 5-Year Data‌

For GIS mapping of the travel flows, my first thought would be a flow map on a network diagram with line width based on flow volume.  I'm most familiar with these as a direct output of travel demand modeling programs, but you could likely create something similar based on custom data in GIS.  I don't have any examples off hand of travel volumes, but this is the style that I'm talking about: Flow map - Wikipedia, the free encyclopedia‌

I hope that's helpful as a starting place!  It's a topic I'm interested in too and would love to hear some other people's experience.

~Ben

[SarahGates]

Thank you very much Ben! I found the CTPP data to be very helpful! I am still working on the actual mapping of flows and I will let you know if I find a method that works well.

[MaraKaminowitz]

Ditto on the CTPP.  However if you are dealing with municipal-level data, you may want to check with your local state data center or planning department.  They may already have the data extracted from CTPP and stored in a user-friendly format.

As for depicting flow data, that question seems to torment a lot of people (like me).  Arrows are a popular choice but I have found creating them automatically in GIS leads to clunky results.  You can do a much nicer job with graphics software, but then you lose the connection to the live data unless you have a specialized software set-up.  What we have been doing is using a thematic map that centers on inflow or outflow to a particular area.  Here is an old example but it illustrates what I mean. http://www.baltometro.org/images/stories/BMC_CommuteShed.pdf‌

[MelindaMorang]

Hi.  I just learned about the new StreetLytics product from Citilabs, an Esri partner company.  They have extensive traffic flow and volume data for a bunch of large cities around the country.  It looks like Philadelphia is one of them.

StreetLytics by Citilabs‌

[SarahGates]

I just requested a free trial of StreetLytics, it looks like a very interesting collection of data and I am looking forward to see how they represent traffic flow data, thank you for introducing me to this site!