David Levinson, Andrew Owen and their team at the University of Minnesota have recently created the Accessibility Observatory. If you're interested in the topic, you may read a nice piece written by Emily Badger for TAC.
One of the greatest aspects of this project is about the data sources and methods they use for accessibility evaluation. Instead of relying on traditional household travel surveys, they combine open source data from OpenStreetMap (OSM) and from General Transit Feed Specification (GTFS), developed by Google. With this sort of data it is possible to analyze jointly the public transport system as a whole (routes, stops, and schedules) plus pedestrian routes and walking times. There is a more detailed explanation of how it works here.
I've bee thinking a lot about this 'empirical strategy' since I'm planning to dedicate part of my PhD to research socio-spatial inequalities in the distribution of accessibility. The more I think about this, the more I become a passionate skeptic, more passionate than skeptic.
To be honest, I believe that these data/methods are probably not going to revolutionize accessibility research in transport studies. However, this new 'empirical strategy' allows us to expand accessibility analysis so as to incorporate hundreds of cities where no travel survey has been undertaken. It also provides a tool with great potential to compare accessibility levels across space and time and to assess how certain modifications in the public transport system can affect accessibility levels. Not to mention the research questions you could address by combining these data/methods with Census data.
By the way, the use of GTFS in accessibility analysis is quite new. I have found a few applications that have been using GTFS since 2010 but none seems to be as advanced the Accessibility Observatory at Minnesota. Here is a list with some of those other initiatives:
- Stefan Wehrmeyer started in 2010 a project called mapnificent. Today it has perhaps the most comprehensive collection of cities so far.
- Comercial initiatives by Trulia in the US and by Mapumental in the UK.
- In 2011, Brookings Institution published the report 'Missed Opportunity - Transit and Jobs in Metropolitan America' analysing job accessibility based on GTFS for 100 metropolitan areas in the US.
- Renato Vieira and Haddad (2012) proposed a similar approach to build an accessibility index to São Paulo.
In 2013 we saw many more initiatives:
- Yuval Hadas published a paper in the JTG: Assessing public transport systems connectivity based on Google Transit data
- WNYC came up with this map of Transit times in NYC
- Andrew Hardin has also created his version of the map covering four other cities. Here is a recent study where he explains how he calculates city wide travel times by simulating walking and public transit
- and finally, Sean Barbeau and Aaron Antrim wrote a nice piece on the many uses of GTFS data (slides)
I must be missing some other initiatives and publications, so please leave a comment to this post with suggestions and links if you remember any.
[image credit: Transit Accessibility for the Minneapolis St. Paul region from the Accessibility Observatory]
