Boston the walking city

Spotted this data visualization by the creators of the "Human app" for the iPhone. I don't have an iPhone so I'll let them explain it:

Human is an iPhone app that runs in the background of your phone and automatically detects activities like walking, cycling, running, and motorized transport. All visualizations are solely based on aggregated data from people using the Human app. Imagery shown does not involve the use of maps, as white pixels were drawn by moving Humans.

Walking in Boston as measured by the app (source)

In addition, it finds that 46% of activity in Boston was walking, compared to 43% motorized, 4% running, and 6% bicycling. I also noticed that the visualization of motorized activity includes the surface portions of all the MBTA rail lines: if you look closely you can see them all traced out pretty clearly where they diverge from other roadways. No tunnels are included in the charts at all, presumably because GPS doesn't work underground. So, it seems that in this case, "motorized activity" also includes riding the T. Boston's high walking rate puts it in the top ten worldwide, and only behind Washington, D.C. and New York City in the United States.

I think that's a nice confirmation of what we already knew from census and survey data. If anything, it may show that those estimates were too low, especially since they often focus only on journey to work, which is usually considered to comprise about 20% of total trips. I think that the main criticism of this work, and the one thing that holds it back from being scientifically useful, is that it is only measuring people with iPhones AND the Human app. And I have no idea how well iPhones are distributed among the population, but I can guess: they probably skew towards the rich and technologically literate. So there are some fairly egregious gaps in data. For example, much of southern Boston is simply ... missing. I couldn't tell you whether that's because walking is rare there, or because iPhones are less common. Based on personal experience, I don't think walking is rare in neighborhoods like Roxbury and Dorchester, so I think it's more likely that there are just fewer people carrying iPhones with the Human app installed.