Dr. Nathan Yau, PhD, who runs the FlowingDate blog, has produced a series of maps for cities both large and small around the country, using the app RunKeeper to source data. The app Strava, for bikers, according to Dr. Yau, would also work in the same way and has been used to good effect before (although on an individual basis).
As Dr. Yau aptly points out: “[the visualization] can be useful to the data collectors to plan future workouts or even city planners who make sure citizens have proper bike lanes and running paths.”
And here’s Dr. Yau’s initial takeaway about what the maps say about how runners make use of the public realm: “If there's one quick (and expected) takeaway, it's that people like to run by the water and in parks, probably to get away from cars and the scenery. In the smaller inland cities, there seem to be a few high-traffic roads with less running elsewhere.”