Industrial parks are popular for criterium races ("crits") and practice races, which is probably what you're seeing there. Here's one I've raced in a few times

Industrial parks are popular for criterium races ("crits") and practice races, which is probably what you're seeing there. Here's one I've raced in a few times. Looks like it's not quite as popular, though! http://labs.strava.com/heatmap/#16/-89.48204/43.05660/yellow/bike http://labs.strava.com/heatmap/#16/-89.48204/43.05660/yellow...