I'd like to see (light grey) concentric circles for 10min, 20min, 30min 40min, 50min, that way can more accurately determine the distance.
Right now r = 30 min, so just use the circle without the label and scale it down, then add it at the same lines the hour circle is touched: https://github.com/nate-parrott/subway/search?utf8=%E2%9C%93...