Polygon Isochrone results (using polygons = TRUE) from Mapzen as of
January 10, 2017. The location for the isochrones is the Berkeley Marina,
lat 37.86613, lon -122.3151, and the contours are 10 and 15 minutes for a
pedestrian costing model.
marina_walks_polygonsAn object of class mapzen_isochrone_list (inherits from geo_list) of length 3.