500m is a little over a quarter of a mile and can be walked by an average person in just over 6 minutes, if the author extended those radii by 250m to 750, it w

500m is a little over a quarter of a mile and can be walked by an average person in just over 6 minutes, if the author extended those radii by 250m to 750, it would be closer to half a mile, which a person can walk in about 10 minutes and, probably represents a more realistic view of how long someone will walk to the subway. That said, I used to live a little over a half mile from the Nassau Av G station. There was a bus that would take me there, but I eventually figured out that unless I saw the bus was a block or two away from my corner, it would just be quicker to walk to the station, rather than wait for the bus.