New York? Shanghai? Beijing? All of the above? Sizing up the world's biggest metro is no easy challenge. Thanks to a surprising number of variables there is no single standard for comparing subway systems. With that in mind, a three-part series by the folks at CityMetric
makes an impressive effort to sort out the issue. Overall system length
, total number of stations
, and annual ridership
are each examined. Category killers are summed up in a trio of top ten lists.