John Carmody (Center for Sustainable Building Research) is cited in "SubTropolis, USA" by Steve Nadis for the Atlantic. The article takes a look at SubTropolis, an enterprise zone where more than 50 Kansas City businesses have a presence underneath city amusement parks. "With five million square feet of leased warehouse, light-industry, and office space, and a network of more than two miles of rail lines and six miles of roads, SubTropolis is the world's largest underground business complex--and one of eight or so in the area," writes Nadis.
Nadis cites Carmody as saying that "because no trees or other plants need to be cut, nor wetlands filled, to make way for commerce or industry, a business's environmental impact can be smaller." Carmody tells Nadis, "by putting more resources underground, you can preserve surface land and make a denser city."
Update: May 3, 2010: Updated to reflect Nadis article was originally published in the Atlantic. The Nadis article was republished by Urban Transport.