Whether they transport freight or people, railways these days win the contest hands down over trucks or planes on the carbon footprint issue.
It might not have been the case when locomotives were coal powered as when I took a train ride from Paris to Dijon back in early 60's.
On May 12, celebrate National Train Day 2012, have a green saturday.
"Attendees in New York, Philadelphia, Chicago and Los Angeles will have the chance to tour private luxury railcars, freight and commuter trains, as well as current Amtrak equipment. There will be no ticketing system this year, so be sure to arrive early! Space is limited and on a first-come, first-served basis. Exhibits open at 11:00 a.m. on May 12."