North Korean women sit in a metro train in Pyongyang August 27, 2007. REUTERS/Reinhard Krause


A tunnel is pictured through the window of a carriage of the new M2 underground line during tests in Lausanne July 30, 2008. REUTERS/Denis Balibouse


A rider emerges from the Union Square subway station in New York, December 15, 2005. REUTERS/Jeff Zelevansky


Thousands of commuters pack the Se train station during rush hour in downtown Sao Paulo April 12, 2006. REUTERS/Paulo Whitaker


A commuter passes a map of the London Underground system at Westminster tube station in London, June 29, 2004. REUTERS/Toby Melville


Passengers crowd into a train inside a station of the Subway Line Number 1 in Beijing July 22, 2008. REUTERS/Jason Lee


A train operator drives out of a station during a media visit to the new Shanghai Metro Line Six, August 9, 2007. REUTERS/Aly Song


Metro Dubai train runs on its first working day in Dubai September 10, 2009. REUTERS/Ahmed Jadallah


People take the first metro ride after the official opening of the Gulf Emirate's first metro network in Dubai September 9, 2009. RUTERS/Mosab Omar


Commuters board a subway train at Taipei's main train station March 17, 2004. REUTERS/Thomas White


couple embraces while waiting for the subway in New York June 5, 2009. REUTERS/Lucas Jackson


Participants wait for the train in the annual No Pants Subway Ride in New York January 13, 2007. The event is run by the group Improv Everywhere, and is intended to make people laugh and have an interesting New York experience. When asked, participants are not supposed to reveal the purpose, they are asked to respond with something such as, I forgot my pants today. REUTERS/Eric Thayer


A man wears a protective mask while taking Mexico City's subway May 6, 2009. REUTERS/Jorge Dan


Train conductor Audrey Shihab opens doors on the subway after service resumed in New York early December 23, 2005. REUTERS/Keith Bedford


Musician Gao Bao Tie plays a traditional Chinese instrument called the Yang-Qin for passers-by in the subway system of New York April 13, 2007. REUTERS/Lucas Jackson


A woman sits on a chair next to a man with a leg brace and crutch while riding the subway in New York April 20, 2009. REUTERS/Lucas Jackson


Revelers dressed as Santa Claus crowd surf while riding the subway as they participate in a Santa themed pub crawl named SantaCon in New York December 8, 2007. REUTERS/Lucas Jackson


Figures are silhouetted in the dark entrance to a Moscow metro station, May 25, 2005. REUTERS/Sergei Karpukhin


A man waits for the train at DeKalb Avenue as he makes his way to National Puerto Rican Day Parade in New York June 8, 2008. REUTERS/Joshua Lott


A person dressed as a Star Wars character travels on the Santiago subway May 7, 2009, during Star Wars: The Exhibition. REUTERS/Victor Ruiz Caballero