A man cradles his baby in his arms as commuters shove each other in a crowded train on a subway line in Beijing July 14, 2010. The capital's subway lines are expected to accommodate a daily volume of 4.8 million people during the summer travel peak of July 15 to August 31. With the advent of the summer vacation, Beijing has seen a rapid increase in the underground commuter population. [Xinhua]

A man takes a nap in an over-crowded train on subway Line 1 in Beijing, July 14, 2010. [Xinhua]