A model poses with a road-roller during the 11th China International Exhibition on Transport Technology & Equipment (CHINA TRANSPO 2012), Beijing, May 15, 2012. CHINA TRANSPO 2012 kicks off at the Beijing Exhibition Center Tuesday. More than 400 enterprises from the transportation industry will take part in the four-day long expo. [Photo/Xinhua]

A road in downtown Changsha, Hunan province, caves in on May 15, 2012. As reconstruction work began, the cause of the cave-in was not known. [Photo/CFP]