People wait on a platform at the Dongsi Station of the newly-opened subway line 6 in Beijing, capital of China, on Dec 30, 2012. Beijing put four subway lines into operation on Sunday, part of the city's efforts to expand rail transit to ease severe traffic congestion. The new lines bring the number of subway lines in Beijing to 16, with a total length of 442 kilometers, according to authorities. [Photo/Xinhua]