Passengers are seen at the Railway Station in Xining City, capital of northwest China's Qinghai Province, Feb. 23, 2015. China saw a passenger flow return peak on Monday as the week-long Lunar New Year holiday drew to an end. (Xinhua/Zhang Hongxiang)

Passengers prepare to get on trains at the Railway Station in Xining City, capital of northwest China's Qinghai Province, Feb. 23, 2015. China saw a passenger flow return peak on Monday as the week-long Lunar New Year holiday drew to an end. (Xinhua/Zhang Hongxiang)

Passengers queue to board trains at the Railway Station in Xining City, capital of northwest China's Qinghai Province, Feb. 23, 2015. China saw a passenger flow return peak on Monday as the week-long Lunar New Year holiday drew to an end. (Xinhua/Zhang Hongxiang)

Passengers queue to board trains at the Railway Station in Xining City, capital of northwest China's Qinghai Province, Feb. 23, 2015. China saw a passenger flow return peak on Monday as the week-long Lunar New Year holiday drew to an end. (Xinhua/Zhang Hongxiang)

Passengers prepare to get on trains at the Railway Station in Xining City, capital of northwest China's Qinghai Province, Feb. 23, 2015. China saw a passenger flow return peak on Monday as the week-long Lunar New Year holiday drew to an end. (Xinhua/Zhang Hongxiang) 

Passengers wait to board trains at the Railway Station in Wuhan, capital city of central China's Hubei Province, Feb. 23, 2015. China saw a passenger flow return peak on Monday as the week-long Lunar New Year holiday drew to an end. (Xinhua/Cheng Min)

A policeman stands guard as passengers prepare to board trains at the Railway Station in Wuhan, capital city of central China's Hubei Province, Feb. 23, 2015. China saw a passenger flow return peak on Monday as the week-long Lunar New Year holiday drew to an end. (Xinhua/Cheng Min)

Passengers prepare to board trains at the Railway Station in Wuhan, capital city of central China's Hubei Province, Feb. 23, 2015. China saw a passenger flow return peak on Monday as the week-long Lunar New Year holiday drew to an end. (Xinhua/Cheng Min)