A little passenger waves his hand at a low-speed green train from southwest China's Chongqing Municipality to Neijiang City of southwest China's Sichuan Province, Jan. 31, 2019. Low-speed green trains are still in operation as bullet trains run past new stations throughout China. The old-fashioned green trains are a low-cost alternative for people to travel during the 2019 Spring Festival travel rush. (Xinhua/Liu Chan)

A railway staff member (R) provides hot water for a passenger at a low-speed green train from southwest China's Chongqing Municipality to Neijiang City of southwest China's Sichuan Province, Jan. 31, 2019. Low-speed green trains are still in operation as bullet trains run past new stations throughout China. The old-fashioned green trains are a low-cost alternative for people to travel during the 2019 Spring Festival travel rush. (Xinhua/Liu Chan)

Two elderly passengers chat at a low-speed green train from southwest China's Chongqing Municipality to Neijiang City of southwest China's Sichuan Province, Jan. 31, 2019. Low-speed green trains are still in operation as bullet trains run past new stations throughout China. The old-fashioned green trains are a low-cost alternative for people to travel during the 2019 Spring Festival travel rush. (Xinhua/Liu Chan)

A passenger displays Spring Festival gifts at a low-speed green train from southwest China's Chongqing Municipality to Neijiang City of southwest China's Sichuan Province, Jan. 31, 2019. Low-speed green trains are still in operation as bullet trains run past new stations throughout China. The old-fashioned green trains are a low-cost alternative for people to travel during the 2019 Spring Festival travel rush. (Xinhua/Liu Chan)

A passenger reads a book at a low-speed green train from southwest China's Chongqing Municipality to Neijiang City of southwest China's Sichuan Province, Jan. 31, 2019. Low-speed green trains are still in operation as bullet trains run past new stations throughout China. The old-fashioned green trains are a low-cost alternative for people to travel during the 2019 Spring Festival travel rush. (Xinhua/Liu Chan)

A train conductor (2nd L) explains travel safety rules to two kids at a low-speed green train from southwest China's Chongqing Municipality to Neijiang City of southwest China's Sichuan Province, Jan. 31, 2019. Low-speed green trains are still in operation as bullet trains run past new stations throughout China. The old-fashioned green trains are a low-cost alternative for people to travel during the 2019 Spring Festival travel rush. (Xinhua/Liu Chan)

Passengers board a low-speed green train at the Chongqing Railway Station in Chongqing, southwest China, Jan. 31, 2019. Low-speed green trains are still in operation as bullet trains run past new stations throughout China. The old-fashioned green trains are a low-cost alternative for people to travel during the 2019 Spring Festival travel rush. (Xinhua/Liu Chan)

A railway staff member (1st L) hands a vacuum flask of hot water to a passenger at a low-speed green train from southwest China's Chongqing Municipality to Neijiang City of southwest China's Sichuan Province, Jan. 31, 2019. Low-speed green trains are still in operation as bullet trains run past new stations throughout China. The old-fashioned green trains are a low-cost alternative for people to travel during the 2019 Spring Festival travel rush. (Xinhua/Liu Chan)

A railway policeman checks a fire extinguisher at a low-speed green train from southwest China's Chongqing Municipality to Neijiang City of southwest China's Sichuan Province, Jan. 31, 2019. Low-speed green trains are still in operation as bullet trains run past new stations throughout China. The old-fashioned green trains are a low-cost alternative for people to travel during the 2019 Spring Festival travel rush. (Xinhua/Liu Chan)

A train broadcaster plays music for passengers at a low-speed green train from southwest China's Chongqing Municipality to Neijiang City of southwest China's Sichuan Province, Jan. 31, 2019. Low-speed green trains are still in operation as bullet trains run past new stations throughout China. The old-fashioned green trains are a low-cost alternative for people to travel during the 2019 Spring Festival travel rush. (Xinhua/Liu Chan)

A passenger talks with her family members via a video call at a low-speed green train from southwest China's Chongqing Municipality to Neijiang City of southwest China's Sichuan Province, Jan. 31, 2019. Low-speed green trains are still in operation as bullet trains run past new stations throughout China. The old-fashioned green trains are a low-cost alternative for people to travel during the 2019 Spring Festival travel rush. (Xinhua/Liu Chan)

A railway policeman warns passengers of travel safety rules at a low-speed green train from southwest China's Chongqing Municipality to Neijiang City of southwest China's Sichuan Province, Jan. 31, 2019. Low-speed green trains are still in operation as bullet trains run past new stations throughout China. The old-fashioned green trains are a low-cost alternative for people to travel during the 2019 Spring Festival travel rush. (Xinhua/Liu Chan)

Passengers get off a low-speed green train at the Jiangjin Railway Station in Jiangjin, southwest China's Chongqing Municipality, Jan. 31, 2019. Low-speed green trains are still in operation as bullet trains run past new stations throughout China. The old-fashioned green trains are a low-cost alternative for people to travel during the 2019 Spring Festival travel rush. (Xinhua/Liu Chan)

A mother and her child read a picture storybook at a low-speed green train from southwest China's Chongqing Municipality to Neijiang City of southwest China's Sichuan Province, Jan. 31, 2019. Low-speed green trains are still in operation as bullet trains run past new stations throughout China. The old-fashioned green trains are a low-cost alternative for people to travel during the 2019 Spring Festival travel rush. (Xinhua/Liu Chan)

A boy does homework at a low-speed green train from southwest China's Chongqing Municipality to Neijiang City of southwest China's Sichuan Province, Jan. 31, 2019. Low-speed green trains are still in operation as bullet trains run past new stations throughout China. The old-fashioned green trains are a low-cost alternative for people to travel during the 2019 Spring Festival travel rush. (Xinhua/Liu Chantonglian)