A test train runs on Zhengzhou-Xuzhou high-speed railway, Sept 6, 2016. China's high-speed railways now exceed 20,000 km in length with the opening of a line linking Zhengzhou in Central China's Henan province with Xuzhou in eastern Jiangsu province on Sept 10, 2016. The line connects the west with two major north-south lines, helping cut travel time between west and east in the country. [Photo/Xinhua]

Photo taken on Sept 6, 2016 shows high-speed trains to be overhauled at a maintenance center in Zhengzhou, capital of Central China's Henan Province. [Photo/Xinhua]

A bullet train runs in Zhengzhou, capital of Central China's Henan Province, Sept 1, 2016. [Photo/Xinhua]

Photo taken on Sept 6, 2016 shows high-speed trains to be overhauled at a maintenance center in Zhengzhou, capital of Central China's Henan Province. [Photo/Xinhua]

Photo taken on Sept 6, 2016 shows high-speed trains to be overhauled at a maintenance center in Zhengzhou, capital of Central China's Henan Province. [Photo/Xinhua]

A senior couple show their tickets on the first train operating on Zhengzhou-Xuzhou high-speed railway, Sept 10, 2016. [Photo/Xinhua]

A stewardess serves snacks and beverage on the first train operating on Zhengzhou-Xuzhou high-speed railway, Sept 10, 2016. [Photo/Xinhua]

The first train operating on Zhengzhou-Xuzhou high-speed railway stops at Shangqiu Railway Station, Central China's Henan Province, Sept 10, 2016. [Photo/Xinhua]

A train operating on Zhengzhou-Xuzhou high-speed railway leaves Zhengzhou East Railway Station, Central China's Henan Province, Sept 10, 2016. [Photo/Xinhua]

Stewardess Xia Mengya sends brochures to a passenger on G1802 train from Shanghai to Zhengzhou, Central China's Henan Province, Sept 10, 2016. [Photo/Xinhua]