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. 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. [Xinhua]