A welder works on a train in a maintenance garage in Nanning, south China's Guangxi Zhuang Autonomous Region, Aug. 14, 2020. To ensure the safe operation of train during the summer holiday, Nanning railway had the slow-speed trains overhauled recently. (Xinhua/Cao Yiming)

Welders work in a maintenance garage in Nanning, south China's Guangxi Zhuang Autonomous Region, Aug. 14, 2020. To ensure the safe operation of train during the summer holiday, Nanning railway had the slow-speed trains overhauled recently. (Xinhua/Zhou Hua)

A welder works on a train in a maintenance garage in Nanning, south China's Guangxi Zhuang Autonomous Region, Aug. 14, 2020. To ensure the safe operation of train during the summer holiday, Nanning railway had the slow-speed trains overhauled recently. (Xinhua/Zhou Hua)

A welder works on a train in a maintenance garage in Nanning, south China's Guangxi Zhuang Autonomous Region, Aug. 14, 2020. To ensure the safe operation of train during the summer holiday, Nanning railway had the slow-speed trains overhauled recently. (Xinhua/Cao Yiming)

A welder works on a train in a maintenance garage in Nanning, south China's Guangxi Zhuang Autonomous Region, Aug. 14, 2020. To ensure the safe operation of train during the summer holiday, Nanning railway had the slow-speed trains overhauled recently. (Xinhua/Cao Yiming)

Welders pose for photos in a maintenance garage in Nanning, south China's Guangxi Zhuang Autonomous Region, Aug. 14, 2020. To ensure the safe operation of train during the summer holiday, Nanning railway had the slow-speed trains overhauled recently. (Xinhua/Cao Yiming)

A welder works on a train in a maintenance garage in Nanning, south China's Guangxi Zhuang Autonomous Region, Aug. 14, 2020. To ensure the safe operation of train during the summer holiday, Nanning railway had the slow-speed trains overhauled recently. (Xinhua/Cao Yiming)

A welder works on a train in a maintenance garage in Nanning, south China's Guangxi Zhuang Autonomous Region, Aug. 14, 2020. To ensure the safe operation of train during the summer holiday, Nanning railway had the slow-speed trains overhauled recently. (Xinhua/Cao Yiming)