Maintenance worker Yang Yong cleans and checks the components of a filter at the north maintenance workshop of the Zhengzhou locomotive depot in Zhengzhou, central China's Henan Province, Aug. 6, 2020. As a result of the growing travel demand in summer, the amount of maintenance tasks at the north maintenance workshop of the Zhengzhou locomotive deport is on a rise. More than 100 maintenance workers on Thursday were busy repairing trains at the workshop where it was hot and stuffy. (Xinhua/Li An)

Maintenance worker Jia Nan drinks water during break as his working clothes has been soaked with sweat at the north maintenance workshop of the Zhengzhou locomotive depot in Zhengzhou, central China's Henan Province, Aug. 6, 2020. As a result of the growing travel demand in summer, the amount of maintenance tasks at the north maintenance workshop of the Zhengzhou locomotive deport is on a rise. More than 100 maintenance workers on Thursday were busy repairing trains at the workshop where it was hot and stuffy. (Xinhua/Li An)

Maintenance worker Jia Nan drinks water during break at the north maintenance workshop of the Zhengzhou locomotive depot in Zhengzhou, central China's Henan Province, Aug. 6, 2020. As a result of the growing travel demand in summer, the amount of maintenance tasks at the north maintenance workshop of the Zhengzhou locomotive deport is on a rise. More than 100 maintenance workers on Thursday were busy repairing trains at the workshop where it was hot and stuffy. (Xinhua/Li An)

Maintenance worker Chu Mengting (L) and Zhao Guojun conduct assembling and checking works to the head cover of a train at the north maintenance workshop of the Zhengzhou locomotive depot in Zhengzhou, central China's Henan Province, Aug. 6, 2020. As a result of the growing travel demand in summer, the amount of maintenance tasks at the north maintenance workshop of the Zhengzhou locomotive deport is on a rise. More than 100 maintenance workers on Thursday were busy repairing trains at the workshop where it was hot and stuffy. (Xinhua/Li Jianan)

Maintenance worker Yuan Yuan works at the north maintenance workshop of the Zhengzhou locomotive depot in Zhengzhou, central China's Henan Province, Aug. 6, 2020. As a result of the growing travel demand in summer, the amount of maintenance tasks at the north maintenance workshop of the Zhengzhou locomotive deport is on a rise. More than 100 maintenance workers on Thursday were busy repairing trains at the workshop where it was hot and stuffy. (Xinhua/Li An)

Maintenance workers conduct maintenance works to a train at the north maintenance workshop of the Zhengzhou locomotive depot in Zhengzhou, central China's Henan Province, Aug. 6, 2020. As a result of the growing travel demand in summer, the amount of maintenance tasks at the north maintenance workshop of the Zhengzhou locomotive deport is on a rise. More than 100 maintenance workers on Thursday were busy repairing trains at the workshop where it was hot and stuffy. (Xinhua/Li An)

Maintenance worker Yuan Yuan prepares to work on the head cover of a train at the north maintenance workshop of the Zhengzhou locomotive depot in Zhengzhou, central China's Henan Province, Aug. 6, 2020. As a result of the growing travel demand in summer, the amount of maintenance tasks at the north maintenance workshop of the Zhengzhou locomotive deport is on a rise. More than 100 maintenance workers on Thursday were busy repairing trains at the workshop where it was hot and stuffy. (Xinhua/Li An)

Maintenance worker Chu Mengting conducts assembling works to the head cover of a train at the north maintenance workshop of the Zhengzhou locomotive depot in Zhengzhou, central China's Henan Province, Aug. 6, 2020. As a result of the growing travel demand in summer, the amount of maintenance tasks at the north maintenance workshop of the Zhengzhou locomotive deport is on a rise. More than 100 maintenance workers on Thursday were busy repairing trains at the workshop where it was hot and stuffy. (Xinhua/Li Jianan)

Maintenance worker Jia Nan checks the control power box of a train at the north maintenance workshop of the Zhengzhou locomotive depot in Zhengzhou, central China's Henan Province, Aug. 6, 2020. As a result of the growing travel demand in summer, the amount of maintenance tasks at the north maintenance workshop of the Zhengzhou locomotive deport is on a rise. More than 100 maintenance workers on Thursday were busy repairing trains at the workshop where it was hot and stuffy. (Xinhua/Li An)

Maintenance worker Yuan Yuan adjusts and checks the technical parameters of the pantograph type current collector at the north maintenance workshop of the Zhengzhou locomotive depot in Zhengzhou, central China's Henan Province, Aug. 6, 2020. As a result of the growing travel demand in summer, the amount of maintenance tasks at the north maintenance workshop of the Zhengzhou locomotive deport is on a rise. More than 100 maintenance workers on Thursday were busy repairing trains at the workshop where it was hot and stuffy. (Xinhua/Li Jianan)

Maintenance worker Chu Mengting conducts assembling works to the head cover of a train at the north maintenance workshop of the Zhengzhou locomotive depot in Zhengzhou, central China's Henan Province, Aug. 6, 2020. As a result of the growing travel demand in summer, the amount of maintenance tasks at the north maintenance workshop of the Zhengzhou locomotive deport is on a rise. More than 100 maintenance workers on Thursday were busy repairing trains at the workshop where it was hot and stuffy. (Xinhua/Li An)

Maintenance worker Yuan Yuan prepares to board the head cover of a train at the north maintenance workshop of the Zhengzhou locomotive depot in Zhengzhou, central China's Henan Province, Aug. 6, 2020. As a result of the growing travel demand in summer, the amount of maintenance tasks at the north maintenance workshop of the Zhengzhou locomotive deport is on a rise. More than 100 maintenance workers on Thursday were busy repairing trains at the workshop where it was hot and stuffy. (Xinhua/Li Jianan)

Maintenance workers conduct maintenance works to a train at the north maintenance workshop of the Zhengzhou locomotive depot in Zhengzhou, central China's Henan Province, Aug. 6, 2020. As a result of the growing travel demand in summer, the amount of maintenance tasks at the north maintenance workshop of the Zhengzhou locomotive deport is on a rise. More than 100 maintenance workers on Thursday were busy repairing trains at the workshop where it was hot and stuffy. (Xinhua/Li Jianan)

A maintenance worker cleans the windshield of a train at the north maintenance workshop of the Zhengzhou locomotive depot in Zhengzhou, central China's Henan Province, Aug. 6, 2020. As a result of the growing travel demand in summer, the amount of maintenance tasks at the north maintenance workshop of the Zhengzhou locomotive deport is on a rise. More than 100 maintenance workers on Thursday were busy repairing trains at the workshop where it was hot and stuffy. (Xinhua/Li Jianan)