A worker inspects the overhead line system at a section of the Nanning-Guangzhou railway in south China's Guangxi Zhuang Autonomous Region, Jan. 26, 2021. Workers here have been checking and maintaining the overhead line system along Nanning-Guangzhou railway to ensure traffic safety during the upcoming Spring Festival travel rush. (Xinhua/Zhang Ailin)

A worker inspects the overhead line system at a section of the Nanning-Guangzhou railway in south China's Guangxi Zhuang Autonomous Region, Jan. 25, 2021. Workers here have been checking and maintaining the overhead line system along Nanning-Guangzhou railway to ensure traffic safety during the upcoming Spring Festival travel rush. (Xinhua/Zhang Ailin)

Workers inspect the overhead line system at a section of the Nanning-Guangzhou railway in south China's Guangxi Zhuang Autonomous Region, Jan. 25, 2021. Workers here have been checking and maintaining the overhead line system along Nanning-Guangzhou railway to ensure traffic safety during the upcoming Spring Festival travel rush. (Xinhua/Zhang Ailin)

Workers prepare to inspect the overhead line system at a section of the Nanning-Guangzhou railway in south China's Guangxi Zhuang Autonomous Region, Jan. 25, 2021. Workers here have been checking and maintaining the overhead line system along Nanning-Guangzhou railway to ensure traffic safety during the upcoming Spring Festival travel rush. (Xinhua/Zhang Ailin)

Workers inspect the overhead line system at a section of the Nanning-Guangzhou railway in south China's Guangxi Zhuang Autonomous Region, Jan. 25, 2021. Workers here have been checking and maintaining the overhead line system along Nanning-Guangzhou railway to ensure traffic safety during the upcoming Spring Festival travel rush. (Xinhua/Zhang Ailin)

Workers inspect the overhead line system at a section of the Nanning-Guangzhou railway in south China's Guangxi Zhuang Autonomous Region, Jan. 25, 2021. Workers here have been checking and maintaining the overhead line system along Nanning-Guangzhou railway to ensure traffic safety during the upcoming Spring Festival travel rush. (Xinhua/Zhang Ailin)

A worker inspects the overhead line system at a section of the Nanning-Guangzhou railway in south China's Guangxi Zhuang Autonomous Region, Jan. 25, 2021. Workers here have been checking and maintaining the overhead line system along Nanning-Guangzhou railway to ensure traffic safety during the upcoming Spring Festival travel rush. (Xinhua/Zhang Ailin)

Workers inspect the overhead line system at a section of the Nanning-Guangzhou railway in south China's Guangxi Zhuang Autonomous Region, Jan. 25, 2021. Workers here have been checking and maintaining the overhead line system along Nanning-Guangzhou railway to ensure traffic safety during the upcoming Spring Festival travel rush. (Xinhua/Zhang Ailin)

Workers inspect the overhead line system at a section of the Nanning-Guangzhou railway in south China's Guangxi Zhuang Autonomous Region, Jan. 26, 2021. Workers here have been checking and maintaining the overhead line system along Nanning-Guangzhou railway to ensure traffic safety during the upcoming Spring Festival travel rush. (Xinhua/Zhang Ailin)

Workers inspect the overhead line system at a section of the Nanning-Guangzhou railway in south China's Guangxi Zhuang Autonomous Region, Jan. 25, 2021. Workers here have been checking and maintaining the overhead line system along Nanning-Guangzhou railway to ensure traffic safety during the upcoming Spring Festival travel rush. (Xinhua/Zhang Ailin)

A worker inspects the overhead line system at a section of the Nanning-Guangzhou railway in south China's Guangxi Zhuang Autonomous Region, Jan. 25, 2021. Workers here have been checking and maintaining the overhead line system along Nanning-Guangzhou railway to ensure traffic safety during the upcoming Spring Festival travel rush. (Xinhua/Zhang Ailin)

Workers inspect the overhead line system at a section of the Nanning-Guangzhou railway in south China's Guangxi Zhuang Autonomous Region, Jan. 26, 2021. Workers here have been checking and maintaining the overhead line system along Nanning-Guangzhou railway to ensure traffic safety during the upcoming Spring Festival travel rush. (Xinhua/Zhang Ailin)

Workers inspect the overhead line system at a section of the Nanning-Guangzhou railway in south China's Guangxi Zhuang Autonomous Region, Jan. 26, 2021. Workers here have been checking and maintaining the overhead line system along Nanning-Guangzhou railway to ensure traffic safety during the upcoming Spring Festival travel rush. (Xinhua/Zhang Ailin)

Workers inspect the overhead line system at a section of the Nanning-Guangzhou railway in south China's Guangxi Zhuang Autonomous Region, Jan. 25, 2021. Workers here have been checking and maintaining the overhead line system along Nanning-Guangzhou railway to ensure traffic safety during the upcoming Spring Festival travel rush. (Xinhua/Zhang Ailin)

Workers inspect the overhead line system at a section of the Nanning-Guangzhou railway in south China's Guangxi Zhuang Autonomous Region, Jan. 25, 2021. Workers here have been checking and maintaining the overhead line system along Nanning-Guangzhou railway to ensure traffic safety during the upcoming Spring Festival travel rush. (Xinhua/Zhang Ailin)

Workers inspect the overhead line system at a section of the Nanning-Guangzhou railway in south China's Guangxi Zhuang Autonomous Region, Jan. 26, 2021. Workers here have been checking and maintaining the overhead line system along Nanning-Guangzhou railway to ensure traffic safety during the upcoming Spring Festival travel rush. (Xinhua/Zhang Ailin)

A worker inspects the overhead line system at a section of the Nanning-Guangzhou railway in south China's Guangxi Zhuang Autonomous Region, Jan. 26, 2021. Workers here have been checking and maintaining the overhead line system along Nanning-Guangzhou railway to ensure traffic safety during the upcoming Spring Festival travel rush. (Xinhua/Zhang Ailin)