A train makes a test run on the line linking Beijing Daxing International Airport to the city's downtown area on Aug. 29, 2019. It will take only 19 minutes to get from the Caoqiao Subway Station to Beijing Daxing International Airport after it starts operation on Sept. 30. (Photo: China News Service/Fu Tian)
Sand bags are placed inside a train during a test run of the new subway line connecting downtown Beijing and Beijing Daxing International Airport, Aug. 29, 2019. (Photo: China News Service/Fu Tian)
An inside view of a train for the new subway line connecting downtown Beijing and Beijing Daxing International Airport, Aug. 29, 2019. (Photo: China News Service/Fu Tian)
An inside view of a train for the new subway line connecting downtown Beijing and Beijing Daxing International Airport, Aug. 29, 2019. (Photo: China News Service/Fu Tian)
An inside view of a train for the new subway line connecting downtown Beijing and Beijing Daxing International Airport, Aug. 29, 2019. (Photo: China News Service/Fu Tian)
Photo taken on Aug. 29, 2019 shows the Caoqiao Subway Station featuring an arched structure at the entrance. (Photo: China News Service/Fu Tian)
An inside view of the Caoqiao Subway Station in Beijing, Aug. 29, 2019. It will take only 19 minutes to get from the station to Beijing Daxing International Airport after it starts operation on Sept. 30. (Photo: China News Service/Fu Tian)
An inside view of the Caoqiao Subway Station in Beijing, Aug. 29, 2019. It will take only 19 minutes to get from the station to Beijing Daxing International Airport after it starts operation on Sept. 30. (Photo: China News Service/Fu Tian)
An inside view of the Caoqiao Subway Station in Beijing, Aug. 29, 2019. It will take only 19 minutes to get from the station to Beijing Daxing International Airport after it starts operation on Sept. 30. (Photo: China News Service/Fu Tian)
An inside view of the Caoqiao Subway Station in Beijing, Aug. 29, 2019. It will take only 19 minutes to get from the station to Beijing Daxing International Airport after it starts operation on Sept. 30. (Photo: China News Service/Fu Tian)
The subway station at Beijing Daxing International Airport, Aug. 29, 2019. (Photo: China News Service/Fu Tian)
The subway station at Beijing Daxing International Airport, Aug. 29, 2019. (Photo: China News Service/Fu Tian)
The subway station at Beijing Daxing International Airport, Aug. 29, 2019. (Photo: China News Service/Fu Tian)
The Xincheng Subway Station of the new line connecting downtown Beijing and Beijing Daxing International Airport, Aug. 29, 2019. (Photo: China News Service/Fu Tian)