Aerial photo taken on Oct. 1, 2018 shows Beijing Daxing International Airport under construction in Beijing, capital of China. June 30 marks the end of the new airport infrastructure construction and the start of the preparatory stage of the airport's operation. The new airport is scheduled to be put into operation before Sept. 30. (Xinhua/Ju Huanzong)

BEIJING, June 30 (Xinhua) -- Construction of the Beijing Daxing International Airport was completed as scheduled on Sunday, and preparations have started for the operation of what is expected to be one of the world's busiest air traffic hubs.

In the first half of this year, projects including the airport's main construction, air traffic control and aviation oil facilities, and interlinked expressways and high-speed railway have been completed on schedule and given the green light to be put into operation.

"It is the world's largest integrated transportation hub. The terminal building is also the world's largest built with a seamless steel structure, boasting the world's first design of double-deck departure and double-deck arrival platforms," said Bai Henghong, director of the Beijing Daxing International Airport project command of Beijing Construction Group.

Six major test runs are arranged to further assess the airport's operation readiness and fix possible problems. There will be a total of 787 tests involving 500 flights and some 52,000 simulated passenger trips.

The airport, scheduled to be operational before Sept. 30, will become a pivotal air traffic hub for international travel to and from China, supporting China's growth to become the world's largest civil aviation market, which is forecast to be around the mid-2020s.

Located 46 km south of downtown Beijing, it was designed to take the pressure off the overcrowded Beijing Capital International Airport in the northeastern suburb.

It is forecast to see its passenger throughput reach 72 million in 2025, and further increase to 100 million by 2040, when it is likely to surpass Hartsfield-Jackson Atlanta International Airport in the United States to become the world's largest airport in passenger throughput.