BEIJING — The construction of Asia's largest underground transportation complex is proceeding smoothly in Beijing, as the work on the station building core area has started.

Engineers have broken ground on this key part of the large structure that makes up the Beijing subcenter comprehensive transportation hub, located in east Beijing's Tongzhou district, according to China Railway Construction Corporation, one of the project's developers.

The 1.28 million-square-meter traffic complex with a three-layer underground structure is another mega project in the Chinese capital after the Beijing Daxing International Airport.

The project is scheduled to be ready for traffic by the end of 2024, linking cross-regional and intercity railways, and several metro lines.