The cranes stand tall and machines roar while giant steel skeletons grow by the Northern Grand Canal in eastern Beijing's Tongzhou district. This is the construction site of a huge transportation hub in the subcenter of China's capital.

The Beijing subcenter station has been considered the capital's first large-scale transportation infrastructure project since the Beijing Daxing International Airport. It is expected to be the largest underground hub in Asia.

According to the plan, the comprehensive hub is about 1.28 million square meters; has eight platforms; 14 routes; and is integrated with two intercity railways, one suburban railway, four rail transit lines, 1 canal terminal and 15 bus lines.

The hub project is 2.1 kilometers long from east to west, and 650 meters wide from north to south, with a maximum depth of 47 meters for the foundation pit.

After 4 years of construction, the hub is gradually taking shape, since the concrete work of the platform floor, the bottom of the three-story building, has finally come to an end on Feb 2. The other two floors are an entrance and a waiting hall.

Over 60,000 tons of "steel bones" have been implanted underground in the core area of the entire station building so far, the same weight as over 10,000 Asian elephants combined.

The construction of the entrance floor started in October last year and is expected to be completed within three months, and then the equipment installation and decoration work will start, according to Meng Xiao, the person in charge of the construction work from China Railway Construction Group Co Ltd.

The Spring Festival is approaching quickly. However, to ensure the smooth completion of the platform floor, there are still 216 workers carrying out construction on the site. Xue Jianping from Southwest China's Sichuan province, head of the welder team is one of them.

"After finishing the construction of the platform floor, I can go home in peace for the Spring Festival!" he said, crouching down to carefully check the quality of each wielding spot. He will return to his post on the tenth day of the Year of the Dragon, preparing for the capping of the main structure in May.

Feng Yuehai, the chief safety officer of the hub project, gave up the chance to go home for the Spring Festival to stay at the construction site this year again.

"For an underground 'super project' like the hub, safety arrangements should not be relaxed at all - even in the holiday," Feng said.

The construction and decoration work of the hub is expected to be completed by the end of this year, and it will be put into use next year.