It means the 5.9 km of twin tunnels, under the Brisbane River and the CBD, have now been drilled by two massive tunnel boring machines, known as TBMs.

Premier Annastacia Palaszczuk announced the milestone, saying “the Brisbane underground is through”.

During the drilling process, 310,000 cubic metres of rock was removed, the equivalent of 124 swimming pools, as the two machines drilled their way underground across the river in 282 days.

The rock removed will be used to make bricks for the housing industry.

The Cross River Rail project involves a 10.2 km rail line from Dutton Park to Bowen Hills and aims to unlock a bottleneck and ease transport across the State’s south east.

“It is wonderful to see this major milestone of Cross River Rail has happened. To all the hundreds of workers on this project, this is a great day. This is a fantastic Christmas present to all the people who have been involved,” Palaszczuk said at the site.

The new rail line will also assist with transport during the 2032 Olympic Games in Brisbane.

The drilling machine, known as Else, finished drilling the first tunnel, from Woolloongabba to the Exhibtion grounds, in late November.

The second machine, Merle, completed its job on Friday.

The Cross River Rail project is estimated to cost $5.4 billion by completion and involves Brisbane CBD getting its first new train station in more than a century.