The 22m long and 115t machines excavated almost 900m of tunnel each, since launching from Woolloongabba at the start of the year as the new 10.2km rail line from Dutton Park to Bowen Hills is constructed.

The roadheaders finished carving Cross River Rail's tunnels towards Boggo Road in September, having advanced about 30m a week through hard rock.

It marked a particularly impressive feat of engineering, with the roadheaders working as shallow as 8m below ground at some points, including beneath live rail lines.

While the project's massive tunnel boring machines usually receive the most attention, the roadheaders are impressive pieces of machinery in their own right. The machines and the crews who operate them are said to be the unsung workhorses of the project, responsible for not only mining the tunnels from Woolloongabba to Boggo Road, but excavating the project's station caverns as well.

Meanwhile, work on the future Boggo Road station itself has been progressing well. The 27m deep station box is now fully excavated and the walls for the station structure itself are being installed.

The site also boasts two of the world's strongest tower cranes, each capable of lifting 330t each - the equivalent of about 47 African elephants.