First of twin tunnels complete as Cross River Rail reaches another major milestone
16 Dec 2021
One of Cross River Rail’s twin tunnels is now fully excavated, with the first of the project’s two massive Tunnel Boring Machines recently completing its 294-day journey below the Brisbane River and CBD.
TBM Else’s breakthrough at Cross River Rail’s northern portal is a significant milestone for the project.
Cross River Rail will transform travel to, from and through Brisbane in the future, and the project’s twin tunnels are central to that.
The breakthrough marked the end of tunnelling for TBM Else – named after trailblazing engineer Professor Else Shepherd AM.
Since completing her journey, TBM Else is being disassembled and lifted out of the northern portal piece-by-piece by the same 280-tonne gantry crane that lowered her into the Woolloongabba station box in early 2021.
Cross River Rail’s second mega machine – TBM Merle – is expected to breakthrough into the northern portal any day now, bringing the project’s year of tunnelling to an end.
The northern portal is an impressive site in its own right, with its 40-strong crew working 24/7 to finish excavating the 12-metre-deep TBM extraction box, ensuring it was ready for the arrival of the project’s two mega machines.
All up, 240 pre-cast roof components, each 18 metres wide and weighing almost 26 tonnes are being installed on the site, which is where trains will enter and exit the twin tunnels when Cross River Rail is operational.
TBM Else breakthrough fast facts:
- TBM Else has broken through at Cross River Rail’s northern portal, having excavated 3.8km of tunnel since launching from Woolloongabba in early 2021.
- TBMs excavate the bulk (3.8km) of Cross River Rail’s 5.9km twin tunnels, with the rest excavated by roadheaders.
- TBM Else has excavated 155,000 cubic metres of spoil and installed approximately 13,500 concrete segments to line the tunnel’s walls, each weighing about 4.2 tonnes.
- At its deepest point, TBM Else tunnelled 58 metres below the surface of Kangaroo Point, and 42 metres below the Brisbane River.
- Each TBM weighs 1,350 tonnes and is 165 metres long.
- A crew of up to 15 people work in a TBM at any one time.
- TBMs work at a rate of 20 to 30 metres a day.
- About 37,000 cubic metres of spoil have been excavated at Cross River Rail’s northern portal, which is where trains will enter and exit the twin tunnels.
- The northern portal is 405 metres long and up to 12-metres deep, and will include about 240 pre-cast roof components, each 18 metres wide and weighing 25.7 tonnes.
- After the TBMs breakthrough, they will be disassembled and cleaned inside the extraction box before being lifted out piece by piece, moved to a storage area on site and then loaded onto oversized trucks for removal.
- The TBMs are expected to then be re-used on other tunnelling projects.