Legacy Way will be built using two tunnel boring machines (TBMs), each 12.4 metres in diameter and approximately 110 metres in length. Construction will involve tunnelling beneath Toowong, Auchenflower, Milton, Paddington, Red Hill and Kelvin Grove. Surface works will also be undertaken at Toowong, to create the tunnel’s connection to the Western Freeway, and Kelvin Grove, where Legacy Way will connect to the Inner City Bypass.
It will take each TBM about 12 months to complete its journey from the western portal at Toowong to the eastern portal at Kelvin Grove, with the first TBM launched in August 2012 and the second TBM launched in October 2012.
The specially imported double-shield TBMs, each weighing approximately 2,800 tonnes, excavate spoil from the tunnel while lining the tunnel with precast concrete segments which form the tunnel wall. For more information, check out our tunnelling fact sheets.
Following the excavation of the twin parallel tunnels, a series of safety, mechanical and electrical systems need to be installed to provide a safe driving environment for motorists.
The first step of the tunnel fit out involves the excavation of cross passages and substations between the two main tunnels. Once these have been excavated, construction of the tunnels’ road surface and installation of its mechanical and electrical systems can be completed.
Construction of Legacy Way started in April 2011 with site establishment at the western worksite, located near the corner of the Western Freeway and Mt Coot-tha Road in Toowong. In June 2011, construction started at the eastern worksite, located adjacent to the Inner City Bypass in Kelvin Grove, in preparation for the extraction of the TBMs in late 2013. To see how the two portals connect, check out the alignment map.
As part of the project, an upgrade to the Moggill Road and Western Freeway interchange is required prior to the opening of the tunnel in 2015.