Approximately 9000 rings of concrete, each made up of six segments, are required to build the tunnels for the Forrestfield-Airport Link. A purpose-built segment production facility was commissioned at Forrestfield in April 2017. Two years on, in April 2019, the production of all segments - totalling more than 54,000 - was completed.
Testing the concrete
As part of preparations for the manufacture of the pre-cast segments, the concrete underwent a series of tests to ensure it met the required standards for strength and durability.
Prior to installing the first segment rings, fire testing on the concrete for this project was completed in Victoria, Australia and Germany.
The pre-cast segments were constructed using steel moulds and a concrete mix specifically designed to meet the specifications of this project. A carousel system was used to move the moulds through various workstations. After fitting materials such as gaskets and installing steel reinforcement, the concrete was poured and trowelled before being left to steam cure for several hours. Segments then underwent a series of assessments before being painted and stored for transport to the Forrestfield, Airport Central Station and Redcliffe sites.
A purpose-built multi-service vehicle (MSV) is used to cart the segments to the tunnel boring machines.
Watch a video on how the tunnel segments were constructed.