The route for the Forrestfield-Airport Link includes 8km of twin-bored tunnels, with safe entry and exit points via underground stations at Redcliffe and Airport Central, as well as tunnel portals at Bayswater and Forrestfield.
Given the length of the tunnels, additional infrastructure is required between the stations to allow safe egress to the ground level in the event of an emergency, and access to the tunnels for maintenance.
As such, three emergency egress shafts (EES), twelve tunnel-to-tunnel cross passages and three tunnel-to-egress shaft cross passages will be constructed along the alignment.
View the cross passage and emergency egress shaft construction fact sheet.
View a map of all cross passage and emergency egress shaft locations.
Emergency Egress Shafts
What is an emergency egress shaft?
An EES provides access from the tunnels to ground level via stairs and lifts.
Its layout is designed in conjunction with the Department of Fire and Emergency Services to ensure functionality during an emergency situation.
It takes up to six months to build each EES and another six months to build the supporting ground level infrastructure (ancillary buildings, car park and emergency muster point).
The ancillary buildings house communications, electrical and mechanical equipment and controls. They also contain air vents which will help ventilate the shafts and tunnels.
All three emergency egress shafts are fully excavated and the respective base slabs have been poured.
Works are most advanced at Abernethy Road EES, where the roof of the upper ancillary building – the building erected on top of the shaft – has recently been installed. Fit-out of the shaft is well underway, with two-hour fire-resistant wall lining currently being installed around the mechanical and electrical services for the lift.
Wright Crescent EES holds second place with the building structure adjacent to the shaft in place. The upper building will be erected following construction of the cross passages between shaft and tunnels. The diaphragm walls of the shaft were recently cut with a 1.2m-diametre saw, marking the start of the cross passage construction.
Tilt-up panels for the lower ancillary building at Airport West EES have been erected and grouting between the panels is ongoing. Up next is the installation of the roof structure.
What is a cross passage?
A cross passage is a short concrete tunnel which provides a link between two main tunnels, or a link between a tunnel and an EES. It takes up to three months to build each cross passage, which are up to 10 metres long and five metres high (around three metres high after final lining installation).
Of the 12 tunnel-to-tunnel and three tunnel-to-egress shaft cross passages located along the alignment, seven have now been completed.
Construction of the three cross passages that utilise the ground freezing method is nearing completion, with demobilisation of the ground freezing pipes underway.
More information about the ground freezing method is available on the Cross Passage fact sheet.