The route for the Airport Line 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 High Wycombe.
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 upper ancillary building – the building erected on top of the shaft – has been fully installed. Fit-out of the shaft is well underway, and earthworks at the are compound focussed around the second layer of limstone.
Crews are working on finalising the stair and lift shaft installation at Airport West EES. Above ground, air conditioning and refrigeration pipe installation within the lower ancillary building is underway, following the completion of the building's roof sheeting.
Wright Crescent EES holds third place with the building structure adjacent to the shaft in place. The upper building will be erected following the installation of the lift frame and stairs within the shaft. The second cross passage, connecting the shaft and Tunnel Two, will be excavated from within the tunnel, with the diaphragm wall inside the shaft already cut.
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, 10 have now been completed.
Activity relating to cross passage construction is primarily taking place along the 2.5km-long stretch of tunnel between Redcliffe Station and Bayswater Junction. Four of five tunnel-to-tunnel cross passages in this section have been fully excavated, along with the link between Wright Crescent Emergency Egress Shaft (EES) and Tunnel One. All soil will be carted out via the Bayswater portal now that the TBMs have been removed.