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 have been 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, plus additional time to build the supporting ground level infrastructure (ancillary buildings, forecourt 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.
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 emergency egress shaft. 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).