Improved Connectivity for Perth
The Forrestfield Airport Link directly connects the international airport and the eastern suburbs to public transport, alleviating congestion on the existing network.
Client
TREVI S.p.a.
Location
Perth, Australia
Priorities
Connect with an expert
Sven Kessler
Forrest Airport Link - Innovative Tunnel Construction Solutions for Perth
The existing transport infrastructure in Perth is being relieved by a direct connection to the airport. The project combines complex tunnelling works, innovative ground engineering techniques, and precise geotechnical laboratory investigations — all to ensure the highest level of safety.
Tunnelling Beneath the Airport
Two parallel tunnel tubes run partially beneath sensitive airport infrastructure, requiring meticulous planning and execution.
Ground Freezing for Maximum Safety
Cross passages were excavated under the protection of ground freezing to minimize settlement and ensure safe tunnelling.
Geotechnical Laboratory
Our geotechnical laboratory provided key insights from soil samples, delivering temperature and stability data to enable safe and controlled tunnel construction.
Expansion of Public Transport in Perth
The Western Australian Government determined the expansion of the East-West-Link to optimize public transport in the city of Perth. The new 8.5 km long line “Forrest Field Airport Link” enhances the Eastern suburbs’ and the international airport’s connection to public transport while relieving the existing infrastructure and creating three new stations: Redcliffe, Airport Central and High Wycombe.
Implementation of the Tunnel Section
This new line consists of two twin-bored tunnels, connected by a total of 12 cross passages. In order to avoid surface deformation in the airport area, three cross passages were mined under favor of ground freezing. At our geotechnical laboratory, we executed freezing tests with the Australian ground samples from which we determined thermotechnical and static parameters for the frost body sizing. As the cross passages would be located right underneath the runway, particular attention was turned to frost heave tests. These parameters formed the basis for our numeric design engineering regarding heat calculation, frost body statics and surface deformation. Through our heat calculations we ensured a temperature of T ≤ 0°C in the area of the maximum dimensions of the cross passages’ centres near the tunnel ridges to prevent material from advancing during excavation. Thereby ensuring safe tunnelling. Owing to our thermotechnical calculations we were able to deviate the frost body’s dimensions as well as provide evidence of its sufficient performance.
We calculated the statics numerally for a freezing period of six weeks. Taking also into consideration the frozen frost body’s thicknesses derived from our thermotechnical calculations. For the decisive cross-sectional area adjoining the tunnel lining, we also preconceived the sufficient structural stability of the frozen frost body’s thickness with 1.5 metres. We were able to provide evidence for the frost body statics with safety factor 2 and 4 for this cross-section consideration. As the cross passages are located underneath very sensitive areas as the Forrestfield Airport, surface deformations were limited to 1.5 cm at most. We verified complying with these deformation limits by means of bivariate numeric calculations of frost heave. Additionally, we evaluated temperature measuring data during execution, and monitored approval and opening of the cross passages by our experts on site. Train service is already operating on this new airport line.
Client
TREVI S.p.a.
Location
Perth, Australia
Priorities
Connect with an expert
Sven Kessler
Project Figures
26 m
below Swan River
7 m
Tunnel diameter
Works took place under challenging conditions as the tunnel boring machines had to cross underground Swan River as well as Perth’s Airport, with air traffic ongoing. For these reasons we decided for ground freezing, as only a mining technique could comply with the requirements to surface deformation.
Rudolf Wernecke
Senior Project Manager
Project Contacts
Have questions about the project or our services? Our experts are happy to help.
Sven Kessler
Project Manager
Sven Kessler is an expert in Artificial Ground Freezing, supporting complex geotechnical projects with extensive technical expertise. His experience also covers specialised foundation engineering, foundations and ground improvement.