RAIL ROUTE

TUNNELS

ENVIRONMENT

HERITAGE

PROGRESS

RAIL ROUTE

TUNNELS

ENVIRONMENT

HERITAGE

PROGRESS

Rail Route

The new Airport Line will separate from the Midland Line at ground level east of Bayswater Station. The line will descend below ground, passing under the city-bound Midland Line before running to High Wycombe through 8km-long twin-bored tunnels.

Bayswater Junction

Bayswater Junction refers to an area of rail reserve east of Bayswater Station where the Airport Line spurs off the existing Midland Line, and trains will enter and exit the tunnels. It includes a 400m-long dive structure that reaches a depth of 11 metres, a rail overpass for the city-bound Midland Line trains and a portal building which will house the controls for ongoing operation and maintenance of the tunnels.

Redcliffe Station

The 12m-deep underground station at Redcliffe is being built at the junction of Brearley Avenue and Dunreath Drive. The station will service the growing community, as well as the airport business park and direct factory outlet.

15-minute journey to CBD
1-zone fare to Perth Station
6-bay bus interchange
500 parking bays

Airport Central Station

With air passenger traffic more than doubling in the last decade, Perth Airport is undergoing a major redevelopment, which includes relocating and consolidating the domestic and international terminals. Airport Central Station will service this additional demand.

Located immediately south of the control tower and adjacent to Terminal 1, the 17m-deep underground station will soon change travel to and from the Perth Airport.

18-minute journey to CBD
2-zone fare to Perth Station
280m Skybridge to the terminals

High Wycombe Station

The above-ground High Wycombe Station, positioned alongside Dundas Road, will be a terminus station serving a large catchment area in Perth’s eastern suburbs and foothills.

20-minute journey to CBD
2-zone fare to Perth Station
8-bay bus interchange
1200 parking bays

Tunnels

Forrestfield-Airport Link will see a new rail line connect the railway east of Bayswater Junction to High Wycombe with 8.5 kilometres of new tracks, 8km of it in tunnels. Trains will enter the tunnels via what is known as a 'dive structure' before resurfacing next to Dundas Road in High Wycombe.

The catalyst for locating the rail service underground was the need to avoid disruption to aviation operations at Perth Airport, while also minimising impact on local residents and businesses. The new tunnels will be the longest in Perth and represent vital infrastructure that will connect the foothills to the suburban rail network.

World experience

Tunnelling is becoming a preferred innovative solution as cities around the world look to expand their transport networks. They are very useful in locations where above-ground options are exhausted and society places a high value on land at ground level.

Around the world, there are about 250 tunnel boring machines in operation, with about half of these in China and a further quarter in South East Asia.

Why tunnels work

Tunnels allow for effective, secure train operations and offer a viable alternative to an above-ground rail system. They save space and reduce cost.

They also reduce the potential environmental impact on existing residential and business areas, when compared to above-ground options.

Impacts and risks

Extensive engineering and environmental studies, and research into similar projects elsewhere, indicated that the chance of land disruption above the tunnels was minimal. It is also very unlikely there will be any impact to health or the environment, including homes or businesses, given the tunnels’ depth and method of construction. Even so, the PTA has strict protocols in place that require inspections to be conducted prior to any work taking place and has been in contact with residents and businesses adjacent to the tunnel route before, during and after tunnel construction.

Technical facts

The depth below ground level to the roof of the tunnels will vary between 7m and 25m. The internal tunnel diameter will be 6.2m — that’s big enough for a typical family car to fit sideways.
Tunnels will be built to specifications that enable them to withstand major environmental and manmade catastrophes.
Around the world, more than 2000 kilometres of tunnels run beneath cities, carrying trains and passengers every day.
Sydney’s suburban rail network is also being extended, with its North West Rail Project involving 15 kilometres of new bored tunnels.
The longest tunnel in the world is in Switzerland and is 54 kilometres in length.
Despite their huge electric- and hydraulic-powered motor drives, tunnel boring machines create little noise at the surface and cause only minor vibrations as they cut through the soil and rock in their path. Most people don’t even notice when the boring machine is directly under them.
Once the tunnel structures are complete it is unlikely you’ll even know the trains are there.

Environment

Environmental and heritage considerations are a key priority for the Forrestfield-Airport Link.

Studies undertaken by specialist consultants during the planning phase of the project have identified the following factors that require consideration:

Limiting the removal of native vegetation
Limiting any loss of fauna habitat
Managing disturbance of acid sulphate soils
Dewatering and groundwater quality
Managing existing soil and groundwater contamination
Managing noise and vibration
Preserving Aboriginal heritage
Managing waste.

The need to avoid areas of environmental and heritage value was incorporated into the concept design. Ongoing planning will seek to further reduce impacts to such areas.

Swan River

The trains will travel under the Swan River in twin-bored tunnels. Construction of the tunnels did not impact the river because the tunnelling process did not disturb the bed of the river or alter flows within the river. The PTA continues to consult with the Department of Parks and Wildlife (Swan River Trust) and will manage any potential impacts from non-tunnelled sections under the Swan and Canning River Management Act 2006.

Noise and Vibration

During construction, which started in 2016, the PTA will manage work in accordance with a project-specific Construction Noise and Vibration Management Plan and the Environmental Protection (Noise) Regulations 199.

Once the rail link is operational in late 2021, it is expected that there will be minimal impact from noise or vibration on surrounding areas due to the railway running primarily in tunnels. Design features, such as the use of noise barriers near surface rail, will be incorporated into the design to minimise potential impacts. A monitoring and complaints procedure will also be implemented once the rail line is operational.

Acid Sulphate Soils

Most of the material excavated to construct the tunnels is likely to be acid sulphate soil. Acid sulphate soils are naturally occurring soils that are benign in an undisturbed state. If not managed appropriately, though, disturbance of acid sulphate soils can result in the release of sulphuric acid and heavy metals, which have the potential to pollute groundwater, watercourses and wetlands.

A site investigation was undertaken to allow the PTA to assess risks associated with construction and operation of the rail line and to develop appropriate management and mitigation measures to protect the community and the environment.

All work is undertaken in accordance with the Department of Environment Regulation (DER) Contaminated Sites guidelines. Further, a DER approved contaminated sites auditor has been appointed by the PTA to independently audit the investigations. Consultation has been, and will continue to be, undertaken with the DER’s Contaminated Sites Branch and the Department of Health.

Dewatering

Temporary lowering of the groundwater table was required to construct the underground structures. Dewatering activities have the potential to mobilise existing groundwater contamination and cause a decline in vegetation and wetland health and function. Importantly, no dewatering was required to construct the tunnels.

A Dewatering Management Plan was prepared to ensure no adverse impacts to the surrounding environment resulted from the dewatering activities. An extensive groundwater-monitoring program was implemented prior to, during and following completion of construction.

Clearing

Construction of the Forrestfield-Airport Link will require clearing of small patches of native vegetation. Clearing of these areas was managed in accordance with the requirements of the Environment Protection and Biodiversity Conservation Act 1999 and the Environmental Protection Act 1986. Where significant impacts were predicted, environmental offsets were provided by the PTA.

Heritage

Aboriginal heritage is very important to the Forrestfield-Airport Link project and has been a key element of the planning and early design phase leading up to construction in 2016. It remains a pivotal component of the ongoing engagement process.

The Forrestfield-Airport Link project acknowledges the importance of Noongar culture and knowledge in preserving connection to country and cultural heritage within the project footprint.

Swan River

Impacts to the spiritual significance of the river to the Noongar people are acknowledged by the PTA.

Poison Gully

PTA recognises the significance of Poison Gully Creek due to its Aboriginal heritage and environmental values.

The bushland was identified for retention as part of the Project’s early design process due to the presence of rare flora, habitat for protected fauna and its Aboriginal heritage significance.

Management measures such as fencing were adopted during construction to avoid impacts to the Poison Gully Creek bushland.

Access to the bushland will however be maintained at all times during construction.

Munday Swamp

The rail lines will travel to the south of Munday Swamp in twinbored tunnels. Construction of the tunnels did not impact Munday Swamp because the tunnelling process did not disturb the groundwater level or quality.

Noongar Whadjuk Nation Land

The Forrestfield-Airport Link project acknowledges the importance of Whadjuk culture and knowledge in preserving connection to country and cultural heritage within the project footprint.