The Airport line was originally planned to open in 2020, but that was delayed several times due to the aforementioned problems and later supply chain issues caused by the COVID-19 pandemic.

[3] Following the 2008 state election, the new Liberal government withdrew the application to Infrastructure Australia,[3] with Premier Colin Barnett saying that he believed airport rail links were not viable in cities the size and density of Perth.

[6][7] In December 2012, the Labor opposition announced its Metronet plan to rapidly expand Perth's rail network, which it would take to the 2013 state election in March.

By the end of 2013, Transport Minister Troy Buswell said he was considering making the Airport line entirely underground from Bayswater to High Wycombe as it could be better value for money.

Transport expert Peter Newman and Opposition Leader Mark McGowan criticised the idea of building the line entirely underground, saying it would be far more expensive.

[16][17][18][19] The Forrestfield–Airport Link involved building twin-bored 8.5-kilometre (5.3 mi) tunnels from the Midland line at Bayswater to High Wycombe, passing under the Swan River and Perth Airport.

Bored tunnels were chosen as they reduced disruption at ground level during construction and result in less land being taken up by rail infrastructure.

The Forrestfield–Airport Link is the second time that tunnel boring machines (TBMs) were used in Western Australia, the first being the construction of the Mandurah line under the Perth central business district in the mid-2000s.

[36][37] SI-NRW Joint Venture was selected as the preferred proponent in February 2016,[38][39] and in April 2016, the contract was signed at a cost of $1.176 billion.

She also criticised the former government for not including a turnback siding at Claremont or significant upgrades to Bayswater station in the project's budget.

[88] In September 2018, a leak developed during the construction of a cross passage between the two tunnels which caused a sinkhole underneath Dundas Road, about 200 metres (660 ft) north Forrestfield station.

The chosen permanent solution was for spheroidal graphite iron rings to be placed inside the damaged tunnel area to brace it.

[92] On 18 December 2018, state Transport Minister Rita Saffioti announced that the opening of the Forrestfield–Airport Link had been delayed by one year to 2021 due to the sinkhole, as well as the TBMs moving slower than expected and an increased rate of safety stoppages.

[109][110] In February and March 2021, two shutdowns of the Midland line took place to connect the Forrestfield–Airport Link to the rest of the rail network.

[113] In October 2017, a worker at Bayswater junction suffered an electric shock when a crane hit high-voltage power lines.

[118] In July 2018, a worker was knocked unconscious after being struck in the head by a high pressure air hose at Airport Central station.

[132] In September 2022, the United Professional Firefighters Union expressed concern that the Airport line's opening was being rushed.

[133] In 2017, it was publicised that groundwater and soil underneath Perth Airport was contaminated with perfluoroalkyl and polyfluoroalkyl substances (PFAS), which are toxic chemicals formerly used in firefighting foam.

[136][137] The state wanted to reuse the contaminated soil on the future third runway project at Perth Airport,[138] but the federal government rejected that proposal.

[139][140] As of March 2023, some of the contaminated soil has been used on the Great Eastern Highway Bypass upgrade, with the rest to be used on future infrastructure projects.

[141] In July 2021, SI-NRW JV commenced legal action against GHD Group, alleging it was negligent in failing to prepare an adequate design concept.

[142] In particular, SI-NRW JV alleged that GHD breached the tender design agreement for the twelve cross passages and three stations, causing the joint venture to suffer a $17.5 million loss.

[155] The original Forrestfield–Airport Link plan only called for $7 million to be spent on minor upgrades to Bayswater station to bring it into compliance with the Disability Discrimination Act 1992.

Rebuilding underground was ruled out due to various factors, including high cost and disruption, low benefit, and constraints created by the already under construction Forrestfield–Airport Link.

Replacing the level crossing with a bridge or underpass was considered, but those options were eliminated as they would require the demolition of several houses.

[179] An interview with Saffioti released on 3 April 2022 had the minister reiterate the intention to have the line open by the end of June 2022.

[183][184] A report by the Auditor General of Western Australia released in June 2022 criticised the government for its lack of transparency for major projects, including the Forrestfield–Airport Link.

[198][199] The Airport line branch uses 1,067 mm (3 ft 6 in) narrow gauge track[199] and has a maximum speed of 130 kilometres per hour (81 mph).

Factors limiting accessibility include non-compliant ramps, a lack of tactile paving, large platform gaps, and pedestrian level crossings.

[219] However, the operating hours later revealed had the first train depart Perth bound for High Wycombe at 5:12 am on weekdays, 5:45 on Saturdays, and 7:08 am on Sundays and public holidays.