The Armadale line is a partially-closed suburban railway service in Perth, Western Australia, operated by the Public Transport Authority as part of the Transperth system.

The Armadale line is 30.4 kilometres (18.9 mi) long, and starts at Perth station, heading south-east of there to serve Perth's south-eastern suburbs, terminating at Armadale station.

Since November 2023, the line has been closed from Victoria Park station to Armadale for the Victoria Park-Canning Level Crossing Removal Project, the Rail Revitalisation Program and Byford extension.

The Armadale line originated from suburban services along the South Western Railway in the 1890s.

Suburban services were extended over the first half of the 20th century to eventually reach Armadale station.

[1] Initially, the railway had a limited passenger service, run by mixed trains.

Kelmscott and Armadale were considered to be country towns, and were served by the daily train to and from Bunbury.

The Armadale line was electrified in the early 1990s, with the electric Transperth A-series trains entering service in September 1991.

As part of New MetroRail in the 2000s, Carlisle and Victoria Park stations were upgraded, Lathlain station was closed on 3 February 2003, and the Miller Street bridge in Lathlain and the Gerard Street bridge in East Cannington were built to replace level crossings.

[5][16] A weekend service was added in 2018 and trains began stopping seven days a week from 2 April 2024.

[18] Also occurring as part of Metronet is an extension of the Armadale line south to Byford.

[20] In February 2022, it was announced that an 18-month-long shutdown of the Armadale line would have to occur to construct the Victoria Park-Canning Level Crossing Removal Project and the Byford extension.

[24][25] The shutdown, which closed the line between Victoria Park and Armadale stations, commenced on 20 November 2023 and is expected to end by mid-2025.

[28] The Armadale line uses 1,067 mm (3 ft 6 in) narrow gauge track[29] and has a maximum speed of 100 kilometres per hour (62 mph).

[31][32] As of 2021, the CBTC system is planned to be implemented on the Armadale and Thornlie lines by June 2031.