Joondalup line

The Joondalup line is a commuter rail service in Western Australia, linking the Perth central business district (CBD) with the metropolitan area's north-western suburbs. The service is operated on the Northern Suburbs Railway by Transperth Train Operations, a division of the Public Transport Authority, and is part of the Transperth network. It is 40.7 kilometres (25.3 mi) long and serves 13 stations. The service is currently being extended to Yanchep as part of the Yanchep Rail Extension project.

Construction of the infrastructure for the service began on 14 November 1989. It opened between Perth station and Joondalup station on 20 December 1992, albeit with only Perth, Leederville, Edgewater and Joondalup stations operational. The remaining stations began operating on 21 March 1993. The Joondalup line initially continued as the Armadale line. The service has been extended beyond the original terminus at Joondalup several times since: an extension to Currambine opened on 8 August 1993; an extension to Clarkson opened on 4 October 2004; and an extension to Butler station opened on 21 September 2014. The railway for the service has also been realigned through the Perth CBD, as part of the construction of the Mandurah line: on 15 October 2007, the southern end began operating through tunnels under the CBD, terminating at Elizabeth Quay; and on 24 December 2007, the service began to through-run south as the Mandurah line service. In 2019, work commenced to extend the service to Yanchep as part of the Yanchep Rail Extension project, scheduled to be completed by early 2024.

Trains take 38 minutes to get from Perth Underground station to Butler station. The service is the second busiest on the Transperth network, with 14,045,991 boardings in the 2022–23 financial year. Headways are at least every 15 minutes during the day, rising to every 5 minutes on parts during peak time.