Yanchep line

The Yanchep line, formerly the Joondalup line, is a suburban railway line in Perth, Western Australia, linking the city's central business district (CBD) with its northern suburbs. Operated by the Public Transport Authority as part of the Transperth system, the Yanchep line is 54.5 kilometres (33.9 mi) long and has sixteen stations. It commences in a tunnel under the Perth CBD as a through service with the Mandurah line. North of there, the line enters the median strip of the Mitchell Freeway, where nine of the line's stations are. The Yanchep line diverges from the freeway to serve Joondalup and leaves the freeway at Butler for the northernmost four stations to Yanchep.

Planning began in 1987; after several transport modes were considered, including bus rapid transit, an electric railway was chosen. Known during construction as the Northern Suburbs Railway, the project was approved by the state cabinet in 1989 and construction began in November 1989. The line was built under multiple contracts totalling A$277 million. It used widely spaced stations with bus interchanges and large park-and-rides, distinguishing the line from Perth's three existing rail lines. The Joondalup line opened on 20 December 1992 to limited service and with three new stations: Leederville, Edgewater and Joondalup. Four more stations opened in February 1993, and on 21 March 1993, peak service and feeder bus routes commenced. The final station, Currambine, opened in August 1993.

An extension north to Clarkson station and rebuild of Currambine station opened in October 2004, and in January 2005, Greenwood opened as an infill station. The Joondalup line originally through-ran with the Armadale line via Perth station, but in August 2005, the line was terminated at Perth station, and in October 2007 the line was rerouted through a new tunnel under the CBD, with two new stations: Perth Underground and Elizabeth Quay. The Mandurah line opened in December 2007 to connect with the southern end of that tunnel. An extension north to Butler station opened in September 2014 and a three-station extension north to Yanchep station opened in July 2024, upon which the line became the Yanchep line.

B-series and C-series trains are the main rolling stock used on the Yanchep line. Trains run at a fifteen-minute headway, reducing to as low as a five-minute headway in peak, with some services terminating at Whitfords or Clarkson stations during peak. The travel time from Yanchep to Perth Underground is 49 minutes. The Yanchep line received 16,614,973 boardings in the 2024–25 financial year, making it the second busiest line in the Transperth system, after the Mandurah line.