The Thornlie-Cockburn Link and Yanchep Rail Extension have reached an important milestone, with the introduction of enabling legislation to State Parliament.

The Railway (METRONET) Bill 2018 will authorise the rail infrastructure construction for these two projects, which will add significant capacity to Perth's public transport network. Upon enactment, construction can begin.

The 17.5 kilometre Thornlie-Cockburn Link will be Perth's first east-west rail connection by linking Thornlie Station to Cockburn Central Station on the Mandurah Line.

The project includes relocating the existing freight lines and building two new stations at Nicholson and Ranford roads.

When operational, it will be a 25-27 minute journey to Perth from Nicholson Road and a 28-30 minute journey to Perth from Ranford Road.

The enabling act also authorises the Yanchep Rail Extension - a project to extend the Joondalup Line from north of Butler Station and construct three new stations at Alkimos, Eglinton and Yanchep.

The Project Definition Plans for both projects will be finalised soon, with construction planned to start next year.