Commuters in Perth's eastern suburbs are being warned to allow extra travel time when the Public Transport Authority (PTA) shuts down the Armadale and Thornlie lines for nine days.

The shutdown commences on Friday evening and train services will recommence on Sunday, July 10.

David Hynes, the PTA's manager of corporate communications, told 720 ABC Perth the shutdown was necessary for works on the new station for the Perth Stadium at Burswood.

"Work on the station started about a year ago and we have reached the stage where four of the six platforms have been built and we now need to shift the railway line so that we can build the last two, so that's what's happening over the nine days," Mr Hynes said.

The Armadale line and its branch line to Thornlie will be rerouted through the new station during the shutdown.

Passengers warned to prepare

Mr Hynes said the PTA recognised the shutdown would be inconvenient for regular users of the line but said the authority was working hard to publicise it so passengers could prepare.

"There will be replacement buses that run up and down along the railway line and pick up people as close to stations as they can," he said.

"We make our best efforts to replace the train with a bus. It's not quite the same because they are not as big and they are subject to traffic conditions.

"Depending on how far you are travelling, you will need to allow up to 45 minutes' extra travelling time."

The replacement bus services will commence and terminate at Claisebrook station in East Perth. Passengers will then have to transfer to train or CAT bus to continue into the CBD.

The publicity material for the closure also suggests people could try to work from home, alter their work hours, travel by bicycle or take holidays, although Mr Hynes conceded "there are some people who can't".

Commuters are advised to take note of the changed conditions and be prepared. ( 720 ABC Perth: Emma Wynne )

'Long-term gain from commuter pain'

Mr Hynes said timing of the shutdown had been carefully planned to reduce disruption.

"That's not a coincidence that we are doing it over a school holiday period when there is less pressure on," he said.

"It doesn't affect any AFL games and we are only affecting five working days of the nine days that it is closed.

"It is a nuisance but there is a terrific result at the end of it. [The new station] will be one of the best special events stations in Australia."

Shutdown information and bus replacement timetables are available online from Transperth.