The next stage, replacing the old-style hydraulic lift with a new, wider-door electric model, should be finished by early next year.
The work is part of a $7.1 million, two-year project to replace escalators and lifts at five stations on the Joondalup line.
Public Transport Authority spokesman David Hynes said Warwick station had only one working escalator, while the other was replaced.
However, passengers could use the lift, ramp or stairs to get to the platform.
Mr Hynes said the new escalators’ soft-start meant they would slow when not in use and increase to normal operating speed as people approached and got on.
‘They will also be cheaper to operate, easier for people to use and better for the environment,’ he said.
‘The two new escalators are reversible, which means if one is out of action for repairs or maintenance, the direction of the second escalator can be changed to match peak flow while work on the other is carried out.’
Whitfords is the next station earmarked for upgrade work and there will also be upgrades at Joondalup, Stirling and Glendalough stations.