No trains will be running at Sydney Airport's domestic and international stations this weekend, as lines across the network undergo "essential trackwork".
Replacement buses will be running between Glenfield and Sydenham and between Sydenham and Central, including the airport stations, as part of the Rail Repair Plan.
The works will begin just before midnight on Friday and run until the first service on Monday morning.
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The T2, T4 and T5 lines will also be affected.
Transport for NSW is urging commuters to allow extra time this weekend.
Below is what we know about the works.
T2
On the T2 Inner West and Leppington line, buses will replace trains between Leppington and Glenfield, and between Ashfield and Central Stations.
Trains will also run to a changed timetable between Macarthur, Glenfield and Central via Granville due to the trackwork.
T5
Buses replace trains between Leppington and Glenfield on the T5 Cumberland Line as well.
Trains run to a normal timetable between Liverpool and Schofields.
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T4
In the city, City Circle stations at Museum, St James and Circular Quay will be closed, but trains will continue to run between Central, Town Hall and Wynyard while T4 Eastern Suburbs trains will still run to Martin Place.
Light rail services will be operating as normal in the city.
T8
Buses will replace scheduled train services on the T8 Line between Glenfield and Sydenham and between Sydenham and Central, including the Domestic and International Airport Stations.
Buses will also replace trains from North Sydney between Tallawong and Epping as part of metro upgrades.
About 1500 track workers across 200 sites will be fixing the "high-priority" defects.
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