The AU$26m contract is for the upgrade of the T3 Bankstown Line between Sydenham and Bankstown.
The Metron T2M joint venture will deliver design services for the stations and the railway corridor between Marrickville and Punchbowl.
The metro upgrade will result in all 11 stations being be fully accessible, including delivering lifts for the first time at five stations and configuring platforms to be level with train doors.
Corridor works will include the design of cabling systems, track, upgrades to bridges including anti-throw screens, retaining walls and security fencing along the corridor.
From 2024, customers using the upgraded Bankstown Line stations will get 15 trains an hour during the peak in each direction. Some stations currently get as few as four trains an hour in the peak.
Survey work and geotechnical investigations are already taking place within the rail corridor.