The depot features nine roads under the main shed (numbered 1-3 and 5–10), two elevated outdoor roads (numbered 11 and 12), a train washing facility and several short outdoor storage sidings.

They are responsible for the amalgamation and division of the Tangara sets to facilitate maintenance and repairs.

The shunters are also responsible for the safe passage of trains, staff and other equipment within the facility.

[2] Following the opening of the Eastern Suburbs line in 1979, Mortdale became the first all double deck depot, only having S sets allocated to it.

In 2020 plans are being prepared to upgrade the depot to increase its maintenance capacity, in preparation for increased services on the Illawara line as part of the Transport for NSW's More Trains, More Services program.