Sydney Trains will cancel 36 mostly peak-hour services on Monday due to staff shortages, as its annual reports show the number of train crew on the city's rail network has barely budged over the past four years despite a surge in patronage.

The cancellations on Monday come after the rail operator cancelled 92 services on Saturday due to "unexpected train crew changes", including 44 on the T1 Northern, North Shore and Western Line.

Underscoring the challenges for front-line workers in dealing with "a massive increase" in patronage, the reports reveal the number of station staff has fallen by a quarter since Sydney Trains' first year of operation in 2013 when it replaced Railcorp.

Severe disruptions across the city's rail network last week revealed how Sydney Trains had been caught short by a lack of drivers to cope with an increase in services as a result of a new timetable. That timetable has reduced the ability of the system to recover from delays caused by major incidents.