More than 66,000 commuters have piled onto Sydney's new driverless metro trains on average each weekday in their first two months of operation despite a spate of disruptions, figures show.

The weekday patronage in June and July makes the 36-kilometre Metro Northwest rail line from Chatswood to Rouse Hill in Sydney's north west almost as well used as the Eastern Suburbs line, the city's fourth busiest.

Patronage at Chatswood and Epping stations, which serve as interchanges for commuters, surged by 18 per cent in July, from the same month a year earlier, the statistics from Sydney Trains show.

Macquarie University students Rachel Dobbie, left, and Ellie Ryrie use the metro trains regularly. Credit:Dominic Lorrimer

Stations between the two interchanges, such as Macquarie Park and North Ryde, also had growth of 17 to 19 per cent in the number of commuters passing through in July, compared with the same month a year earlier when double-deck trains were operating.