Gabby Fernandez's daily commute from the St George area in Sydney's south to Macquarie University in the north usually takes her 90 minutes.

After the Epping-to-Chatswood rail line is closed on Sunday for seven months, she expects it to take her at least two hours because she will have to switch from train to bus at St Leonards.

Arts student Gabby Fernandez expects her journey time from St George to Macquarie University to increase significantly. Credit:Nick Moir

“I'm not going to drive. Parking here is a nightmare,” the first-year arts student said.

The temporary shutdown to allow the line to be converted to carry single-deck metro trains will be the biggest jolt to Sydney's transport network since new bus timetables and routes in the CBD were put in place in 2015 ahead of the construction of the $2.1 billion light rail line.