A computer glitch at Homebush station is thought to be the reason behind a horror night on nearly every Sydney train line.
Thousands of commuters were left stranded at stations around the city with delays and cancellations on the T1, T2, T3 and T5 lines as well as the Central Coast and Newcastle lines.
Substitute buses were brought in to manage the backlog of commuters, however some still faced delays spanning hours.
While the problem has since been corrected, the knock on effect was felt for hours.
Rail bosses say they are confident services will be running on time by Wednesday morning.
Routes between Hornsby and Berowra, Blacktown and Richmond, Penrith and Emu Plains and between Campbelltown and McArthur experienced the brunt of the delays.
Those waiting to get home were less than impressed.
“It's quite annoying, I would have liked to have left work early because I have something on tonight so no doubt I’ll be late now,” one woman told 7 News.