Sydney trains on track after Sunday chaos

Four hundred engineers have worked overnight to ensure Sydney commuters can get to work on time on Monday, the head of the city's train network says.

It follows a day of rail chaos on Sunday after an upgrade to a 39-year-old signalling system took longer than expected, leaving some commuters waiting up to three hours.

Sydney Trains chief executive Howard Collins says compensation will be considered for passengers caught up in the delays.

"Big apologies for yesterday. This was a major heart surgery on our entire signalling system," Mr Collins told Seven Network on Monday.

"I met some customers who missed out on their holiday. There were three or four trains stuck outside Sydney for a period of time. We have reached out to those people," he said.

" I want to say sorry and at least give them a gesture of goodwill to let them know we understand and this is not going to happen every Sunday. It is a once-in-a-lifetime change."

Mr Collins said trains were running as normal on Monday.

However, several trains were cancelled on the T1 North Shore, Northern and Western line due to operational issues.