Commuters have been wrongly told to get off trains and look for bus services that didn't exist as a technical glitch marred the start of a suburban line's seven-month closure.
Buses began replacing trains on Sunday morning between Chatswood and Epping as the underground rail line is prepared for the new single-deck Metro North West rapid link scheduled to start between March and June 2019.
Most of it went without a hitch.
But automated messages on some trains operated on a weekday timetable, not the weekend one, and instructed some passengers to get off at St Leonards or Beecroft for a replacement bus.
Services from those stations only run on weekdays.
"We've now put buses there to make sure we pick up anybody left by this little customer information glitch," Transport for NSW co-ordinator General Marg Prendergast told reporters on Sunday.
"That's why we (start the shutdown) on a Sunday, we anticipate a few problems. We're on the case."
Ms Prendergast said other services were running smoothly.
It comes little more than a month after technical issues caused network-wide issues on Sydney trains for more than 24 hours.
Transport Minister Andrew Constance said the latest glitch was a very small element of a very large IT system.
"The message is: rely on our staff," he said.
"We've all become so reliant on our technology."
Mr Constance urged road and rail commuters in the area to allow more time for their travel.
With up to 110 train replacement buses on the roads each day, the roads authority has installed more monitoring along key roads and hired more tow trucks to clear breakdowns.
