A driverless train which broke down on Sydney's new Metro line had to be moved to the next station by a so-called "customer journey coordinator".
Transport for NSW blamed Wednesday afternoon's glitch on a communication fault on a train between Epping and Cherrybrook stations as it was heading towards Tallawong.
Essentially the driverless train stopped communicating with the system, a TfNSW spokesman said in a statement.
The train was then driven to Cherrybrook station "under the control of a customer journey coordinator". A technician was also sent to investigate.
The troubled train remained in operation and customers continued their journey to Tallawong.
It was then returned to the depot for checks and a replacement train was sent out.
"One train, one glitch, and rectified within 25 minutes, that's the good news," Transport Minister Andrew Constance told Seven News.
The Transport for NSW spokesman said: "While there were some delays as a result of the incident services are returning to normal with 16 trains expected to be operating in the system for the afternoon peak."
Normal train services were planned for the rest of Wednesday evening.
The Metro northwest line opened on Sunday with just under 140,000 people taking advantage of free trips on the day.
Monday saw some 66,008 customer trips and on Tuesday there were 72,401 trips.
More than 20,000 people worked on the $7.3 billion project over eight years, and work is now underway to extend the line from Chatswood to Bankstown.
Later, another Metro project will link greater Parramatta with the CBD.
Australian Associated Press
Sign up for our newsletter to stay up to date.