Passengers 'jolted' as new light rail tram heads down wrong line

"Driver error" has been blamed for a hiccup on Sydney's new light rail service that saw a tram head down the wrong line.

Travellers were today welcomed aboard the new rail service from Circular Quay to Randwick for the first time.

Large crowds were expected when the long-awaited tram service opened to the public on the new route from 11am today.

No fares will be charged during the opening weekend of the $2.9 billion project, which has been plagued by cost blow-outs and significant delays.

9News reporter Airlie Walsh tweeted that the service had experienced its first "hiccup" after passengers were jolted when the tram braked hard pulling into a Randwick stop, before reversing.

The service confirmed the incident was due to driver error.

All up, the full trip along the line took 58 minutes door-to-door, which Walsh said was about 30 minutes longer than catching a bus between Randwick and Circular Quay.

The service has advised the longer travel times are to be expected while the network "beds down" over the next few months.

The branch line to Kingsford isn't expected to open until early next year.

Additional staff will be on hand throughout the weekend, while traffic controllers and police officers will be on the ground to deal with higher than normal numbers of commuters.

Extra buses will be running from Randwick into the city.

NSW Transport Minister Andrew Constance said it will be an exciting day for Sydney, but warned people to be patient amid large crowds and remain safety conscious while travelling, driving or walking in the city.

A coupled tram holds up to 450 passengers, the equivalent of nine buses.

Some 200,000 kilometres of tram testing has already taken place while the 100 drivers have each undertaken 190 hours of training.

The new network will move up to 13,500 commuters an hour during peak time in both directions, the state government said.