Sydney's new metro stations open after two years of disruption

The Southwest Metro has finally opened to Sydney commuters.

Public transport enthusiasts, early commuters, politicians and other officials were aboard the first 13-kilometre passenger service from Bankstown to Sydenham, which pulled in at 4:31am.

It comes after more than two years of passengers being forced onto replacement pink buses to allow for the 130-year-old heavy rail T3 Bankstown line to be converted into a metro line.

The city and south-west line has been plagued by cost blowouts with the final cost just under $23 billion, while the Sydenham to Bankstown extension took more than a year longer than initially forecast.

The 10 stops along the line from Marrickville to Bankstown have been completely transformed, with the installation of automatic glass platform doors and the upgrading of tracks and corridors.

The national safety regulator has required that six platform and train doors at stations along the route, at Dulwich Hill, Canterbury, Campsie and Marrickville, remain closed because of concerns about wide gaps at curved platforms and the mechanical gap-fillers, pending further checks.

"It's clearly signposted so there's going to be no confusion," Transport Minister John Graham said.

Mr Graham said testing had otherwise gone well, with reliability improving and performance better than on the heavy rail network.

Commuters can expect services to run every four minutes during weekday peak hours and every five minutes outside of that.

On weekends and evenings, services will operate every 10 minutes.

The promised faster journey will save commuters travelling from Lakemba to Victoria Cross up to 24 minutes in travel time, while the journey from Marrickville to Gadigal is expected to be halved to 12 minutes.

Progya Das, who commutes from Bankstown to Pyrmont for work, said she was looking forward to enjoying a bit more sleep in the morning and the faster commute.

"It takes me one and a half hours … I checked the schedule, it's probably going to cut me half an hour," Ms Das said.

"The news that the metro is opening, it's very exciting."

She said she would not miss the pink buses, although she admitted they had been running on a good schedule every day.

"I feel like the metro is going to be so much quicker," Ms Das said.

Sujan Sharma, who travels from Campsie to Gadigal station daily, said he would be able to spend more time with his children by helping with the school drop-off in the morning and preparing dinner in the evening.

"I can see the commute time is already all the way down to 20 minutes," Mr Sharma said.

The new metro will increase capacity by 50 per cent compared to the old T3 line, the government said.