After being planned and talked about for years, Jakarta's airport rail link has finally opened.

The train links Jakarta city centre to the main international airport, Soekarno-Hatta, more than 30km to the west, and aims to spare travellers from the city's notorious traffic jams.

The new service, which takes 55 minutes, has quickly proven a hit, not only with air travellers but also with families trying out the train for fun.

At least half of the passengers using the new train service last Thursday, during its trial period from Dec 26 until tomorrow, were those coming in groups testing a quick round trip. They spent time in the cafes or restaurants at the airport's departure hall before heading back to the city centre.

Among those trying the new service was retired military officer Edi Sitorus, 63, who was in a group of six that included his grandson and in-laws. "It's comfortable and punctual... (but) the ticket fare is expensive," Mr Edi told The Sunday Times.

He compared the 70,000 rupiah (S$7) airport train ticket with the 40,000 rupiah charged by the airport bus service, which allows passengers to conveniently choose to alight at many places spread out across Jakarta.

"Bus trips would only require you to continue the trip with a short taxi ride."

The airport train, called Railink, has a nice and sleek toilet like that on a plane, said Mr Reynald, 28, a college student and part-time Mandarin Hotel Jakarta employee.

He was trying out the train service with his mother and two aunts.

"The process to get tickets was quick and smooth. We used one of the vending machines. They work similarly to an ATM, only that you swipe your card after you make your choices on the screen," Mr Reynald, who goes by only one name, told The Sunday Times.

Passengers may select the name of the station they want to travel to by pressing its location on the map.

For now, however, Railink stops only at the airport, at Sudirman Baru station, located in the heart of Jakarta, and at two other stations, Duri and Batu Ceper, closer to the airport. The service will be extended to Manggarai station in South Jakarta in 2019.

Passengers may also buy tickets via a Railink appfrom the Google Play Store or Apple App Store.

After the ticket purchase, a barcode will be sent in an e-mail attachment, which passengers can download on their mobile phone. They can then tap it on the electronic gate as they enter and leave the station.

Starting on Jan 2, Railink will have a total of 82 trips every day.

The train is connected to the Skytrain that takes passengers to all terminals at the airport.

Early next year, President Joko Widodo will inaugurate Railink, a project that was backed by the previous administration but never implemented.

Feeder buses also started operations last Thursday, connecting the Sudirman Baru station to several spots in the city, including Gambir, the main inter-city train station in Jakarta.