KAI Commuter Tests 12-Car SF12 Trains on Green Line to Boost Capacity

Reaching 160 percent of normal capacity during peak hours, the Tanah Abang-Rangkasbitung commuter line began a limited weekend trial of 12-car trainsets on November 14 to ease severe overcrowding.

Passenger volumes on the route, known as the Green Line, climbed to a daily average of 190,263 users over the weekends in October, according to KAI Commuter data cited by detikNews. That figure represents a 3.85 percent increase compared to the daily weekend average of 183,589 users recorded in September.

To address the crowding, PT Kereta Api Indonesia began testing formations of 12 coaches, known as SF12, across six specific trips between Tanah Abang and Parung Panjang. The test runs operate only from the afternoon through the night on November 14 and 15.

“Uji coba layanan ini sementara hanya melayani pada perjalanan mulai siang hingga malam di akhir minggu saja,” said Purnomo Sidi, Direktur Utama KAI Commuter, in a statement reported by detikNews on November 14.

While the weekend trial tests passenger flow and station readiness, running 12-car trains permanently on the Green Line requires significant electrical and signaling overhauls. PT Kereta Api Indonesia (Persero) or KAI said that the route currently relies on 8-car and 10-car formations because existing electrical substations cannot support longer trains.

Route occupancy during rush hour has surged past normal thresholds, according to KAI leadership. “Green line itu sekarang sudah lewat dari AW4. AW4 itu kalau jam sibuk sudah 160 persen kapasitasnya,” said Bobby Rasyidin, Direktur Utama KAI, as reported by CNN Indonesia on November 10.

To resolve the power constraints, KAI scheduled the construction of four new traction substations along the Green Line starting in December. The electrical work will take roughly six to seven months to complete, clearing the path for full SF12 operations on the Green Line, according to KAI.

A second phase focused on upgrading signaling systems is projected to begin in late 2027 and wrap up by the end of 2028. This modernization will shorten headways between arriving trains, allowing the newly procured domestic trainsets from PT Industri Kereta Api (Persero) to run at optimal frequencies.

The current weekend assessment serves to evaluate platform clearances and passenger management before full implementation. Karina Amanda, Corporate Secretary KAI Commuter, pointed out that the steady climb in weekend ridership makes capacity expansion urgent for the Rangkasbitung corridor.

The trial schedule features six designated departures operating on a round-trip basis between Parung Panjang and Tanah Abang. The first test run departed from Parung Panjang at 14:45 WIB under train number 1733, while the final scheduled test run leaves Tanah Abang at 20:39 WIB under train number 1788, as detailed by JournalArta.

“KAI Commuter akan terus lakukan evaluasi atas uji coba layanan SF12 kepada pengguna ini untuk nantinya pemberlakuan layanan full SF12 pada lintas tersebut,” said Purnomo, as recorded by Bloomberg Technoz.