KNKT Findings on Signalling Problem Prior to Bekasi Timur Train Collision

Jakarta, CNBC Indonesia - The National Transportation Safety Committee (KNKT) has disclosed an initial investigative report into the rail crash involving the Argo Bromo Anggrek train and the KRL Commuter Line service from Kampung Bandan to Cikarang at Bekasi Timur Station on 27 April 2026. The incident involved the Argo Bromo Anggrek train, number KA 4B, on the Gambir-Surabaya Pasar Turi route, and the KRL train number 5568A on the Kampung Bandan-Cikarang route.

This is the preliminary investigation result announced by KNKT at a hearing before DPR Commission V. The full investigation into the Argo Bromo Anggrek-KRL collision will be announced in three months’ time.

Chairman Soerjanto Tjahjono said in the preliminary report that there were three causes of the collision of the two trains. First, there was an anomaly in signalling between Bekasi Station and Bekasi Timur Station.

‘Based on the results of the railway service simulation (Train Stepping) conducted in the Bekasi Station Equipment Room and field simulations after the incident, with the scenario of the train route running directly from track 3 at Bekasi Station and the condition of track 104BT (the Bekasi Timur Station area) being occupied, the signal exiting J12 (Bekasi Station) can show the green aspect (symbol 5) or a safe aspect,’ Soerjanto said in his presentation at the hearing before Commission V of the DPR, on Thursday (21/5/2026).

‘The repeater signal or UB104 block repeater shows a horizontal illuminated white light (symbol 9C3) indicating a red block signal. Then the B104 block signal shows a red aspect (symbol 7). The railway service simulation conducted showed results consistent with the signalling aspects,’ he added.

This indicates that the signal at Bekasi Station could not detect the KA 5568A at Bekasi Timur, which means the signal exiting Bekasi Station shows a safe aspect or green light. Then the repeater signal shows an unsafe aspect or a flat-line lamp, and the block signal shows an unsafe aspect or red.

In fact, the exit signal from Bekasi Station should display a caution aspect or yellow light, if the preceding signal behind it still shows an unsafe indicator or red.

‘Signal at Bekasi which cannot detect the presence of 5568 (KRL) at Bekasi Timur has one condition—an unshift condition in that state,’ he said.