Extent of Inconvenience and Gaps Discovered from Recent Disruptions in Bus Expected Time of Arrival System

Written Reply to Parliamentary Questions

Ms He Ting Ru asked the Acting Minister for Transpo

a.    whether the bus Expected Time of Arrival (ETA) system disruption on 18 April 2026 revealed gaps in system redundancy;

b.    what was the extent of this disruption, including services, stops and commuters affected;

c.    what fallback mechanisms exist to ensure ETA system continuity for such disruptions; and

d.    how LTA is addressing similar disruptions and known reliability limitations.

Ms Mariam Jaafar asked the Acting Minister for Transport in light of recent disruptions affecting the accuracy of bus arrival timings including incidents linked to technical faults and external infrastructure damage

a.    whether the Ministry has reviewed the resilience of the Estimated Time of Arrival (ETA) system; and

b.    what steps are being taken to strengthen system reliability and reduce the impact of such incidents on commuters.

Reply by Acting Minister for Transport Jeffrey Siow: 

1.     The Estimated Time of Arrival (ETA) system relies on physical fibre-optic connections to relay updates on bus locations to a central server, which then computes predictions of bus arrival times.

2.      For data security reasons, bus location data is transmitted through dedicated pairs of fibre-optic cables that are privately leased from a commercial vendor. By design, if data cannot be sent through one cable, it will be re-routed to the other cable, so that the connection continues to function. This provides a backup against physical damage.

3.      On 18 April 2026, Asia Piling Co damaged several fibre-optic cables when carrying out works. One of the damaged cables was part of a physical connection transmitting to the ETA server. As designed, data was diverted from the damaged cable to the intact cable in that connection pair. However, not all data was successfully sent to the server when the incident first occurred. This resulted in a degradation of the ETA system performance, with only 70% of the expected number of ETA predictions throughout the rest of the day.

4.      The ETA system was restored to full functionality after the fibre-optic cable was repaired. Our investigation revealed no other hardware or software malfunctions in the ETA system, and no relation to the outage that took place earlier this year.

5.      The Land Transport Authority is still investigating why the remaining intact cable did not provide full redundancy for the damaged cable as required of the vendor.

6.      We are currently upgrading the ETA system. The new system, which will be deployed by the end of 2027 will be hosted on a cloud platform. This will improve the resilience of the ETA system against physical damage to its data connections.