Inaccurate bus arrival timings caused by defective software after server failure: Jeffrey Siow
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There have been issues in displaying accurate bus arrival times on bus stop displays and bus apps since Jan 10, with the system still shy of a full recovery on Feb 7, when the LTA said it was restored to over 90 per cent.
ST PHOTO: LIM YAOHUI
- Defective software and a server failure caused bus arrival timing issues, affecting about 4,000 buses, with no cyber-security concerns reported.
- The software has been fixed to prevent recurrence, and timing predictions are over 90% restored.
- The system aims for 95% accuracy within three minutes, met historically. A bus fleet management system upgrade will improve estimates further.
AI generated
SINGAPORE – Early investigations found that the root cause of the recent bus arrival timing issues was a software defect on the buses, triggered by a server failure in January, Acting Transport Minister Jeffrey Siow said.
This led to a build-up of data in the internal memory storage of data transmitters on buses, which eventually prevented many transmitters from functioning properly, he said in a written parliamentary response on Feb 12.
The defect has been fixed, and the system’s performance is stabilising, he said, adding that “the same error should not recur”.
“There are no cybersecurity concerns,” Mr Siow said.
He was answering questions from Sengkang GRC MP He Ting Ru on whether the bus arrival timing issues raised cybersecurity and resilience concerns, and how many bus services and commuters were affected.
There have been issues in displaying accurate bus arrival times on bus stop displays and bus apps since Jan 10, with the system still shy of a full recovery on Feb 7, when the Land Transport Authority (LTA) said it was restored to more than 90 per cent.
Mr Siow said about 4,000 buses were affected by intermittent data transmission and missing bus arrival timing predictions.
But he noted that, as buses are deployed across services at different times, the authorities do not have an estimate of the impact on commuters. Bus operations, however, were not impacted.
He also noted that the system’s performance had met the prescribed performance target over the past three years.
To Aljunied GRC MP Kenneth Tiong’s questions on the accuracy standards and historical accuracy rate of the bus arrival timing system, Mr Siow said the system is expected to predict actual bus arrival times within a three-minute range at least 95 per cent of the time.
But he added that there would be some “inherent variation” in bus arrival times due to differences in how long buses spend at preceding bus stops and varying traffic speeds caused by congestion, accidents or roadworks.
In response to Ms He’s question on what checks are conducted to verify the accuracy of the system, Mr Siow said predictions from the system are cross-checked against the actual arrival times of buses logged through a separate bus fleet management system to identify spikes in inaccurate or missing predictions.
He noted that an upgrade to the bus fleet management system has also been in progress since 2024, integrating and improving bus arrival timing estimates.
“The Land Transport Authority (LTA) is closely monitoring the reliability and accuracy of the bus arrival timing system and has taken remedial actions to prevent a recurrence,” Mr Siow said.
LTA had earlier announced an expected recovery date of Jan 26, before pushing this to early in the week of Feb 2.
Mr Siow said on Feb 7 that the recovery “has taken a bit of time” because it involves a manual refresh of the permanent software and, in some cases, replacing the transmitters on affected buses.
