SINGAPORE – The expected time of arrival system used to communicate bus timings on bus stop displays and apps will be restored to 85 per cent by the morning of Jan 28.

The entire system will be fully recovered only early next week, about one week after the

expected recovery date of Jan 26

which was announced earlier.

Sharing this information in a press release on Jan 27, the Land Transport Authority (LTA) said it has finished manually updating the firmware for 3,000 affected buses which were identified in the week of Jan 19.

But it has since identified another 1,000 buses that require similar manual firmware updates to fully restore the bus arrival system.

LTA added that it will complete these updates over the course of the week, since this process can take place only after service hours.

Bus services will continue to operate as scheduled, it said.

Passengers were unable to check when their buses will arrive from 8pm on Jan 21 to the start of passenger service on Jan 23, as part of the Land Transport Authority (LTA)’s move to reset the system to tackle the problem of inaccurate bus timings and longer wait times being displayed to commuters.

According to checks by The Straits Times at around 4pm on Jan 27, LTA’s app MyTransport.SG displayed relatively normal bus timings – with intervals of around seven to 15 minutes between each bus – for many services.

But the timings for the third arriving bus were not available for some services, while others had longer wait times – of over 30 minutes – being shown.

LTA had said in the evening of Jan 22 that it would take another four days, or till Jan 26, to completely fix the technical issue as the authority needed to work with the contractor to reconfigure the system and clear the cache on affected buses.

Having first detected this issue on Jan 10, LTA said the wrong information was caused by an intermittent transmission issue with the on-board systems of some buses.

The authority then discovered that the issue was caused by a memory cache build-up in some on-board bus systems.

Typically, a cache stores data that is frequently used to retrieve information more quickly. But as the cache stores more and more data, it could result in systems behaving more sluggishly – and potentially glitching or crashing.

The memory cache build-up disrupted data transmissions between buses and the central servers that compute the estimated arrival times, affecting about half of the entire bus fleet in Singapore.

Reconfiguring the system and clearing the cache on affected buses involves physically servicing the devices on these vehicles, which was estimated to take about four days – starting from Jan 23 – to resolve.

Even after switching on the bus arrival system on Jan 23 for testing and stabilisation, LTA said that bus arrival timings would not be fully available or accurate.

The authority had previously said that over 60 per cent of these timings would be available on the system then.

“We thank commuters for their patience as we continue working on resolving the issue and apologise for the inconvenience caused,” said the authority.

Esther Loi is a journalist at The Straits Times, where she covers transport issues.