LTA probes backup cable failure after April outage disrupted Singapore bus timing system

SINGAPORE: The Land Transport Authority (LTA) is investigating why a backup fibre-optic cable failed to function after construction works damaged underground telecommunications infrastructure on 18 April, disrupting Singapore’s bus arrival timing system and broadband services.

Acting Transport Minister Jeffrey Siow said in a written parliamentary reply on 6 May that the incident affected the transmission of bus location data after several fibre-optic cables were damaged during works carried out by construction firm Asia Piling.

The damaged cables caused the bus arrival timing system to operate at only 70 per cent capacity for the remainder of the day, resulting in inaccurate waiting times displayed at bus stops and on mobile applications.

“Not all the bus location data was sent to a central server on 18 April,” Siow said in response to a parliamentary question from Workers’ Party MP He Ting Ru.

The outage also caused extensive broadband disruptions in parts of Singapore, affecting customers across major internet service providers.

How the disruption occurred

Siow said bus location data is transmitted through dedicated pairs of fibre-optic cables designed to reroute information automatically if the primary cable fails.

However, the backup arrangement did not function as intended after the construction works damaged multiple cables, including one responsible for transmitting bus information.

Full functionality was restored only after the damaged cable was repaired later that day.

Investigations found there were no hardware or software malfunctions linked to the incident. Authorities also determined the outage was unrelated to a separate disruption reported in January.

The incident occurred during contiguous bored piling works linked to the North-South Corridor project.

The construction method involves drilling large vertical holes into the ground before filling them with concrete to create retaining walls for excavation.

Broadband outage affected four towns

About 5,000 broadband subscribers in Ang Mo Kio, Bishan, Sengkang and Punggol experienced service disruptions after 25 telecommunications cables were damaged underground.

In a separate parliamentary reply, Siow said investigations into the incident remain ongoing and agencies may take legal action if Asia Piling is found culpable.

Telecommunications operators may also seek damages from the contractor over the service disruptions.

“The construction works were being done as part of the North-South Corridor project,” Siow said, adding that contractors are required to comply with utility agency requirements when working near underground services.

Under Singapore law, contractors convicted of damaging telecommunications cables can face fines of up to S$1 million, imprisonment of up to five years, or both.

System upgrade planned by 2027

Siow said the bus arrival timing system is currently undergoing an upgrade aimed at improving resilience against similar incidents.

The upgraded system is expected to be deployed by the end of 2027.

According to Siow, the new version will be hosted on cloud infrastructure to reduce the risk of physical disruptions affecting service continuity.

The move is intended to improve the system’s ability to withstand damage to physical data connections and maintain operations during outages.

The current incident has raised concerns about the vulnerability of critical public transport and telecommunications systems to accidental infrastructure damage during construction works.

Questions in Parliament focused on whether existing redundancy measures were sufficient and what safeguards could be strengthened.

Telecommunications resilience under scrutiny

Separately, Minister for Digital Development and Information Josephine Teo addressed broader telecommunications resilience measures in a written reply on 5 May to Workers’ Party MP Fadli Fawzi.

Teo said the Infocomm Media Development Authority requires infrastructure provider NetLink Trust to ensure its network remains resilient during outages.

She said the provider has already implemented redundancy and path diversity measures across cable routes.

However, Teo noted that route duplication is more difficult in areas closer to homes because of underground space limitations.

“Route duplication is not possible nearer to homes where there are underground space constraints,” she said.

Teo added that telecommunications operators are required under the Telecom Service Resiliency Code to restore disrupted services as quickly as possible when outages occur.