SMRT cites protocol breach in 17 Sept Circle Line disruption, while 18 Sept fire remains under investigation

Transport operator SMRT has provided an update on the two incidents that caused significant service disruptions on the Circle Line (CCL) on 17 and 18 September 2024.

The transport operator attributed the 17 September disruption to a breach in maintenance protocol, while the root cause of a fire that caused a disruption the following day remains under investigation.

Both incidents raised concerns about service reliability just ahead of a planned fare increase.

Incident on 17 September 2024

According to SMRT, the 17 September disruption began when a circuit breaker in the Traction Safety Shutdown System (TSSS) tripped, raising concerns that the fault could reoccur and affect train withdrawals later in the day.

In response, the maintenance team attempted to replace the Main Circuit Breaker (MCB37). However, SMRT explained that powering down the TSSS cubicle as a precaution caused a second circuit breaker (MCB33) to trip, leading to a power loss across the entire Circle Line.

SMRT acknowledged that the maintenance team failed to follow standard protocols requiring clearance from the head of Circle Line Operations before conducting corrective maintenance during service hours.

This breach contributed to the extended disruption, the company stated. SMRT emphasized that such corrective actions should have taken place during non-service hours to avoid impacting commuters.

The disruption affected services during the evening peak period, with trains stalled inside tunnels for up to 15 minutes.

According to SMRT, onboard batteries provided partial lighting and ventilation, although passengers reported discomfort due to the lack of air-conditioning.

SMRT resumed services gradually, with full operations restored by 7:40 pm. In a statement the following morning, SMRT explained that staff had worked overnight to diagnose the fault and ensure all systems were operational for the next day.

Incident on 18 September 2024

A day later, on 18 September, a fire broke out at Kim Chuan Depot, causing another power disruption. SMRT reported that the fire occurred around 8 pm in one of the power system cubicles within the depot, triggering a power trip that briefly halted train services across the Circle Line.

According to SMRT, the fire caused several trains to stall, and lighting within the affected trains was briefly impacted.

The Singapore Civil Defence Force (SCDF) was activated, although engineers at the depot were able to quickly extinguish the fire.

Power was restored by 8:10 pm, with full train services resuming at 8:15 pm.

SMRT issued a public apology on Facebook, thanking commuters for their patience and explaining that the swift response allowed services to be restored within 15 minutes.

SMRT stated that the fire triggered the Global Emergency Shutdown (GES) system, a built-in safety mechanism designed to shut down power across the line in emergencies.

While the exact cause of the fire remains under investigation, SMRT has isolated the affected cubicle from the power network and transferred operational control to a backup center.

Engineers from SMRT, the Land Transport Authority (LTA), and original equipment manufacturers (OEMs) worked through the night to investigate the incident and conduct safety checks to prevent further disruptions.

System Improvements and Investigations

While the root cause of the 18 September fire is still under investigation, SMRT is working closely with LTA to review the overall design of the TSSS and GES systems. The company is also conducting a comprehensive review of its fail-safe and fail-soft mechanisms to prevent similar incidents in the future.

In its public statement, SMRT highlighted that its priority is ensuring the safety and smooth operation of train services. The company has assured commuters that system resilience will be improved through planned upgrades, which include the introduction of new safety features and enhanced signalling.

Public Response and Concerns

The back-to-back disruptions have sparked frustration among commuters, with many taking to social media to voice their concerns. One netizen posted in the Facebook group "Complaint Singapore" about the 18 September disruption, and several other users expressed their dissatisfaction on SMRT’s official Facebook page. Some commuters pointed out that these disruptions occurred just before a planned fare increase, raising questions about the reliability of services.

Others criticized SMRT’s communication during the disruptions, with complaints about delayed or unclear announcements and equipment issues at certain stations. Several users urged the transport operator to improve communication and address technical shortcomings before implementing the fare hike.

In response to the public feedback, SMRT acknowledged the frustrations of commuters and committed to reviewing and improving its communication systems. The operator also reassured the public that system improvements are underway, including enhancements to the Circle Line’s signalling and PA systems. SMRT added that procurement for a replacement TSSS cubicle with enhanced fail-safe features is being expedited to bolster system reliability.