SMRT’s first upgraded C151B train returns to service on Jun 21 with new smart diagnostic systems

Commuters travelling on the North-South and East-West lines (NSEWL) can look forward to taking the upgraded C151B train – fitted with smarter and improved systems to boost rail reliability and commuter comfort – as it returns to passenger service on Jun 21, 2026.

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The 5th-gen C151B train on the North-South, East-West lines (NSEWL), in its original livery. (Image: SGTrains File)

The 5th-gen C151B trains first entered passenger service in 2017, and are scheduled to receive mid-life upgrades by 2032, typically when they reach around 15 years old.

However, rail operator SMRT collaborated with the train’s manufacturer CRRC Qingdao Sifang in 2024, supported by the Land Transport Authority (LTA), to retrofit one C151B train with the latest reliability-centred features, as part of a proof of concept (POC).

This upgraded C151B train, Trainset 649/650, dubbed the POC train or Prognostic Health Monitoring (PHM) train, would be used to test new features in real-world operations before considering them for future train upgrades.

Unique to this C151B train is a new vibrant and bold red and white livery that features Singapore’s skyline and technology-inspired motifs, with SMRT saying it reflects their mission to “leverage automation and AI to provide a safe, reliable, and comfortable journey”.

Various new features and systems of the upgraded C151B train

LTA said the upgraded C151B train has been levelled up with various AI-powered systems and automations, with SMRT mentioning that about 180 new sensors were installed in hard-to-access areas, such as the train’s undercarriage, as earlier reported by AsiaOne.

These are in line with the recommendations by the Rail Reliability Taskforce that was formed in September 2025, to develop and implement immediate solutions to improve rail reliability and joint responses to train service disruptions.

One of the key features is the Structural Health Monitoring (SHM) with the embedding of a suite of strain and vibration sensors across the carbody and bogie to monitor the structural health data, including early fatigue monitoring, by processing through advanced algorithms.

In addition, a condition monitoring system (CdM) monitors train performance in real time using a built-in algorithm that examines performance data and triggers alerts on anomalies.

“Enhanced Cybersecurity: We embed cybersecurity into every component – hardware and software – to establish a secure data pipeline.” (Image: Screengrab from Singapore Transportation 2581/YouTube)

A bogie monitoring system (BMS) keeps track of bearing health through temperature and vibration sensors within the bogie, triggering early warnings when anomalies occur.

Moreover, the upgraded air conditioning and ventilation (ACV) system enhances commuter comfort and reduces environmental impact through the use of high-efficiency components and low-GWP (global warming potential) cooling refrigerant.

As earlier mentioned, SMRT and CRRC Qingdao Sifang explored future-proofing the propulsion and auxiliary power systems through replacing obsolete parts and increasing power capacity.

All of these upgraded features would be reflected in the upgraded Train Integrated Management System (TIMS) that provides detailed and accurate information on the health status of critical onboard train systems.

Similar upgrades could be implemented across the fleet of 4th-gen C151A, 5th-gen C151B, and 6th-gen C151C trains

The upgraded C151B train has returned to passenger service along the NSEWL at Ang Mo Kio station on Jun 21, collecting trial data and real-world information for validation.

LTA said that should the trial be successful upon validation, it will work with SMRT to implement these solutions on 91 other trains built by CRRC Qingdao Sifang.

These 91 trains would consist of 35 units of the 4th-gen C151A – operating since 2011, 44 other units of the 5th-gen C151B – operating since 2017, and 12 units of the 6th-gen C151C – operating since 2018.