BISHAN depot in Singapore has been a mainstay of the city’s metro since it opened to serve the network’s first line in 1987. Located between Ang Mo Kio and Bishan stations on the North-South Line, the depot comprises a 12,000m² maintenance hall along with a stabling area with capacity for 59 trains.
The depot is operated by SMRT, and as well as fleet maintenance activities for trains used on the North-South and East-West lines, it is one of two sites where the carries out 198 train overhauls every four years.
Yet SMRT is under pressure to speed up this work. Socio-economic changes in Singapore are requiring the metro network to transport more people more efficiently. The government is responding by approving capacity expansion projects on existing lines as well as committing to a major new line construction programme, which will extend the network to 360km when completed in 2030.
Increasing the intensity of train operations is in turn placing fleet maintenance activities under more strain, including at Bishan. The situation is compounded by the demographic profile of staff working at the site. Already a quarter of technicians are above the age of 50, and in 10 years’ time this will increase to over 40%. SMRT is also experiencing difficulties in recruiting their replacements, observing that the working environment at the near 40-year-old depot is unattractive to the “tech-first” generation. “We cannot continue to perform maintenance in the current manual and labour-intensive way,” says Dex Hong, director, rolling stock engineering, at SMRT.
SMRT therefore considered how it could optimise its fleet maintenance strategy. Ruling out increasing its staff headcount, and unable to build more depots due to the scarcity of suitable sites and high costs of building in Singapore, it focused on introducing smart processes and streamlined working at the depot. The result is Depot 4.0, which embraces automation and AI-enabled digital control systems and has completely redesigned the end-to-end workflow at Bishan.
When embarking on the project in 2023, SMRT commissioned its engineering and technology subsidiary Strides Technologies to totally rethink SMRT’s strategy for train maintenance and overhauls. Aligning its work with Singapore Land Transport Authority’s (LTA) Rail Digitalisation Roadmap, Strides partnered with CRRC Qingdao Sifang to harness CRRC’s experience of automating train manufacturing. The Chinese supplier subsequently developed, designed and supplied the relevant automation equipment and associated digital systems for the project. SMRT contributed to this process by providing its expertise in fleet maintenance and management to Strides’ engineering and technical experts who worked to translate SMRT’s operational needs into the necessary systems and processes.
During the project, the partners adopted a kaizen philosophy of continuous improvement involving all employees, from C-suite management to the shop floor, commencing work in September 2024. The upgraded depot was subsequently commissioned in November 2025 and is delivering as anticipated, with the overhaul of a single train at Bishan now taking just one week compared with two previously and requiring 30% fewer people than before.
Reinventing the workflow
The partners began the project by examining existing workflows with a view to reconfiguring these processes to better match the capabilities of Bishan’s shrinking and ageing workforce. In practice, this involved altering the depot layout along with identifying labour-intensive and mundane activities which could be automated or improved through the introduction of smart equipment.
“Infrastructure modifications were constrained by the existing depot building footprint, which has been around for four decades,” says Yishen Yap, Depot 4.0 project manager at Strides Technologies. “We kept civil works to a minimum and reused existing equipment, tracks and turntables where possible.”
The resulting reconfiguration streamlines workflows and processes to enable the seamless transfer of key components undergoing overhaul to different workstations around the depot, speeding up work by reducing technician waiting times and eliminating unnecessary movements. The highlight is a set of new automated rail-guided vehicles for moving bogies, which eliminates the need for heavy lifting while improving access for technicians overhauling the bogie by moving autonomously from one workstation to the next.
Purpose-built disassembly and assembly machines are further automating other labour-intensive processes while digital inspection equipment is improving component assessment and measurement, helping to eliminate errors and boosting confidence in the results. Digital tools such as smart torque wrenches are enabling high-precision maintenance and real-time data logging for critical components, enhancing quality control. Ergonomic jigs are similarly helping to improve health and safety in the workplace, while driverless forklift trucks are improving logistics within the depot while again reducing the need for human intervention.
Digital management
To combine all these processes and improve the management of people and tasks within the depot, Strides, working with CRRC, developed an AI-enabled Maintenance Information Management System (Mims).
Mims has transformed the management of activities at the depot from spreadsheet-based planning to an AI-enabled digital system. Indeed, Hong says Mims helps to shorten planning, coordination and communication cycles by consolidating and sharing all relevant information in real time. Conflicts and shortages are flagged early to allow for timely resolution, while the duration of specific tasks as well as equipment utilisation and staff allocation are all closely monitored and tracked, offering the scope for continuous process improvement.
“We kept civil works to a minimum and resued existing equipment, tracks and turntables where possible.”
Yishen Yap, Depot 4.0 project manager at Strides Technologies.
“In the past, the information required for maintenance planning resided in multiple systems and among multiple stakeholders, such as our Maintenance Management System, HR database, and logistics inventory spreadsheets,” Hong says. “Maintenance supervisors had to communicate with the various stakeholders through conventional channels to gather the required information. They then had to make sense of what they were told in order to make the correct decision.
“Mims consolidates work orders, manpower availability, materials availability, equipment readiness, and task progress automatically by drawing them directly from the respective data sources and systems into a single digital platform for maintenance planning and execution.”
Maintenance staff contribute to the collection of this information by using digital task reporting in their work. This has enabled substantial improvements in accountability and the efficiency of these processes by enabling supervisors to directly observe the live status of work and any exceptions to workplans rather than seeking updates through calls or messages.
In addition, Depot 4.0 incorporates condition-monitoring systems to assess the health and usage of depot overhaul equipment. “With this, Mims is able to provide real-time oversight of the workshop in order to monitor progress, and flag problems before they impact maintenance performance,” Hong continues. “Mims enables our supervisors to coordinate and communicate actions across their teams to keep the plans on track.”
Digital challenge
While extensive staff training has been undertaken at Bishan depot, Hong says change management was the biggest challenge facing the successful rollout of the Depot 4.0 concept. “Our technicians and supervisors have been performing overhauls in an analogue environment for decades,” he says. “Convincing and training them to adopt and optimise digital technology and robotics was an important and deliberate task.”
Ultimately, this process of adapting to the new environment was made easier by involving managers, technicians and other maintenance staff early in the process. “We did this inclusively and consulted them throughout the entire transformation: from problem identification, design, and solution finding to final transformation,” Yap says. “They visited sub-suppliers overseas, tested the new equipment, and participated in evaluation and factory acceptance tests to improve design as well as strengthen buy-in.”
Another significant challenge was to safely and efficiently overhaul the facility while continuing day-to-day fleet maintenance. Yap says this required the careful staging of works and close coordination between different parties in order to sustain daily depot output.
Success at Bishan is encouraging SMRT to undertake automation and digitalisation projects at other depots in Singapore, with Mandai on the Thomson-East Coast Line earmarked for the next project. However, Yap notes that the level of automation and digitalisation will be customised to meet the individual needs of each depot. Fleet maintenance is also set to become increasingly predictive rather than reactive. He reveals that SMRT is working with CRRC to introduce on-train health monitoring systems to improve diagnostics as well as lay the groundwork for a future predictive maintenance regime.
“We are working on automating and digitalising component-level maintenance and overhauls to deepen our domain knowledge in rolling stock,” Yap says. “The data from these solutions will be analysed and used to drive continuous improvement by tightening integration between planning, execution, and quality control. This will culminate in a holistic health and usage monitoring programme to improve reliability and enhance journeys in Singapore.”
With the Depot 4.0 project now completed and delivering results to expectations, SMRT believes it has developed an effective solution to managing fleet maintenance demands arising from more intensive metro operations. Depot 4.0 should also leave SMRT well-placed to manage the upcoming human resources challenges posed by an ageing workforce and a tough environment for recruitment, a common conundrum for rail and transit operators worldwide.
About SMRT
SMRT is one of two metro operators in Singapore. It is responsible for operating and maintaining the North-South (NSL), East-West (EWL), Circle and Thomson-East Coast (TEL) lines as well as the Bukit Panjang LRT. SBS Transit operates the North East Line (NEL) and the Downtown Line (DTL) as well as the Sengkang and Punggol LRT lines. In addition to Bishan, SMRT operates fleet maintenance depots at Ulu Pandan (EWL and NSL), Tuas (EWL), Kim Chuan (Circle), Mandai (TEL) and Bukit Panjang (LRT). The East Coast Integrated Depot, a new three-storey facility for three metro lines and bus fleet maintenance, opened at the end of 2025, initially servicing EWL trains. Trains deployed on TEL and DTL will begin operating out of the depot in the second half of this year.
