Obsolescence-Resilient Repair of Electrostar Fleet DCUs

Background

A large number of Alstom’s legacy Electrostar fleets have long relied on a specific model of Door Control Unit (DCU), which recently entered obsolescence as declared by the OEM. Alstom required a repair partner who could not only restore performance of the DCUs but do so with long-term sustainability and cost efficiency in mind.

Enter TP Matrix – specialists in electronic repair and overhaul within the rail sector. With deep experience in obsolescence management and complex systems testing, TP Matrix partnered with Alstom to develop a proactive, scalable repair solution for the entire fleet.

The Challenge: Repairing Obsolete DCUs at Scale

The task involved two primary challenges:

  • Restore failed DCUs to full operational condition, post in-service failure
  • Navigate and mitigate obsolescence risks, ensuring repairability over time

With over 6000 units in service and OEM replacements no longer an option, the economic implications of a full system replacement were significant – potentially running into millions of pounds across the fleet. TP Matrix’s repair-first strategy offered a compelling alternative.

Engineering Innovation: Automated Testing from Day One

From the outset, TP Matrix invested in developing a bespoke automatic test box to simulate full DCU functionality. This rig enabled:
  • End-to-end functional testing under load
  • Precise fault isolation
  • Verification of repairs with repeatable accuracy

This upfront engineering effort ensured every repaired unit could be confidently returned to service, meeting both safety and performance standards. It also streamlined turnaround times, reducing overall downtime for the fleet.

The Solution

TP Matrix receives each DCU following in-service failure. Together with Alstom, they defined a pre-agreed list of components known to:
  • Exhibit high failure rates
  • Be at risk of obsolescence

This list forms the core of the proactive repair process, allowing TP Matrix to replace vulnerable parts systematically, preventing recurring failures and ensuring consistency across repairs.

2024 Results at a Glance:

  • 383 DCUs repaired
  • 0 units unrepairable due to obsolescence

Results: Low Risk, High ROI

Repairing rather than replacing the Electrostar DCUs has already delivered substantial cost savings for Alstom. By avoiding the capital expense of a full fleet retrofit, Alstom has:

  • Extended the service life of its DCUs
  • Reduced waste and environmental impact
  • Preserved budget flexibility for other fleet priorities

Meanwhile, TP Matrix’s methodology ensures minimal disruption, maximum reliability, and a low long-term obsolescence risk.

Engineering Insight: Agile Component Management


The predefined replacement list has proven highly effective, addressing the majority of issues found across units. Only one component has since become obsolete. TP Matrix sourced a like-for-like alternative, secured full engineering change approval, and integrated it into the mandatory change list without affecting delivery schedules.

All other components replaced during repairs have shown no obsolescence issues to date. Furthermore, TP Matrix actively monitors emerging trends in component failures and adapts the repair scope in real time.

Alstom’s Engineering Manager for the GTR Project, Simon Lane said: “It has been a thoroughly enjoyable experience working directly with TP Matrix.  They have listened to us and our requirements, also noting that all and any changes must go through the correct process.  And as good to their word; TP Matrix have delivered at the right price, on time and on budget.”

Conclusion

Sustainable, Scalable Repairs

​This project demonstrates how a strategic, engineering-led repair programme can extend the life of critical fleet systems – without the cost or complexity of full replacement.

  • All 383 DCUs repaired in 2024
  • Zero unrepairable units
  • Obsolescence risks mitigated via agile sourcing and engineering approvals
  • Savings of hundreds of thousands vs. new unit replacement

Looking Ahead

Repairs are ongoing, and the collaborative framework between Alstom and TP Matrix continues to evolve.

With real-time data driving continuous improvement, this programme serves as a benchmark for how to manage ageing assets cost-effectively, balancing engineering integrity, supply resilience, and operational performance.

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