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Modernising Croydon's Tracks: Power Demand Solutions for Modern Tram Networks

London Trams - Case Study


Following our previous works on several substation networks in Croydon, London Trams approached East Solutions to replace outdated battery and charger units found throughout their electrical network.

Before East Solutions started working on site, London Trams had been using 85 SBM65 NiCd cells installed back in the late 1990s for their battery chargers. To enhance Power System resilience by mitigating the risk and impact of faults, the obsolete equipment would need to be replaced with serviceable alternatives, with spares being freed up for the remaining outdated equipment, via the installation of novel battery and charger systems.

 Project Facts    


East Solutions in-house Technical Department completed a full set of CAD drawings and provided a comprehensive list of manufacturer-recommended components to the client ahead of the project’s launch. The completed specification was designed to replace existing battery chargers that had been in service since the 1990s and were nearing the end of their lifespan. East Solutions innovative design concept incorporated smart technologies to enable remote monitoring of the battery condition, ultimately streamlining the maintenance regime. The equipment update was carried out in three phases.

During Phase One, initial preparation work for the replacement was conducted, which included taking out a possession and isolation of the relevant section, testing the tripping system, marking up the cabling and core numbers, and performing any necessary preparation work, such as the installation of cables and containment. These tasks ensured a safe and efficient replacement of the charger unit and associated batteries and compatibility with the existing network. Phase Two involved installation of the temporary charger unit, testing on the temporary unit, and switching of the supplies from the existing charger to the temporary unit. This phase enabled the safe disposal of redundant equipment and installation of the newly specified replacement equipment, including required modifications to the connections to the LV AC supply, control supply distribution system, and interfaces with the SCADA system.

Finally, the last phase of the project involved taking out a possession and isolation of the relevant section, removing the temporary charger unit, testing the live functionality of the new charger unit, and switching the supplies from the temporary unit to the new charger. A commissioning team was deployed to test, verify the correct operation, and assure the quality and safety of the equipment prior to energisation. Upon project completion, East Solutions provided the client with a full set of updated H&S files and site-specific training for the appointed person on the new system.

The project demanded close oversight and coordination of all parties involved to effectively track key milestones, timelines, and deliverables. To ensure seamless communication and collaboration between the manufacturer, design team, and client, a dedicated project manager and coordinator was assigned to the project.


The team faced several challenges while upgrading the site within the existing substation. The space constraints posed significant difficulties in installing and accommodating the new components required for the upgrade. Moreover, working within a confined space required strict implementation of additional safety measures to ensure the work was carried out securely.

To meet London Trams’ project deadline, works were required to be carried out during the day while trams were in operation, with final changeover and testing scheduled for overnight. This rigorous timetable meant that works could only commence after 11 pm and had to be completed no later than 5 am the following day.

 The Results 

Replacing obsolete equipment offers several benefits. Enhancements made to the power supply system have increased its reliability, availability, and maintainability, ensuring a more resilient system with improved operational efficiency and reduced downtime. Moreover, replacing the obsolete battery and charger units with new units that have lower maintenance costs significantly reduces the lifecycle cost of the power supply system. This will provide London Trams with improved budget predictability and financial stability.

Additionally, replacing the battery and charger units will extend the mean residual life of the assets, leading to longer periods of operation before requiring replacement or significant maintenance. Overall, these improvements to the power supply system will reduce service impacting failures and improve service reliability.


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