The scenic Mont-Blanc Express railway stretches approximately 54 kilometers between Saint-Gervais-les-Bains in France and Martigny in Switzerland. Opened in 1906, it was designed to improve connectivity, boost local travel and facilitate tourism across the mountainous Franco-Swiss border and is widely regarded as one of the best rail journeys in the Alps.
However, while the steep gradients along the picturesque Alpine terrain contribute to the route's appeal, they also pose significant challenges for traction power. Railway networks operating on steep, sloping terrains often face severe fluctuations in traction power, impacting overall efficiency and stability over long distances. Without a systematic approach to ensure a reliable power supply, these disturbances can impede the performance of electrical systems, potentially resulting in voltage drops, while engendering power losses and escalated utility costs.
As part of an extensive upgrade of its Vernayaz substation, which serves one of the steepest points of the route where gradients can reach up to 20 percent, Transports de Martigny et Régions (TMR), the Swiss arm of the Mont-Blanc Express line, sought to develop a regenerative power solution to improve resilience and lower its environmental impact.
Enter ABB’s advanced Enviline Energy Recuperation System (ERS), which enables rail networks to return surplus braking energy back to the AC network, with the scope for recoverable excess braking energy being as high as 30 per cent of the total yearly energy consumption of the rail transportation system. The Enviline ERS and an ABB Thyristor Controlled Rectifier (TCR) were installed at the Vernayaz substation. The TCR has advanced capabilities in controlling DC line voltage and preventing interruptions caused by voltage drops, thereby enhancing the stability and reliability of the power supply. This setup ensures that the railway line operates more reliably and efficiently by providing a steady and resilient power source.
The collaboration between ABB and TMR resulted in a project that was successfully inaugurated on 15 May 2024. The thorough simulation and testing of the solution before installation ensured that the upgrade was completed with minimal disruption to the busy railway line. This upgrade enables power, previously lost when trains descend a 20 per cent ramp, to be recovered and reused, enhancing operational efficiency and reducing energy costs, along with associated carbon emissions.
Thomas Meier, management member and co-head of infrastructure at Transports de Martigny et Régions, stated: “With ABB’s regenerative power solution, we remain on track to reduce our environmental footprint and enhance the quality and reliability of our service. The upgrade at this key substation will ensure our trains reliably and efficiently transport the thousands of passengers they carry each week, while allowing us to reduce our daily operating costs and move one step closer to a more sustainable future.”
The benefits for the Mont-Blanc Express have been substantial. The enhanced stability and reliability of the power supply have improved operational efficiency, established approximate annual energy savings of 552 MWh (the equivalent electricity consumption of 200 households), and increased the punctuality of train services.
