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Energy saving metros

Discover how Thales is helping metro operators to tackle soaring power costs

Metro operators face huge challenges. Rising electricity costs are now top of the agenda, with power prices in many regions surging to all-time highs. Finding ways to cut energy consumption is a priority. In parallel with this, operators are under growing pressure to improve the environmental performance of their networks.


Green CBTC to the rescue

To address these challenges, Thales has a Green CBTC (communications-based train control) feature – a unique package of tools, technologies and services that work alongside our market-leading SelTrac™ CBTC signalling solution.

Green CBTC is purpose-built to cut the amount of power consumed by trains. And the savings it delivers are significant, with electricity demand reduced by 10-20%. What’s even more remarkable is that this substantial saving is achieved with an increase in journey time of just 3%. 

The beauty of the Green CBTC feature is that energy savings can be achieved with no disruption during deployment. And even better, Thales can deliver energy saving as-a-service, with no up-front capital cost.


Energy savings in action

Green CBTC works by fine-tuning the way that trains are driven and timetabled. So how is this achieved in practice?
Advanced coasting: a train is “coasting” when it is running with electricity so its traction motors shut off. The more a train coasts, the more power you save. A key part of Thales’ Green CBTC is calculating the best coasting strategy for every part of the line. We do this using our Speed Profile SIMulator (SPSIM) and Thales’ SelTrac™ CBTC Automatic Train Supervision (ATS).

Adaptive slow running: stopping or starting a train between stations is uncomfortable for passengers and wastes energy. Adaptive slow running keeps trains moving. This is done by reducing the speed of a train when a delay is expected. In parallel with this, dwell time is adjusted with the train held at the platform until it is able to embark on a non-stop run to the next station. Adaptive slow running is managed by Thales’ Automatic Train Supervision system.  

Regenerative braking: with regenerative braking, electricity generated by the traction motors of a slowing train is returned to the power system. This is “free” electricity that would otherwise be wasted. To make this work, a train that is braking needs to be matched with a train that is accelerating in the same power section. Thales’ ATS synchronises train movements to maximise regenerative braking, with minimal delays for passengers.

Peak limiting: in some cities, exceeding agreed peak power thresholds can trigger additional charges by energy suppliers. Demand spikes sometimes happen when several trains depart simultaneously within a given power section. To solve this problem, Thales’ ATS features a peak limiting function to restrict the number of trains departing at the same time within the same power section.

Power Distribution System (PDS) modelling: understanding how the power system manages traction energy is the key to successful energy saving. Thales uses PDS modelling to achieve this. This provides estimates of station-to-station energy consumption, as well as system-level energy consumption for multiple trains and multiple traction power sections. On top of this, PDS modelling provides an evaluation platform for Green CBTC algorithms.

Timetable optimisation: the process of timetable construction provides an opportunity to identify and capture energy savings. The timetable compiler within Thales’ ATS makes this easy, with visualisations and “what if” scenarios that show how much energy can be saved through schedule modifications.


Boosting passenger satisfaction

Green CBTC means lower energy bills for operators. There are significant benefits for passengers as well. These include:

Cooler stations, tunnels and trains: reduced power consumption by trains helps to keep air temperatures down – especially below ground.

Cleaner air:  research suggests that reduced reliance on friction braking – a major source of particulates – could help to improve air quality in stations and trains.

Smoother journeys: energy-saving driving profiles, with gentler acceleration and braking, contribute to smoother, quieter journeys for passengers.

Green CBTC is a win-win for operators and passengers – and a perfect example of our commitment to building a future we can all trust. 


Download our white paper to discover how Thales’ Green CBTC could transform your network:


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