Monday 21st Oct, 2019

Latest-generation CBTC driving urban rail modernisation

Graphic: Thales

Rail Express speaks with Thales’ Arnaud Besse about the company’s seventh-generation SelTrac CBTC system.


Over three decades since commercialisation, Thales’ SelTrac Communications Based Train Control (CBTC) system has been installed on more than 100 metro lines, in over 40 major cities around the world, and moves more than three billion passengers every year.

Thales launched the future-focused seventh generation of the SelTrac train control system, SelTrac G7, at Innotrans 2018, and will demonstrate the system again at AusRAIL PLUS 2019 in Sydney later this year.

Arnaud Besse, Marketing and Communications Director for Urban Rail Signalling at Thales, tells Rail Express the new generation of SelTrac is aimed at helping passenger operators achieve 100 per cent availability of service.

“Every operator wants to reach 100 per cent availability of service, and so do we,” Besse says.

Changes in SelTrac G7

With the share of global population living in cities expected to rise from 50 to 70 per cent by 2050, governments around the world must not only build new rail lines, but must maximise the capacity of existing infrastructure.

Thales says it has developed its SelTrac system with this in mind: SelTrac G7 is designed to be as flexible as possible, to help different operators, on new and existing lines, using varied rollingstock.

“SelTrac is both valid for greenfield and brownfield projects,” Besse explains, “and we are rollingstock provider agnostic. We have installed our system in trains from 14 different rollingstock manufacturers, which is pretty much every major rollingstock manufacturer on Earth.”

Besse says after safety, the top priority in the development of SelTrac G7 has been working with customers to assess their needs.

The result is a forward compatible system designed to ensure long and extendable design life, without the need for disruptive, system-wide re-signalling every time a new line is added or a new fleet enters service.

Thales says SelTrac G7 features a set of advanced functions designed to better help public transport operators manage network growth, extensions and fleet expansions, and prepare for the future of control operations.

Thales has improved the user interface for the centralised command-and-control system, which uses web technologies to allow users to work on their own workstations. The equipment installed on trains is also 20 per cent more compact for SelTrac G7, than for previous generations.

The seventh-generation system is also designed to operate with any kind of telecommunication system, including new-generation LTE, which is notably favoured in China over WiFi for CBTC communications.

Besse says one key innovation in SelTrac G7 is a bidirectional line management capability. This means if there is an issue at any given time, anywhere on the network, the operator can reconfigure the entire network to reduce or eliminate downtime.

“When you have an incident on your line, SelTrac G7 can very quickly and safely put in place any provisional services that require trains to do something they’re not usually supposed to do,” Besse explains.

“This means when a potentially disruptive incident occurs, the overall impact on the passenger and the operator is minimised.”

This added flexibility ties in with SelTrac’s decision support system, or DSS. “When an alarm occurs on the line, the DSS will propose to the operator a few scenarios,” Bess explains. “If there is a train broken down at a station, for example, the system could propose one option to run a provisional service, another for trains to skip the station, or turn around, and present the information needed for the operator to decide.”

Another customer-driven improvement made to SelTrac G7 relates to the first ‘C’ in CBTC – communication. When a train loses communication, SelTrac G7 allows it to continue until it reaches the limit of its movement authority. This means temporary, brief communications outages don’t impact operations.

“Our customers told us that losing communication on one train should not necessarily mean they don’t have room to manoeuvre, i.e. that the train cannot at least proceed with a few monitors. After all, in CBTC you are providing a limit of movement authority – basically how far the train can go given its position.”

In the case where a train does not re-establish communication before reaching the edge of its movement boundary, it will stop. But, as in most cases, if it has re-established its connection to the system, it will be able to continue.

“It’s all about minimising the cost of operations,” Besse explains. “Any disruption on the network costs the operator money, and costs satisfaction for the passenger. Nobody likes to be stuck on the network for additional time.”

With major research and development always going on in sectors like mission critical defence, security, and avionics, Thales has also applied its developments in cybersecurity to the new generation of SelTrac.

“The technology behind encryption analytics and hardware that we are supplying to banks, for example, is the same that supports SelTrac G7,” Besse says. “We have the best cybersecurity experts looking at our system, trying to break into it, and advising how it can be made even more secure. This relationship also means we have kept cybersecurity as one of the design constraints throughout development – so SelTrac G7 is what we call ‘cybersecure by design’.”

Always moving block

Besse credits the level of innovation Thales is able to achieve with SelTrac to the history of the system itself.

First developed by Standard Elektrik Lorenz (hence SEL in the name) in the 1970s, the technology now known as SelTrac began as the first fully automatic moving-block signalling system. It has never been a fixed block system, and is not based on fixed block technology. Besse notes this means Thales is not attempting to move innovation over from a fixed block mindset, into moving block; instead that innovation is always being made with moving block as the status quo.

Part of this alternative approach means SelTrac has been designed to not require a secondary train detection system, which can cost millions of dollars to install and maintain. Typically, such systems are installed as fixed “backup” systems, using things like axle counters to detect when a train enters a section of the network.

“This would be a fixed block system, added to a moving block solution,” Besse reasons. “Because our competitors are coming from a fixed block background and moving to a moving block, this secondary train detection is embedded into their system. But we started from the other end, so we don’t need it.”

Besse notes SelTrac has been used in Vancouver for more than 30 years without secondary train detection.

“We can equip a secondary train detection system if our customer wants one, but SelTrac does not need one by definition. And from our perspective, this secondary train detection infrastructure becomes another thing that can eventually impact the availability of the network.”

Flushing line conversion

Thales recently helped MTA New York City Transit convert one of its busiest subway lines, the Flushing line, to full CBTC, and launched Automatic Train Operation (ATO) capabilities on the line in May.

The Flushing line, which serve 400,000 daily passengers, went into revenue service using SelTrac CBTC in December 2018. A Certificate of Substantial Completion was finalised for the project in March 2019. Two months later, in May 2019, Thales ATO capabilities were enabled.

Thales says the project was the first irreversible re-signalling cutover project in North America. Modernising 17 kilometres of track connecting 22 stations with a fleet of 46 trains, the result of the project is a more efficient operation.

On-time performance since revenue service began has increased by more than 16 percentage points to 91 per cent. For riders, the average amount of time they now spend onboard a train beyond their scheduled travel time has been slashed by over a minute, to just 39 seconds.

The ATO also means train operators can put more focus on platform procedures and emergency breaking, while the train runs automatically.

“We are committed to supporting the future of New York City with its Fast Forward plan and contribute to increased public transit capacity for New Yorkers,” Thales Urban Rail Signalling Managing Director Dominique Gaiardo said in July.

“By re-signalling one of the busiest lines in New York, Thales has once again proven its outstanding capabilities in urban rail modernisation.”

Thales to bring SelTrac G7 to Australian Market

Thales is actively engaging with local industry to bring it’s SelTrac G7 solution to the Australian Market – starting in Sydney and then expanding to other neighbouring geographic regions.

“Thales is excited to bring this world class CBTC solution to the Australian market in order to help our local customers achieve their project objectives – it is already in operation in a number of major cities around the world – reducing congestion in our customer’s cities and improving the safety of their networks, reducing travel times for their commuters and providing major economic and social benefits to their countries,” General Manager of the Ground Transportation Systems business for Thales Australia Elias Barakat said.

Contact: thalesgroup.com

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