European Train Control System (ETCS)

Train is approximating an Eurobalise

As standards and requirements change, are you fit for the future?

As ETCS pioneers, Siemens Mobility offers you mature, proven systems and products for individual applications as well as a scalable portfolio of lineside, on-board, and communication equipment. Ensuring that you are ready for what the future will bring.

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Product overview

Trainguard for ETCS

The Siemens Mobility solution for ETCS – the European standard.

The Trainguard system meets the most stringent safety requirements and complies with the Technical Specifications for Interoperability (TSI). Trainguard is based on a high-performance platform that provides reserves for future applications – offering you various functional configuration options in line with the various ETCS levels.



Trainguard features:

  • Interoperable
  • Futureproof
  • High operational reliability
  • Low lifecycle costs
  • High availability
  • Compact design

A solution for each ETCS level

Siemens Mobility offers a range of components and systems to meet requirements on both a European and global scale.

Trainguard 100 for ETCS Level 1 applications

On Level 1, movement authorities can be issued over several sections, enabling high-performance operation at speeds of up to 350 km/h.


Trainguard 100 transmits the information required on board trains via lineside balises. The variable track vacancy detection information is transmitted via the interlocking to signals and picked up by the LEU component, which translates and forwards this data to the trains via transparent balises. Fixed balises serve to transmit non-variable data, e.g. position information and track parameters. Operation without lineside signals is also possible if the LEU receives the signal aspect from the interlocking and forwards it to the transparent balise.


The cab display continuously indicates ahead to the driver the permitted speed and the line profile, e.g. speed restrictions and other operational and ETCS-specific data. Additional infills permit semi-continuous train control, meaning that the current signal aspect becomes effective even before the signal is passed. This is done either intermittently by means of Eurobalises or continuously using the Euroloop.


Migration can take place in parallel to existing legacy systems (Class B systems). In addition, Limited Supervision (LS) mode enables rapid migration in the event of restricted functionality. The ETCS Level 1 LS solution is a cost-optimized option for those customers launching ETCS.

The Trainguard LEU S21 forms the link between the existing fixed signals and the ETCS

Go to LEU S21 Page

Trainguard 200 for ETCS Level 2 applications

The key feature of ETCS Level 2 as opposed to Level 1 is the fact that the data is transmitted by radio to the train from a radio block center (RBC) using GSM-R.


Other radio systems, such as TETRA, may be used outside Europe. Therefore, only fixed balises are needed to determine the train’s position and to forward non-variable track data. Track vacancy detection and other information about point positions is transmitted from the associated interlocking to the RBC, which then generates the movement authority and sends it to the ETCS on-board unit. This considerably increases line throughput and driving “on electronic sight” through several section blocks enables short headways at maximum speed.


Your existing signals can still be used for mixed operation or as a fallback level, although they are not required for pure Level 2 operations.

Trainguard 300 for ETCS Level 3 applications

On ETCS Level 3, track vacancy detection components are no longer needed – resulting in cost benefits – as well as the possibility of virtual block or moving block operation. In Level 3, trains actively participate in route protection and need to reliably indicate their integrity and train length to the RBC. The RBC is thus capable of optimizing train traffic. A specific variant of this level is the so-called Hybrid Level 3 – which is a virtual block system overlaid on existing ETCS Level 2 wayside infrastructure.


With Trainguard 300 ETCS Level 3, Siemens Mobility can utilize its full system competence since on-board equipment, rolling stock and lineside solutions are all developed from a single source.

Trainguard on-board unit (OBU)

Comprising various subsystems, such as EVC and DMI, Trainguard OBU represents solid and highly reliable solutions already proven over millions of kilometers in commercial operation. This platform features compact housing, low power consumption, and a modular design supporting numerous applications and operating conditions – whether in the latest high-speed trains or for retrofitting maintenance trucks.


Trainguard OBU features:

  • High quality and service-oriented diagnostics
  • Low operational costs over lifecycle
  • Future-proof, modular and expandable
  • Optimized energy efficiency and deployment
  • Support for several radio standards e.g. GSM-R, TETRA
  • Conforms to Baseline 3 (compatible with Baseline 2) 


The automatic train operation system (ATO) controls the train's traction system and brakes so as to automate starting, accelerating, cruising, coasting, braking, and stopping.


The system is connected online with the trackside Traffic Management System (TMS), which in turn continuously transmits the latest timetable information. This allows the optimum speed profile to be calculated at any given time. All of the vehicle's acceleration and braking procedures are executed based on this speed profile as well as up-to-date track and timetable data. The result is a significant increase in energy efficiency and traffic flow. 


ATO is also the basis for higher Grades of Automation (GoA 3 and GoA 4) where the system is complemented by additional sensors and traffic management functionalities to enable driverless or unattended operation.


Key benefits:

  • Adaptable to every train type
  • Utilizes relevant track profile parameters
  • Optimal station-to-station runs
  • Remote and central coordination via the TMS
  • All solutions are customer-specific and can be implemented incrementally 


Technical compatibility

Technical compatibility of the Trainguard solutions for these different ETCS levels is your guarantee of interoperability beyond both system and national boundaries. The Trainguard system can be used for lines:


  • to be equipped with intermittent train control for operational reasons
  • where international and interoperable rail services are to operate
  • needing the safety level to be increased
  • on which older systems are to be gradually phased out
  • requiring minimum intervention in existing signaling systems


With our groundbreaking technologies, more than 100 years of experience and a global network of experts, Siemens Mobility can support you with our truly unique competence within the rail sector.

Technologies and systems for each ETCS level

EVC, DMI, JRU, trackside sensors
Trainborne integrity system
Level 0 / NTC
Level 1
Level 2
Level 3
'Trainguard' product brochure



Proven technology


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