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Mobility and Transport


ERTMS system – technical questions

What is ERTMS? Sometimes we talk about the ERTMS and sometimes the ETCS. Are these to be considered as the same?

ERTMS stands for 'European Railway Traffic Management System'. It is a control, command, signalling and communication system. It is a software-based system for railway management and safety control. It was adopted by the European Union as a standard, allowing an interoperable rail frame in Europe. ERTMS is not the same as ETCS; ERTMS is composed of ETCS and GSM-R.

ETCS (European Train Control System)

is an automatic train protection system (ATP) that continuously ensures that the train does not exceed the safe speed and distance. In addition, it provides relevant information to support train drivers in their tasks.

GSM-R (Global System for Mobile Communications - Railways)

is a dedicated radio communication system for voice and data services supporting railway operations.

Do you need ERTMS equipment both on your corridor network and on your train in order to make it function?

ERTMS is composed of two subsystems: trackside and onboard, and in order to make it function, both the infrastructure and the train must be equipped.

How does the ERTMS work?

In the ERTMS system, the ERTMS system installed on the trackside and the ERTMS system installed on the vehicles exchange information. This information allows the ERTMS equipment installed onboard the vehicles to supervise the maximum speed allowed for operating continuously and to give the driver all the necessary information to operate with cab signalling. This includes the means to establish voice services.

What are the basic functions of ERTMS?

The basic functions of ETCS would include: management of the movement authorities that trackside sends to the trains, supervision of the most restrictive speed profile depending on fix/variable information. The GSM-R would include voice and data services. Voice services includes functionalities as group calls, emergency call and other railway specific applications.

What levels and baselines of ETCS are there? What is the difference between ETCS levels and baselines?

The baseline is a stable kernel in terms of system functionality, performance and other non-functional characteristics. Any system needs to evolve, and new functions and corrections might be needed.

“Baseline 2’’ is the first set of requirements, considered as interoperable, and to be adopted at European level.

“Baseline 3” is a controlled evolution of Baseline 2 that includes new additional functions and backward compatibility with Baseline 2.

The ETCS levels are defined depending on how the trackside is equipped and how the information is transmitted to the train.

Currently, there are three levels; all of them provide continuous supervision onboard:

  • Level 1 is a spot transmission but continuous supervision onboard. The information is transmitted to the train via Eurobalise (which is a transponder deployed on the trackside and connected to the signalling equipment) only when the train antenna is on the location of the balises.
  • Level 2 provides a continuous transmission of information between the train and the trackside via radio. In addition, the onboard equipment continuously supervises train movement. The train reports its position and direction of travel to the control centre automatically and receives movement authorities. In this level, the Eurobalise does not need to be connected to the infrastructure with cables. It allows the complete removal of lineside signals.
  • Level 3 is the most promising but least developed concept. The train supervises and reports its completeness, and there is no need for any kind of trackside signals or train detection system. Level 3 will be compatible with Level 2 and Level 1.

Both baselines include the definitions and requirements of the three levels, and therefore they are combinable with each other.


Level 1

Level 2

Level 3

Baseline 2




Baseline 3




What is backward or baseline compatibility?

Backward or baseline compatibility is independent from the level.


Loco equipped with baseline 2

Loco equipped with baseline 3

Trackside implementing baseline 2



(backward compatibility)

Trackside implementing baseline 3

Not compatible


Baseline 3 includes new functions that cannot be processed by a Baseline 2 train. Non-compatibility only appears if the trackside is equipped with Baseline 3 and the locomotive is equipped with Baseline 2. In this case, and due to these new functions, the locomotive is not able to run along this trackside.

The Baseline 3 train also includes Baseline 2, so they are also able to operate on a Baseline 2 trackside. The Commission therefore recommends that railway undertakings equip their locos with Baseline 3.


Support to the Commission and stakeholders

What is the role of the European Railway Agency vis-à-vis the ERTMS?

The European Railway Agency, in its role as a system authority for ERTMS, establishes a transparent process to manage, with the contribution of the sector's representatives, any system changes.

ERTMS is an “enabling” technology to allow exploitation of new business opportunities, operational improvements and efficiency streamlining.

On the other hand, the promotion of international traffic requires a seamless end-to-end service. Interoperability is essential to fulfil this objective.

What is the role of the ERTMS Deployment Management Team?

The main tasks of the Deployment Management Team (programme support action for the financing period 2014 – 2020) are 'the support of an efficient, synchronised, interoperable and timely implementation of the ERTMS deployment for each Core Network Corridor and to ensure the consistency on the network, both ERTMS trackside and onboard trains.' This can be divided into four areas, in which the DMT can make a substantial contribution:

  • Closely monitoring the implementation of the work plan, to avoid a patchy implementation of ERTMS in Europe.
  • Providing technical assistance to projects, aiming to remove the identified bottlenecks and avoid inconsistent deployment of ERTMS in Europe.
  • Building financial and economic methodological instruments and providing guidance to select the appropriate financing schemes according to the projects' specificities.
  • Providing an online one-stop-shop on ERTMS and other information, to share common knowledge.