ETCS is the European Train Control System promoted by the European Commission for use throughout Europe, and specified for compliance with the High Speed and Conventional Interoperability Directives.

The system aims to remedy the lack of standardization in the area of signalling and train control systems which constitutes one of the major obstacles to the development of international rail traffic. Unifying the multiple signalling systems in use will bring increased competitiveness, better inter-working of freight and passenger rail services, stimulate the European rail equipment market, reduce costs and improve the overall quality of rail transport.

ETCS is in fact an automatic train Protection system, based on cab signalling and spot and/or continuous track to train data transmission. It ensures trains operate safely at all times in providing safe movement authority directly to the driver through the cab display and in continuously monitoring the driver’s actions.

Activity Presentation

UIC as a worldwide organization representing railways administrations does not only focus on European activities even if UIC actively contributes to the ETCS development and evolution through the European railway organizations such as CER, EIM and ERTMS User’s Group recognized by the European Community to support the ERA for satisfying its mandate.

In 2007, two main projects have been proposed and widely supported by our members.
These projects are entitled “ETCS – Core Activities” and “ERTMS Regional”.

ETCS – Core Activities is composed of the following work packages:

  • Support to members for ETCS implementations including Corridors on Eastern Europe such as corridors X, V and IV
  • Support to European railway organizations recognized by the European Railway Agency
  • ETCS braking curves algorithm, conversion model and safety margins determination, in close cooperation with EEIG
  • Influence of ETCS on line capacity
  • Dissemination of information on ETCS to members

ERTMS Regional concept is the outcome of a close co-operation between UIC and the Swedish Infrastructure Manager Banverket since 1998.
This concept aims at defining a full track side system for regional lines based on and fully compatible with ERTMS system.

UIC has, in corporation with the European rail administrations, elaborated the Functional Requirements Specifications for such track side ERTMS application.
On this basis, the Swedish infrastructure manager launched in 2004 a call for offer for a pilot line between Repbäcken and Malung (134 km) and signed a contract with Bombardier Transportation in 2005 for installation of ERTMS Regional

Today, UIC activities within ERTMS Regional project are organized as follows:

  • Support to Banverket for SRS and FFFIS specifications
  • Dissemination of Banverket project to members
  • Organization of European workshops on UIC & Banverket specifications
  • Update UIC specifications with needs from European railway administrations participating to the workshops

More details on each activity can be found on the dedicated pages.

Standards and Specifications

The current legal references for European Train Control System are hereafter-presented.

  • The Conventional Rail Technical Specifications for Interoperability relating to the Control-Command and Signalling (CR CCS TSI) had been adopted by the Commission on 28 March 2006 and notified the same day to all Member States. It had entered into force on 28 September 2006 and had been published in the Official Journal of the Communities on 16 October 2006. This document is available at the following URL: Conventional Rail TSI on CCS (2006/679/EC).
  • The High Speed Technical Specifications for Interoperability relating to the Control-Command and Signalling (HS CCS TSI) had been adopted in 2002 and its annex A (list of mandatory specifications) had been modified in 2004. The SRS 2.2.2 were already included in the HS CCS TSI Annex A in 2002 and were kept in the 2004 modification.
  • The revised HS CCS TSI adopted by a commission decision of 7 November 2006, has been notified to all Member States and has entered into force the same day. It has been published in the Official Journal of the Communities on the 7 December 2006 and is available at the following URL:
    High Speed TSI on CCS (2006/860/EC).
  • On the 6 March 2007, the Annex A of both the HS CCS TSI and CR CCS TSI was adopted by the Commission and notified to the Member States in the decision 2007/153/EC, entering into force the same day. The updated ERTMS documents are the subset 108 (index 15) whose version 1.1.0 contains a list of corrections applicable to the previous SRS and accompanying documents, as well as the corresponding updated SRS 2.3.0 (index 4) and the new definition of ETCS marker board (index 38).

The annex A to these TSI enumerates the mandatory and the informative specifications for ERTMS, and the mandatory standards; all documents are available on the European Railway Agency website.

One has to consider that specifications above-listed are under evolution and consequently are updated regularly. All relevant documentation including latest issues of specifications can be found on the European Railway Agency website.

ETCS Core Activity

In addition to the dissemination of project results and specific support to our members which constitute our basic assignment, UIC has actively participated since many years in the definition of the ETCS braking curves, considered by all stakeholders as vital for ETCS development.

Expectations from ETCS as an advanced signalling solution are in some circumstances the increase of line capacity and service quality and hence the improvement of the cost-benefit equation for Railway Undertakings and Infrastructure Managers.

UIC has leaded several studies on this critical topic related to the influence of ETCS system on infrastructure capacity.

Technical details of these analyses are presented on the dedicated pages.

Support to Railway Administrations

One of the main assignments of UIC consists in giving technical assistance to its members mainly composed of railway administrations and organizations. ETCS team is full involved in this assistance activity on different topics and in cooperation with several European organizations.

ETCS team supports the railway organizations recognized by the European Railway Agency in taking part in the monthly meetings leaded by the Community of European Railways and the ERTMS Users Group to determine the positions of railway administrations on the current ETCS related issues submitted by the ERA.

ETCS and braking systems experts from UIC belonging to the working group B126.15 leaded and funded by UIC have been actively involved since many years in the definition of the brake curve calculation for ETCS under the leadership of ERTMS Users Group. The tight and efficient collaboration between experts from UIC and ERTMS Users Group has permitted to significantly improve the original braking curve algorithm and models as defined in the specification document 97E881. The fruits of this collaboration are detailed in the dedicated page.

Within the framework of members assistance related activity, ETCS team provides technical support to railway administrations involved in the development of the European corridors X, V and IV. In concrete terms, several ETCS experts from UIC have taken part in the definition of the national implementation plan at technical level for the different railway administrations of the corridors above-mentioned.

ETCS Braking Curves

During their development, the railways in Europe have adopted their own technical standards and operating rules according to national requirements. As a result, the European railways use different train control systems (INDUSI, KVB, LZB, TVM, ATB etc.) and have different warning distances. This situation constitutes a serious obstacle for interoperable high speed and conventional trains.
To overcome this obstacle, the standard European train control system ETCS was developed.

The specifications for the braking deceleration of trains operated with ETCS must ensure the interoperability as defined in Directives 96/48/EC and 2001/16/EC with respect to interoperability of the trans-European high-speed and conventional rail system.

Presently, for almost all trains in Europe operating at up to 200 km/h, the only information available for the quantitative description of braking performance is the braked-weight percentage. The braked weight is usually determined empirically on the basis of stopping distances obtained by testing and according to UIC Leaflet 544-1. It is an effective way of expressing the ability of any train to stop over a certain distance when travelling at a given initial speed.

ETCS as most of the automatic speed supervision systems requires knowledge of the braking performance of a train in the form of its instantaneous deceleration as a function of speed.
As a consequence, it was necessary to develop a new method for describing the braking performance of all train categories running in an ETCS environment.
The expert group B126.15 A from UIC has looked into this issue and has defined a conversion model which has been approved by EEIG ERTMS Users Group and hence integrated into the reference document EEIG 97E881 “Description of the brake curve calculation”.

The model converts the ?-value into a speed dependent deceleration-function expressed as a step-function.
The model is applicable for all types of trains with a wide range of braking systems and different deceleration characteristics by using only the ?-value, the type of the train (passenger/goods), the train length and the G/P brake position as input parameters. It allows the calculation of the distance S that is necessary to reduce the speed from the current value v to the target speed.

Further to the definition of the ? conversion model, the expert group B126.15 A from UIC still in tight cooperation with EEIG ERTMS Users Group has proposed a new algorithm for ETCS braking curves. This algorithm which will be tested in the course of the year 2008 in the simulation centre from DB offers a solution more practical and realistic for railway operations.
The mathematical description of this algorithm is contained within the document EEIG 97E881.

ETCS system features speed control amongst its functionalities, allowing the emergency brake to be applied when there is a risk of the train passing the danger point.
The system thus calculates a curve in the Speed-Distance plane designated EBI, which determines when the emergency brake is to be applied, to guarantee protection of the danger point.
The stopping distance taken into account must be very safe (guaranteed) such that the risk of passing the danger point is extremely small. The calculation of stopping distance and the decelerations taken into account therein must therefore incorporate “safety margins”.
In order to ensure the interoperability of trains on the Railways’ networks and avoid problems during their passage from one country to another, it is necessary, on principle, to unify the approach to safety margins.

The main task of the Working Group UIC B126.15C aims at proposing a unified method to calculate these safety margins. The calculated safety margins must not be excessively high to avoid jeopardising the capacity and throughput of lines.

The first analysis of the current knowledge on safety margins has not given an applicable solution to the problem. In fact, every European Railway Network has its own rules for the safety margin determination on classical signalled lines (refer to document B126 DT 393 on and those that have a recently installed ERTMS applications utilise different principles (refer to B126 DT 407 on

The working group B126.15C has investigated methods adapted both to justify a scientific approach of calculated safety margins and to obtain an acceptable method across the entire European Railway Networks. All details of the proposed methodology for the safety margin calculation of the emergency brake intervention curve can be found in the technical documents B126 DT 414 (on

Influence of ETCS on Infrastructure Capacity

Expectations from ETCS as an advanced signalling solution are in some circumstances the increase of line capacity and service quality and hence the improvement of the cost-benefit equation for Railway Undertakings and Infrastructure Managers.

The issue of the influence of ETCS on the infrastructure capacity has been considered by UIC as highly important. For this reason, UIC has started going deeper into this topic since many years and has commissioned the RWTH Aachen University (Institute of Transport Science) to perform different studies on line capacity.

Based on the harmonised blocking-time model as prescribed by the UIC Code 406 for describing capacity consumption, the first step of this set of studies funded by UIC was to assess the influence of train control systems with infill functionality, including ETCS level 1, on line capacity. Comparative analysis between ETCS level 1 and existing national signalling systems such as INDUSI, PZB or LZB have been carried out.

The framework of this first study includes neither complex railway cases like nodes or stations nor the safety aspect of infill functionality.

The full report of this first capacity study is available for UIC members.

The next step of this set of studies has been to focus on the influence of ETCS in its different configuration on the line capacity in order to document the best practices achievable with ETCS system.

Starting from the definition of some reference cases for infrastructure, transport schedule and punctuality levels, the influence of ETCS and of its different configurations has been studied and quantified. In order to be independent from national influencing factors, generic infrastructure characteristics have been used for the assessment of capacity consumption. Typical conventional line, high speed line and regional line have been considered and for each kind of line a specific operational program and punctuality requirements have been defined.

The capacity study includes the different configuration of ETCS including Level 1 with LS, L1 with infill, Level 2 with usual and optimised block sections and also Level 3. Comparative analyses between the different configurations of the system are presented and some recommendations are suggested.

The full report of this second capacity study is available to download for free on

A third report was written on the specific issue of capacity in nodes (big stations).
This report is available to download for free on


Jean-Michel Evanghelou

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Thursday 27 August 2015