ETCS, simply summarized (English version)

The inglorious rail news this July 2013 gave railway signaling on the front of the stage, especially with the tragedy of Santiago de Compostela. The main problem seems to be that the transition between ETCS 2 and the national level, said "STM". A brief overview to put together the various pieces of the jigsaw, with an article which is deliberately lightweight, in order to make easy the learning and understanding.
Incompatibles national systems
Since the beginning of the century, almost all railroads of Europe were nationalized. And who says national railway say national technology, at this time when Europe was synonymous with war, destruction and most importantly, everyone in their own borders. Since the 50s, the progress of electrical helped establish two essential elements for signaling and traffic control:
1) the lateral signaling on which the drivers must unconditional obey and,
2) the train detection system, which is never mentioned, which is essential for the detection of trains and traffic management through a centralized cabin.

The both go together : occupying a track circuit of 700 to 2000 m means the presence of a train, which influences the appearance of the signals behind the train to avoid the risk of catching by another train. The development of security has changed how to drive a train: some yellow or flashing aspects or other signals aspects require an acknowledgment from the driver, who must push on an ad-hoc button to confirm that has read the right signal with is good appearance. If he does not, there is in principle an emergency stop, but there exist cases with more complex figure where it's different. We are of course not entering into details.

All this to say that this signaling technology has developed over the decades on the basis of strictly national criteria. From one country to another, protection systems are not identical and do not provide the same quality of safety. And that is a problem for the European rail market ...

At the meantime…
The lateral signaling has its limits, particularly in terms of line’s capacity: 6, 8,10 trains per hour, some lines no longer offered any possibility to increasing the number of train without a complete overhaul, and very expensive, of the signaling area. Came the idea of ​​transposing to the “commuters trains”  what is done with TGV, AVE and german’s ICE :give orders in the driving cab, and do not obey to lateral signals. Extensive program here brought together several networks and manufacturers to edit - finally - the accepted obligatory for all common standards. It was sufficient to…

There are previously 3 levels of ETCS. Its implementation on a classic line is ex officio superposition with existing signalization, which should not be removed. Why? Because during the next fifteen / twenty years ahead or more, older trains will continue to run without being equipped with ETCS on-board equipment, because they will go in early future to  scrap metal yard.   We have today a mixture of non-equipped trains and equipped trains.

Cardinal principle: transmission of information on board.
This theme appeals to the general public: it seems simple, with a "simple mobile”.  But in the case of a SIL 4 safety rail factor, transmission of information on board is much more complex than the “publics toys interfaces ",  we can see to these pages.

In level 1: information is transmitted by balises in the tracks. This already complete technology allows short messages and do not support the speed curve. In addition, the train receive the information sporadically, when it passes on each balises. The driver always observed lateral signals, which demonstrates the importance to do not disassemble any part of the existing signalization.

The balise in the track for transmission of information to the locomotive (photo Siemens Mobility)

In Level 2information is transmitted via GSM-R radio and reverse to level 1, the information is transmitted permanently and unfocused. We can therefore give orders to train any second. One of the two balises is necessary to odometry: it confirms the position of the train in combination with track circuits as mentioned above. The driver no longer observed any lateral signal and refers only to its single control panel on board called "DMI" (Driving Machine Interface). The level of security is dramatically increased : all speed curves are subject to supervision, which is not the case of level 1

In level 3 : it is today a piece of science fiction. This level diverges dramatically from the other two levels by the disappearance of track circuits and balises, and by creation of a "complex bubble" between each train. The calculation is made by three satellites and look like of a GPS system, except that the accuracy tolerance must be less than 0.5 m ...!

What does this mean in practice ?
In Europe, it is now requested that any new line, "HSL" or not, must be designed to integrate ETCS 2. But for safety reasons, some networks continue to install lateral signalisation required for ETCS 1, usually on "no-HSL" lines. The most importantly project, is the gradual introduction of ETCS up to the classic network to enhance security. This led in 2012 a mini-debate in Germany where it was told that the national system already ensured adequate security and did not see the added value to be gained with implementation of ETCS.

The superposition of three systems on the same line also has a other important advantage: in case of failure of level 2, we need to activate the so-called "fall back" mode, ie down to "Level 1" or for some cases, to "national system".

In Switzerland, the Mattstetten-Rothrist line was the first to be equipped with ETCS 2. The Lötschberg base tunnel that connects Frutigen to Rarogne, near Brig, is also equipped with ETCS 2. Thalys and ICE running since late 2009 with ETCS level 2 ​​on Belgian LGV L3 (Liège-Aachen) and Belgian-Dutch L4 (Antwerp-Rotterdam). In Netherlands, the famous Dutch Fyra, with TRAXX locomotive, running with ETCS 2 on Amsterdam-Rotterdam-Breda route by taking the high-speed lines (HSL-Zuid). Freight line “Betuwelijn” (Rotterdam-Germany - 158km) is currently fully equipped with ETCS level 2. In Spain, HSL Madrid-Lerida and Barcelona-Figueras-Perpignan are equipped with ETCS 2.

Thalys on HSL-Zuid between Netherlands and Belgium : ETCS level 2 (photo Rob Spots via flickr CC)

The future
To avoid fragmentation of implementation and to etablish an international cohesion, Europe has established a network of "ERTMS corridors" (ETCS is a part of the ERTMS), outside the future TGV lines. This concern mainly freight corridors such Rotterdam-Genoa or Antwerp-Basel. The construction of only two next TGV lines in France, SEA and Bordeaux-Toulouse, will be fully in ETCS2, as well as the English HS2, on the route London-Birmingham today in discussion . Three countries, Denmark, the Netherlands and Belgium, choose to opt for the full implementation of ETCS on the entirety of their networks, a focus which should take 12 to 15 years according to current schedules.

The usual release today remains V2.3.0d but the new Baseline 3 version should be out by the agency that is responsible: European Railway Agency (ERA), located in Valenciennes.

To consult :
ETCS in the details and description of interfaces;
A map of worldwideimplementation, ERTMS-ETCS is sold at the global level;
Web pages with worlwide's statistics;
Documents version "Baseline 3" agency ERA;
ERTMS in Ten Questions