European Train Control System
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The European Train Control System (ETCS) is a signalling, control and train protection system designed to replace the 14 incompatible safety systems currently used by European Railways, especially on high-speed lines.
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[edit] History
The specification was written in 1996 in response to EU Council Directive 96/48/EC of 23 July 1996 on the interoperability of the trans-European high-speed rail system. ETCS is developed as part of the European Rail Traffic Management System (ERTMS) initiative, and is being tested by six Railway companies since 1999. In Hungary, there is one ETCS Level 1-equipped line between Budapest and Hegyeshalom. ETCS Level 2 is used on the Rome - Naples line, opened in December 2005.
European railway networks grew as separate national networks that have little more in common than standard gauge. Notable differences include different voltages, signalling and control systems.
ETCS is divided up into different equipment and functional levels. The definition of the level depends on how the route is equipped and the way in which information is transmitted to the train. Basically, the movement authority (“permission to proceed”) and the corresponding route information are transmitted to the train and displayed for the driver in the cab ("cab signalling"). A vehicle fitted with complete ERTMS/ETCS equipment (EuroCab) and functionality can operate on any ETCS route without any technical restrictions.
[edit] Levels of ETCS
[edit] ETCS – Level 0
When an ETCS vehicle is used on a non-ETCS route this is known as Level 0. The trainborne equipment monitors the train for maximum speed of that type of train. The train driver observes the national trackside signals. Since national signals can have contradictory meanings, this level restricts drivers to their national borders. If the train has left a higher level ETCS, then that train might be limited in speed globally by the last balises encountered.
[edit] ETCS – Level 1
ETCS Level 1 is a cab signalling system that can be superimposed on the existing signalling system, i.e. leaving the fixed signal system (national signalling and track-release system) in place. “Eurobalise” radio beacons pick up signal aspects from the trackside signals via signal adapters and telegram coders (Lineside Electronics Unit (LEU)) and transmit them to the vehicle as a movement authority together with route data at fixed points. The on-board computer continuously monitors and calculates the maximum speed and the braking curve from this data. Because of the spot transmission of data, the train first has to travel over the Eurobalise beacon in order to obtain the next movement authority. With the installation of additional Eurobalises ("infill balises") or a EuroLoop between the distant signal and main signal, the new proceed aspect is transmitted continuously. The EuroLoop is an extension of the Eurobalise over a particular distance which basically allows data to be transmitted continuously to the vehicle over cables emitting electrical radiation. A radio version of the EuroLoop is also possible.
For example, in Denmark and Sweden, the meanings of single green and double green are contradictory, however since the ETCS Level 1 knows the difference, drivers can drive beyond the national borders safely.
[edit] Deployment
As of September 2007, several ETCS Level 1 installations are operational.
[edit] ETCS – Level 2
ETCS Level 2 is a digital radio-based signal and train protection system. Movement authority and other signal aspects are displayed in the cab for the driver. Apart from a few indicator panels it is therefore possible to dispense with trackside signalling. However, the track-release signalling and hence the train integrity supervision still remain in place at the trackside. All trains automatically report their exact position and direction of travel to the Radio Block Centre (RBC) at regular intervals. Train movements are monitored continually by the radio block centre. The movement authority is transmitted to the vehicle continuously via GSM-R together with speed information and route data. The Eurobalises are used at this level as passive positioning beacons or “electronic milestones”. Between two positioning beacons the train determines its position via sensors (axle transducers, accelerometer and radar). The positioning beacons are used in this case as reference points for correcting distance measurement errors. The on-board computer continuously monitors the transferred data and the maximum permissible speed.
[edit] Deployment
Several ETCS Level 2 in Switzerland and Italy are operational, while the new Netherlands freight lines has yet to be debugged.
[edit] ETCS – Level 3
In Level 3, ETCS goes beyond the pure train protection functionality with the implementation of full radio-based train spacing. Fixed track-release signaling devices (GFM) are no longer required. As in ETCS Level 2, trains find their position themselves by means of positioning beacons and via sensors (axle transducers, accelerometer and radar) and must also be capable of determining train integrity on-board to the very highest degree of reliability. By transmitting the positioning signal to the radio block centre it is always possible to determine which point on the route the train has safely cleared. The following train can already be granted another movement authority up to this point. The route is thus no longer cleared in fixed track sections. In this respect ETCS Level 3 departs from classic operation with fixed intervals: given sufficiently short positioning intervals, continuous line-clear authorisation is achieved and train headways come close to the principle of operation with absolute braking distance spacing (“moving block”). Level 3 is currently under development. Solutions for reliable train integrity supervision are highly complex and are hardly suitable for transfer to older models of freight rolling stock.
[edit] See also
