Sncf's tgv safety System

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SNCF's TGV Safety System

By Gerard Boqueho,
Deputy Director for Operating and Safety Systems


A dedicated system for trains worked at high speeds.

To run trains at very high speeds it is necessary to have special purpose infrastructure and rolling stock combined with specific operating conditions. To provide a secure environment for high-speed lines and minimise the risks of collision with people, animals and road vehicles, 2 metre-high fencing is installed along the line and level crossings are not allowed (the lines are built on "separate grade").

SNCF's high-speed lines (LGVs) for high-speed trains (TGVs) running at up to 300 km/h are reserved exclusively for passengers. Some parcels trains with specific consists and with a specific power-to-weight ratio and braking system may also be operated on the HSLs (LGVs) at speeds of up to 200 km/h.

The HSLs are double tracks workable in both directions, allowing trains to operate at full speed, irrespective of the direction, on either track. Crossovers between the Down and Up lines (numbered tracks 1 and 2) are made at reduced speed (170 km/h on the pointwork). These crossovers are spaced about 25 km apart and provide a means of coping with any eventual traffic incidents. Ground-to-train radio is used for communications between drivers and traffic controllers who set up routes remotely.

Each TGV high-speed train has a permanent, fixed consist and an axleload not exceeding 17 tonnes, with a power car at each end of the rake of articulated trailers. The trailers are coupled together via a bellows ring resting on a bogie. Most TGVs have 8 trailers, but there are 10 in the TGV Atlantique (the TGV-A) and 18 in the Eurostar. Their capacity can be doubled by coupling two or more trainsets (except for Eurostars) via the automatic coupler in the nose of all the power cars. The bogie wheelbase is optimised at 3 metres to guarantee better stability at high speed. The trainsets are at least dual voltage, sometimes triple or quadruple voltage in the case of those running on neighbouring foreign networks.

The driver receives the speed limit indications on his cab-signal display. These are fed in as coded frequencies or digital messages carried in the current flowing in the rail strings. The driver's role is not limited to watching automatic controls operate; human beings remain “in the driving seat” and are therefore still able to react, if the situation suddenly deteriorates. On the other hand, driving aids make the driver's task easier and the continuous speed control system trips emergency braking if the train's speed becomes incompatible with safety. It takes 3 kilometres to stop a TGV running at full speed. Accordingly, when it must be slowed, decrementing speed limit indications are transmitted to the driver in the form of a restrictive sequence.

Besides complying with the speed limits, the driver must also observe the train timetable at the various staging points along the route. He must also conserve energy thanks to his line-of-route knowledge by alternating between motoring and coasting to make the best of the line profile, since the line can have down-gradients of up to 35 millimetres per metre.

System components contributing to the high standard of safety on HSLs

  1. HSL architecture

The HSLs are divided into block sections the bounds of which are signalled by reflector marker plates called "repères" mounted on wayside posts.

Nf marker

Line protecting marker

F marker

Block section marker

Every 20 to 25 km are signalboxes controlling :

  • either a simple crossing to another line in the event of two-way working,

  • or, in 50% of cases, a double crossover to a passing loop,

  • or, less frequently, a station serving as a passing loop in the line layout (the station then has a passing loop on both sides to be able to receive two trains simultaneously).

  1. Headway

The principle of the track-to-train signal transmission system (TVM) consists of modulating the current flowing in the track circuit by superimposing upon it a frequency characteristic of the data intended for a vehicle running over or arriving at the particular track circuit. The information is received in the vehicle by means of sensors (receivers) mounted at the front of the first axle. This transmission system, supplemented by the onboard display, constitutes the Cab Signal, which obviates the need for traditional lineside signals.

The TVM 300 (used on the Southeast and Atlantic HSLs) is a system that uses 1 out of the 18 frequencies possible. This capacity is only sufficient to meet the needs of the in-cab display.

The newer TVM 430 has 28 superimposable frequencies. Seven of them are used for encoding the transmission control so as to provide a very effective speed control system aboard the TGVs. This upgrade, combined with better scaling of the speed steps that optimise the allocation of braking energy to be dissipated over the block sections crossed during the stopping or deceleration sequence, makes it possible to divide the line up into basic block sections 1500 m long on level track, as compared with 2000 m with TVM 300. It thus allows greater line throughput by reducing the minimum headway between two trains to 3 minutes (instead of 4 minutes with the TVM 300).

Figure 1 : Principles of the TVM 430 track circuit-based track-to-train transmission

The signalling information is transmitted continuously from the track to the vehicles via the cab signal display. It allows the continual display of a speed that is not to be exceeded by the driver in the case of "execute new speed" information or to be observed as soon as possible in the case of advanced warning of a speed restriction.

To make every one of the possible speed indications compulsory, a continual speed monitoring and control trips automatic braking of the train if the speed exceeds the threshold (step) authorised by the displayed indication. Such automatic braking can be interrupted and overridden by the driver as soon as the speed falls below the speed control threshold.

The following items of equipment along the track supplement these basic features :

  • danger signal markers with “no override possible” (Nf) or “override possible” (F) and shunting markers. These markers only operate if they are approached while a "zero" or "all red" indication (signal aspect) is displayed in the cab (the latter two indications also command the driver to stop before the first marker he encounters down the line),

  • electric traction-related signalling,

  • ground-to-train radio signalling,

  • special signalling in respect of temporary speed restrictions (160 km/h) for track work.

  1. Cab-signal displays

The cab signal display shows only a single indication at a time. Six types of information can be displayed in the cab : speed limit data, outer distant (advanced warning of) speed limitation, distant speed limitation, execute speed limit, stop ahead, and proceed "at sight" (with caution) or make emergency stop.

Figure 2 : Exemples d’informations présentées sur le visualisateur de la cabine

Authority to run at 300 km/h

Authority to run at 270 km/h up to the end of the block section; in next section the driver may receive a warning indication

Distant signals: the first instructs the driver not to exceed 230 km/h on entering the next block section.

Execute speed : orders the driver immediately not to exceed the speed shown.

Distant signals : order the driver not to exceed the speeds shown on entering the next section (flashing display tells the driver that the next indication may be more restrictive)

Zero display orders driver to stop before the first marker ahead.

"All red" display orders the driver to proceed with caution and stop before the first marker ahead.

In the normal situation, a restrictive indication can only appear at the entry to a block section. However, the flashing of the first restrictive indication in a distant stopping sequence may occur inside a block section ; this possibility is used, for example, to stop a train when a build up of heat in an axlebox is detected by a hotbox detector.

The "line clear" (end restriction) indications are given as soon as possible. In some traction vehicles used for work trains the transmission of a speed indication greater than or equal to the vehicle's own top speed causes the letters "VL" ("line clear") to be displayed in white characters against a green background.

  1. Monitoring and control of speed and of danger signal override

Based on the data sent by the TVM equipment on the ground, the onboard TVM computer determines the following parameters: the initial control speed (VCI), the final control speed (VCF) and the braking coefficient (GU) applied, in stages, according to the speed control curve. These parameters serve to develop a speed control curve that :

  • will not interfere with a driver who is executing a normal deceleration,

  • yet will stop the train before the protected point or enforce a speed limit at the speed limit execute point, if the driver fails to comply with the commands displayed.

To prevent the speed control system interfering with the driver, the point to be protected is always located in advance (downstream of) the point at which the signalling orders the driver to stop or slow down. The minimum distance between the point where the speed restriction or stop is to be executed by the driver and the actual protected point where the automatic speed control intervenes is called the overlap. Hence, stop orders to protect a given point on the line are issued by "closing" a marker located at a distance greater than or equal to the necessary overlap distance in relation to the point under consideration.

The speed control associated with the TVM cab signalling monitors the driver's behaviour all through a stopping sequence, but is no longer active when the speed falls below 35 km/h. This arrangement is sufficient to ensure compliance with a "danger signal with override possible" (F) marker but an additional arrangement has to be provided to signal that it is absolutely forbidden to override an Nf (no override) marker at the start of a route.

Override control of a stop signal is activated when a the indication “zero” or “red” is displayed to the driver of a train located upstream from the given marker. This requires an intermittent information transmitter to be placed downstream from the Nf marker to trip emergency braking in any vehicle passing the marker at danger.

  1. Stopping sequences

The conditions that trip a stopping sequence, e.g. block section occupied, route not set or section of track protected for track work, and those that trip a speed reduction sequence (turnout set for diverging track, actuation of a manual lineside switch, application of interval protection, etc.) are usually external to the moving vehicle and are communicated to the TVM in real time.

Figure 3 : Example of stopping sequence for a TGV running at 300 km/h

  1. HSL protection systems

  1. Protection of staff and works

In view of the high speeds worked on HSLs railway staff must be forbidden to enter the right-of-way unless the appropriate protective measures have been taken beforehand.

Traditional works protection schemes are insufficient and so it was necessary to install special protection systems called "protection switches" that act on the signalling and bring about a speed reduction or halt in traffic.

These are manual switches installed on the wayside, on both sides of the line. They are used for two purposes :

  • as a supplementary protection measure for maintenance-of-way (MoW) staff in addition to the protection implemented by the signaller,

  • as protection of an area in the event of an obstruction, available to railway staff called to the site (MoW personnel or driver).

The block section(s) affected by the lineside switch is (are) represented on a "Protection" plate that shows where the person operating the switch is located in relation to the tracks. When one of these switches is operated it causes a "red" indication to be displayed in the cab throughout the "protected" section or sections in both running directions. At the control centre, an indicator lets the signaller know that a protection by manual lineside switch has been set up.

  1. Train protection

Protection over the distance between signalboxes :

The signaller has the option of commanding "running at sight" over an entire "interval" between signalboxes, track by track, by manually-keyed computer communications from the control centre. Such an overall "interval" protection order produces an all-red indication in the cab throughout the interval, in both running directions, incremented by the necessary overlap. Interval protection makes it possible, in stations for example, to react very quickly to problems arising on the tracks or platforms.

Speed reductions ordered by the Train Controller:

From his computer keyboard in the signalbox, the Train Controller can order overall speed restrictions to 170 or 230 km/h in conversation mode from Central Traffic Control. The advantage of this facility is to be able to reduce the speed of all trains in an extensive geographical area both quickly and easily. For example, when speeds must be reduced to 230 km/h because of bad weather, this type of control avoids the need to issue speed reduction orders to each individual driver entering the area concerned.

Speed reductions controlled by manual switches:

Speed limitations to 80 or 170 km/h can be commanded using switches located in the outer equipment rooms of the switchgear and equipment rooms of the remote-controlled signalboxes. These switches are positioned geographically on a panel representing a simplified diagram of all the track circuits controlled by the TVM ground equipment of the signalbox concerned. They are used mainly for enforcing temporary speed restrictions (TSRs) but may also be used whenever train speeds must be limited.

  1. Automatic monitoring systems

  1. Fallen vehicle detection (DCV)

All road bridges crossing HSLs have a system to protect against road vehicles falling onto the track. In addition, a system to detect falling road vehicles (DCV) is installed for road bridges spanning the HSL when the configuration of the road-rail intersection and the quantity of road traffic at the location raises the probability that a road vehicle might fall onto the line. This system consists of two interlinked metal nets on either side of the bridge. If a vehicle falls, both nets will break simultaneously, giving the alarm (this is the "detection" function).

Associated visual indicators are provided which signal the fault or the detection to the signaller at central control. The detection of a fallen vehicle immediately triggers the associated track protection, which consists of emitting the "all red" data item on both tracks, in both running directions. The danger signal is given over the whole of the structure plus the necessary overlap distance on each side of it. There is an alarm cancelling pushbutton at the detector site, which can be used after consultation with the signalman to remove the protection once the vehicle has been cleared from the track or in the case of a spurious detection. The DCV is then inhibited and the speed on the line section is automatically reduced to 170 km/h until the MoW department has reinstated the detection equipment.

  1. Flooded track formation detection (DPI)

Pumping stations are installed on sites where the relief characteristics do not allow to be sure that the natural run-off would be sufficient in case of downpours. The equipment of these stations is therefore supplemented with a device able to detect a flooded track formation (DPI), the aim of which is to slow down or to stop the trains automatically through an action on the signalling device.

At the station level, two detection thresholds allow to require :

  • either a speed limit at 80 km/h, after a detection of water at the sub-layer’s level of the track formation; execute speed (080) is to be executed on each track in both running directions, with overlap and upholding ahead on the whole of the risk zone, such as defined ;

  • or a stop in the runnings, after a detection of water at the at the foot of rail’s level; the information “red” is to be executed on each track in both running directions, with overlap and on the whole of the risk zone, such as defined.

A global controlling of the display at each switch tower indicates a detection requiring a stop at anyone pumping station situated in the action zone of this switch tower. So as not to disturb the traffic in case of unjustified detection, two pushbuttons, allowing to cancel the protection, are installed on each side of the track formation, close to the lowest location.

  1. Seismic detection (DSI)

The watching on seismic hazards (Mediterranean HSP) is provided by a central post of seismic detection installed in the signal box controlling the HSL; it is composed of two processing and storage units. The signal box is furthermore equipped with a manual device of cancellation and stopping of the alarm. Two detection thresholds are defined (magnitudes 40 and 65); both respectively correspond to a minor and a major seismic alarm.

At the signal box on both tracks of the affected trip :

  • the detection of a minor seismic alarm leads automatically to a speed limit at 170 km/h,

  • the detection of a major seismic alarm leads automatically to the stopping of the runnings through the command of a global protection of the distance between two signal boxes, the information “red” is ordered.

Any detection is sent forward to the Atomic Energy Agency (CEA - Centre d’Etudes de Cadarache du Commissariat à l’énergie atomique), the CEA, according to the measures recorded by its own sensors, does - or does not - confirm an earthquake occurred, which might affect the considered zone within a maximum of ten minutes. The answer of the CEA (“confirmed alarm / non confirmed alarm”) is automatic and global.

  1. Wind across detection (DVL)

Because of the geographical situation of the Mediterranean HSP, the risk of train sets overturning under fierce wind across was studied. It was concluded that the conjunction of the 3 following factors may trigger it off: the speed of the trains, able to reach 300 km/h, the speed of wind across, able to reach 190 km/h and civil engineering works) of big height as well as a big amount of embankments adding to the speed of the wind.

The actions to take so as to reduce the risk are the following :

  • the setting-up of protections (windscreens) on the most critical sites so as to bring the effects of the wind to a level such as on other current points on the line,

  • the speed limit at 170 km/h, even 80 km/h, being triggered off by actions stemming from anemometric stations, regularly scattered on the other sites.

Each anemometric station includes :

  • two measurement posts, each of which is composed of two sensors (anemometers) and of two acquisition units,

  • two processing posts; the results provided by these posts are compared between each other so as to deliver consistent information to the signalling system (TVM - transmission voie-machine track to on machine transmission).

  1. Hotbox detection (DBC)

Monitoring of the temperature of the axleboxes on the trains running on an HSL is provided by a centralised hotbox detection system (DBC) located at the HSL control centre. The necessary information is fed into the system by local measuring equipment distributed along the HSL at an average spacing of 30 km. These monitoring points are equipped with temperature sensors that are kept on standby and activated whenever a train approaches. The temperature data is processed in real time by the central system and is recorded and stored to meet the needs of the rolling stock maintenance department. Comparison with the data from the previous detection point or the fact of reaching a critical temperature threshold can trip two types of signal :

  • A simple alarm (AS) for an axlebox whose abnormal temperature rise does not present an immediate danger but requires the box to be examined as soon as possible. The simple alarm has no effect on the signalling; it is dealt with by traffic control action taken by the traffic manager of the signalbox (stabling the train concerned on a passing loop).

  • A danger alarm (AD) for an axlebox that must be examined immediately. The danger alarm acts directly upon the signalling (TVM) by immediately posting the "all red" data item in advance of the presumed hotbox stopping point for three reasons :

  • To obtain a stop by service braking as quickly as possible, to attend to the problem train,

  • To reduce the speed to 80 km/h, in both running directions but without overlap, on the adjacent track in front of the hazard zone consisting of the block sections in which the (170) and (zero) data of the basic stopping sequence are displayed in the problem train,

  • To avoid stopping one or more following trains. This pile-up prevention function is designed to prevent an automatic, or manual, route-setting command from directing a train on to the track behind the problem train. In effect it prevents the markers for the route on which the problem train is present from going clear.

These arrangements are enforced until the driver of the problem train presses an alarm cancellation pushbutton located on the stopping marker post, after duly checking his train and clearing the situation with traffic control

  1. Ice and frost detection (DGV)

The presence of frost or ice between the contact wire and the pantograph can damage the wire or the pantograph, or both. Installing special detectors at the overhead line contact wire makes it possible to detect the risk that frost or ice may form. The ice/frost detection information is carried by the signalling transmission circuits between the crossover equipment rooms and the signalbox/control centre but has no effect on the actual signalling; only the substation controller uses this data, which allows him to take the necessary action (heating the OHL, advising drivers, etc.).

  1. Chemical alarm detection (ACH)

The chemical risk was considered for the Mediterranean HSP, because of the proximity of the Tricastin site. The aims of the measures taken for the protection of the TGV runnings against the hazards resulting of a toxic gas emission are to reduce the eventuality of a train sets’ stop near the site and, in case of alert, to stop and hold back the runnings outside the hazardous zones, while allowing the trains already entered in the zone to keep running. These measures also allow to identify the runnings which must be evacuated during the chemical alert. In case of the emission of a toxic gas, and because of the rapidity of moving of a gaseous cloud, it is urgent that the stopping measures are taken without delay. Therefore, the chemical alert is directly triggered off - through the activation of a switch - by the person in charge of this specific protection at the COGEMA; this action immediately and automatically affects the signalling system. So as to avoid untimely triggerings, the command circuit is doubled.

The automatic repercussion of a chemical alert on the signalling system has the following effects :

  • it stops and holds back the runnings in rear of the controlled zone, at the level of the last posts (according to the principle which consists in avoiding any piling-up of trains) as well as at the level of the last markers or signals giving access to the controlled zone,

  • it holds back in the controlled zone, the runnings stopped in rear of the zone to clear.

If the markers or signals are not already closed, the chemical alert controls their closing only if the part of track corresponding to their braking distance is free, so as to avoid an emergency brake.

  1. Dedicated rolling stock

The rolling stock for revenue service on very-high-speed lines, i.e. TGV trainsets, is composed of a new generation of fixed-consist electric trains equipped with special pantographs to collect current from the overhead line at high speed, with a braking system specially designed for the gradients of the HSL and with a modular onboard computer system.

A TGV trainset is made up of an articulated, non-splittable rake of trailer coaches with a power car on each end. Two such trainsets can be coupled together into a multiple unit to form a single train.

  1. The power car

Each power car acts as a locomotive, coupled to the rake of trailers by a conventional screw coupler. The aerodynamic "nose" has a built-in automatic coupler of the "Scharfenberg" type and an impact-absorbing shield that protects an ergonomically-designed driving cab. The power car can operate under both electrical power systems used on the SNCF network: 1500 V d.c. and 25 kV, 50Hz a.c. Some series (Eurostar) have been equipped with third rail current collection (shoegear) equipment. Others, such as Thalys and the joint fleets of the French-Swiss and French-Italian operating joint ventures are equipped to collect various currents used in Europe. The power car develops considerable power, about 4500 kW continuous rating for a weight of only 68 tonnes. Weight has been considerably lowered by the use of light alloy components (for the shield and the roof) and of high-strength, low alloy (HSLA) steel for the body frame. The design of the traction and auxiliary power equipment uses the latest power electronics. The traction motors – two per bogie – are fitted to the body. Their weight therefore does not affect the dynamic behaviour of the bogie, enhancing its stability and reducing the forces exerted between the wheels and the rails. There is a compulsory requirement for a limited axleload in all TGV designs to lessen infrastructure maintenance needs.

  1. The trailers

The principle of the articulated rake of trailers means first of all that fewer bogies can be used for a given trainset length, which improves streamlining and therefore reduces drag. It also affords better ride and overall passenger comfort : the seats are set at some distance from the wheels and thus also from the main source of noise. Thanks to the trailers' relatively low floor, passengers can board and alight more easily; there is a good amount of space between the trailers leaving space for a generously designed secondary suspension. The air springs of recent design exploit the possibilities afforded by the articulated connection between trailers (a connection specific to the design of the TGV trainset as an articulated set) to eliminate the damping links between coach body and bogie and transfer the damping of car body movements to the dampers interconnecting the bodies. This feature enables the movements of the bogie to be divorced as far as possible from the car bodies resting on them.

Articulation is also a real advantage in the event of derailment, even at speed: it prevents roll-over and pile-up of the trailers. The three derailments at full speed experienced to date only had minimal consequences.

  1. Braking with solid discs and microprocessor-controlled wheel slide prevention

The continual increase in top speed, the improvements in braking performance and a desire to eliminate the brake block-on-wheel technology (to reduce both cost and noise) have prompted SNCF and railway braking system designers and manufacturers to develop new brake discs with a much higher braking power than those of conventional locomotive-hauled trains; the new solid discs (referred to as "high-powered") afford the further advantage of serving as heat sinks and, since they are not "ventilated", also help reduce drag.

This improvement in braking performance was able to be effectively exploited by associating the new brake gear with automatic microprocessor control preventing wheelsets from locking and slipping at all times, more precisely by providing continual control, in real time, of the available adhesion from the wheel-rail contact; the braking performance can thereby be guaranteed in all train operating conditions.

  1. Current collection at very high speed

To collect current from the overhead lines at very high speed it is necessary to use a special pantograph that can absorb both large low frequency amplitudes and small high frequency amplitudes. Two-stage pantographs of the AM-DE type used on the South-East TGV from 1980 and the GPU type (for "Grand plongeur unique" or single, oversized head suspension) fitted on the Atlantic, Network, and North-European TGVs as well as on Eurostar from 1985 have therefore been developed. The advent in 1993 of the Cx (drag resistant) pantographs for use on the double-decker Duplex TGVs and the Paris-Brussels-Amsterdam-Cologne (PBKA) trainsets was a major breakthrough, since the springs in the second stage of the pantograph were replaced by an air cushion enabling the pressure of the bow on the contact wire to be electronically controlled. This new pantograph, with its highly improved aerodynamics, is less sensitive to crosswinds.

  1. The onboard computer system

The trainborne computer system manages the wheel slide prevention (WSP) system, monitors the brakes, adjusts the heating and air conditioning, controls the passenger doors and the exterior and interior destination and coach number displays. The huge influx of microprocessor technology signalled the arrival of new designs for the equipment monitoring, command and control circuits. The design is based on a vast onboard network, made up of microcomputers distributed throughout the trainset and connected together by a data communications loop itself linked to the ground-to-train radio.

With this system it is possible :

  • on one hand, to exchange information between the various items of train equipment, the driver (who works with the central onboard computer, located in the driving cab), the train manager (who can thereby readily keep passengers informed), as well as the operating and maintenance stations which can now communicate directly with the system and even send it certain commands.

  • on the other, to computerise troubleshooting on line by the use of a console with a VDU and a keyboard integrated into the driving desk in replacement of the traditional "hard copy" repair manual.

The computer system moreover allows nearly all the classic checklist operations to be carried out prior to train departure (brake and cab signal tests to mention only two). In traffic it supplies the driver and train crew in real time with everything they need to know about the operation of the equipment and signals any operating anomalies. This capability to detect failures en route is an important aid to maintenance, since it facilitates the requisite action at the next stop and therefore contributes to a significant improvement in fleet availability by limiting corrective maintenance and substituting preventive maintenance instead.

  1. HSL operating conditions

The first high-speed lines heralded the introduction of highly centralised, dedicated organisational systems. All signalboxes are remote-controlled from a single control centre. In the case of the first two lines built – the South East line and the Atlantic line – the signalboxes are of the "free-lever" type, the remote control of which is not duplicated. Therefore, if the remote control fails it is necessary to operate the local signalbox(es) locally. The substation power dispatcher controlling the electrical supply to the line has been incorporated into the central traffic control for the HSL.

This is why the train controller at the single control centre controlling the signalboxes (interlockings) over a range of several hundred kilometres at first appeared to cover both the "signalling" and "dispatching" functions and the name PAR, for "aiguillage" (signalling) and "régulation" (dispatching/traffic control), was therefore given to the single centre controlling the first French HSLs.

Starting with the commissioning of the new line northward from Paris (North European high-speed line), the local interlockings became computer-controlled all-relay designs (PRCIs) equipped with command and control modules (MCKTs). They are all remote-controlled from a single station via remote monitoring and control circuits. The local signalboxes are no longer equipped with local controls but all circuits are duplicated. Control of the electrical power supply to the line is grouped together with the power supply controls for the surrounding conventional railway lines. The power dispatching centre is located beside the PAR signalling and dispatching centre.

For the Lyons bypass of the Rhône Alpes HSL, the PAR was done away with and replaced by centralised traffic control installed in the Lyons traffic control centre.

The Mediterranean high-speed line is controlled from a signalbox of the conventional network (Cabin 1 at Marseilles) whereas the traffic control/dispatching centre is located at the National Operations Control Centre (CNO) at Paris Saint Lazare station.

The local signalboxes have solid state interlockings, called SEIs, controlled overall via a command interface (SNCI) but the various interlockings are actually set by a computer processing system, which drives the electric points motors, controls the cab signalling and all other signalling equipment.

The strategy regarding future signalling and dispatching centres consists of further computerisation by putting in place a Mistral-type route-setting command & control interface, the first implementation of which is used to control the 1180 possible routes of the new Cabin 1 in Marseilles, thus validating the decision to merge the conventional line and high-speed line control systems into a unified system that can be modulated to suit the volume of traffic to be managed.

Particular operating features of HSLs concerning track work :

An "automatic lookout" system called "protection management module" (MGPt) enables the procedures for obtaining authority to work and returning the track to service after work to be simplified by allowing direct communications with the gangs on the track via a voice recognition and synthesiser system.

Figure 4 :
The high-sped lines

SNCF’s « TGV » High-Speed Rail System by Gérard Boqueho, Deputy Director for Operating and Safety Systems

Каталог: Tokyo

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