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NEW APPROACHES IN RAILWAY SIGNALLING

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4 DIFFERENT APPROACHES

Automatic Train Track Switching System with Computerized Control from the Central Monitoring Unit

Standardization of CBTC Systems – Mixed Operation on Shared Linesin accordance with ERTMS/ETCS Standards

Cloud networks for ERTMS railways systems Future prospects on the intelligent monitoring

technologies for railway signalling systems in China

AUTOMATIC TRAIN TRACK SWITCHING SYSTEM WITH COMPUTERIZED CONTROL FROM THE

CENTRAL MONITORING UNIT

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A rail track switching system has been designed to control railway track controlling devices including railway switches and signals within a given area from a single point. Such control is exercised through the use of various track circuits which detect the presence of trains on a particular track and monitor the train’s safety from a central room. The system secures the safety standards as well as economical and beneficial switch and signal control within a distance maintaining reliability, sensibility and precision. This research is based on microcontroller to reduce the complexity and cost. A low power dc motor is used as a track switching device. In the sensing unit photodiode is used for detecting IR radiation which ensures a reliable detection of trains’ entrance. A communication line communicates between the track switching device and main monitoring room. Total system can be monitored and visualize by a software which shows train’s position, operation mode and safety status. This system can work both automatically and manually and also can be controlled by the software from the main control room which gives the system more flexibility in operation.

Introduction

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The Goal of This Research

In this research, the soul idea was to design a system to avoid the head on collisions of trains due to either disoperation or maliciousness. The system will work automatically and send the information to the central control authorities for further processing. Some sensors have been used to detect the train position and communication line to communicate from the rail track to the main control room. Software will monitor and maintain the whole process to secure the safety of the train. By analyzing cost, efficiency, reliability the system is found better than the existing system.

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System OverviewThe block diagram of the system shown in Figure 1 has four sets of IR transmitter and sensing unit, two of them has been used to detect the entrance or leaving of a train at certain junction (here the track switching point) on one side and the other two sets are used for same on the other side. The two sets of sensor provide data for determining the direction of train course. The others associate block diagrams are depicted in Figures 2 and 3. Based on the signals from the sensors, microcontroller sends the control signal to the track switching motor which switches the rail track to bypass a train in other track to avoid collision. Again there is a provision for manual control of this track from the control room (here, the PC).

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Total block diagram integrated with different parts has been shown in Figures 1, 2 and 3. The system is designed for a particular track, if the real implemented system arrangement is complex then the system block and circuit diagram will be different but the main idea will be similar.

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Sensing Unit The IR led and the photodiode are the heart of a sensing unit. When no train passes through the sensing unit, then photodiode exposes to IR light which causes photodiode to conducts photocurrent and a low voltage across the diode causing the output of the comparator to be high [5]. When train passes through the sensing unit, then IR light is interrupted and photodiode generates voltage proportional to the intensity of the light and finally made a comparator output [4, 6]. The detail circuit of all the four sensing units is depicted in figure 4. The circuit diagram of each sensing unit is depicted in the following Figure 5.

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System Working Process When a train passes the up sensing unit then the entrance information is stored in microcontroller. If the train is outgoing (out of the junction) the procedure is repeated. If the train is incoming (into the junction) then the down sensing unit status is checked. If the train is outgoing at the down sensing unit, then the operation is again repeated. Otherwise if the train is incoming, while it ensures that two trains are on the way in face-to-face direction, microcontroller sends the information to the pc. If the pc control software is configured as automatic then microcontroller sends signal to the track switching motor to switch track. If the pc control software is configured as manual then microcontroller waits for the controller personnel response and operates accordingly. The overall flow chart of the system is shown in the following Flow Chart. A prototype implemented model (shown in the figure on the right) has two sensing units: Up sensor unit and down sensor unit, also has a track switching unit. Two units separately sense the train’s position on a particular track on a particular time. If both sensors sense that the two trains are in a same track then the control software sends signal to the track changing motor to bypass one train from another. Here, track switching should consider about the single track, if the train line is single track then how train will bypass. At that case, have to find the nearest train station where has two line and sensor arrangement & software algorithm should make in a way so that in a particular distance finding that station the trains bypass each other.

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When the two trains are on each of the tracks, the sensors detects it and send information to the control software. If the control is in ‘auto’ mode (in the Figure below) then the track is automatically switched to bypass one train on the other track.

In case of ‘manual’ mode this automatic track switching is restricted and the track switching solely depends on the control software instruction. In this mode when software gate option selected ‘close’ (shown in Figure 10), the track remains on its normal position. When the gate is in ‘open’ the track switching motor operates and the track is switched to other position. This condition is shown in Figure 11. In both mode ‘auto’ & ‘manual’ the sensor information is carried to the software window so that the operator has always the indication of the track condition. The control software has another exclusive feature: if any how the control circuit is disconnected from the control PC the software window will indicate it (as shown in Figure 12) and thus the operating authorities can take measures to find the causes of disconnection and will take the necessary steps to recover the system. Though the disconnection from the PC, if the remaining circuits is ok then on emergency condition automatic operation will perform.

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Manual Mode

In case of ‘manual’ mode this automatic track switching is restricted and the track switching solely depends on the control software instruction [11]. In this mode when software gate option selected ‘close’ (shown in Figure 10), the track remains on its normal position. When the gate is in ‘open’ the track switching motor operates and the track is switched to other position. This condition is shown in Figure 11. In both mode ‘auto’ & ‘manual’ the sensor information is carried to the software window so that the operator has always the indication of the track condition. The control software has another exclusive feature: if any how the control circuit is disconnected from the control PC the software window will indicate it (as shown in Figure 12) and thus the operating authorities can take measures to find the causes of disconnection and will take the necessary steps to recover the system. Though the disconnection from the PC, if the remaining circuits is ok then on emergency condition automatic operation will perform.

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The Implementation and Considerations

A prototype of the proposed system has been implemented. For the practical implementation in the railway, some components should change. The sensor parts may consider as requirement of the situation. Here, IR sensor has been used, except this strain gauge or laser or other sensor can be used according to the situation. The main software and other components will function well with all sensors. For implementation, one should consider the single line of the railway and how one train will bypass from other in that line. In this implemented system the software algorithm and sensor arrangements are in such a way so that the train will bypass after coming to the dual track position (as it is known that in the rail line after two/three km has track crossing system). So according to that condition the software algorithm and sensor position should arrange and by this proposed system’s software it can be easily arranged. If the distance between the track switching system and the control room is far then fiber optical cable or GSM communication or railway signaling line can be used. This arrangement can be a scope for the further research of the proposed system.

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The implementation of this automation rail track switching system with computerized control can provide safety to ensure the convenience of railway technology. This research can be used as a safeguard for human life and wealth by avoiding train collision which frequently happens due to wrong operation and mismanagement. It can be implemented easily with less cost and complexity. But some factors like sensor and component selection may be changed according to the environment and situation or desire. According to the specific route or rail track design, some feature of the main controlling software may need to change which can be easily done by this software. In all cases the main features will work similar the implemented prototype. The implementation of the proposed system will contribute a lot in automation of the railway system which will minimize great financial losses as well as the human woe.

Conclusion for Automation Rail Track Switching System

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Standardization of CBTC Systems – Mixed Operation on Shared Lines

in accordance with ERTMS/ETCS Standards

Megatrend urbanizationThe numbers are self-explanatory. In 1800, only three percent of the world’s population lived in cities. 2007 was a milestone in human history: for the first time ever, more people on earth lived and worked in cities than in rural areas. The UN estimates that the proportion of city-dwellers will climb to 61 percent by 2030, pushing up urban population from three billion today to a total of five billion. And only a few of the twenty biggest megacities with populations over 10 million will be in industrial nations; the others will be in threshold and developing countries. By 2015, some 350 million people will live in these megacities. As a consequence, accelerating urbanization and economic growth will fuel a massive demand for adequate infrastructures such as energy and water supplies, and transportation.At the same time, the cities’ economic attractiveness will continue to grow. Even today, cities such as Dhaka, Cairo, Seoul, Buenos Aires, Mexico City and Tokyo already generate between 40 and 60 percent of their respective country’s gross domestic product (GDP).

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Findings of a stakeholder research project supported by Siemens

Siemens has recently supported a research project conducted by GlobeScan and MRC McLean Hazel into megacity challenges. The methodology of the research was based on a stakeholder survey covering 25 cities and metropolitan areas with, on average, approximately 20 interviews for each city and area.The cities and metropolitan areas chosen where defined as “megacities” in accordance with thedefinition of the United Nations and were selected on the basis of being the most populous cities inthe world.The respondents came from four stakeholder groups: elected politicians, employees of themunicipality, private-sector infrastructure providers and people in a position to influence infrastructuredecision-makers.According to the stakeholders in urban development and transport, the continuous and sustainable growth of city regions and economies constitutes a major challenge for the infrastructure, demanding efficient transport management and planning.These sprawling conurbations are creating new urban dynamic forces. Commuters frequently travel large distances from densely populated suburbs or other cities nearby.Sustainable urban development calls for a high level of efficiency of the existing infrastructure for a holistic approach to the challenges at a metro-regional level.These demands require a transportation system that can be operated independently in the inner city area and integrated into a rail network serving the wider metropolitan area.

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Complying with International Standards

Meanwhile, many railway operators worldwide are already moving from a national standard to an international standard that will allow unrestricted cross-border traffic. The leading standard for national railways is the ERTMS/ETCS standard. Most existing rail networks have been in service for decades and many national train operators are concerned to revitalize the existing infrastructure.With a high-quality infrastructure in place, the challenge has shifted toward coping with the need to renew aging systems or dealing with obsolescence where the installed infrastructure no longer meets operational requirements or changing service expectations.

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Maximum flexibility in the urban transport networkThe transport needs in booming conurbations are continuously growing. People are constantly on the move, whether on their way to work, traveling to leisure or educational facilities or while shopping or returning home. Efficient mass transit systems are therefore key to achieving maximum mobility in cities and large urban areas worldwide, promoting urban and regional economic development.Efficient mass transit systems that can be easily adapted or upgraded to the increasing transport capacities are required for maximum mobility. The public transportation systems in inner cities and urban areas must support the growing demand for convenient and time-efficient urban and suburban services.The performance of mass transit systems is largely dependent on the performance of the automatic train control (ATC) system deployed. With increasing automation, the responsibility for operations management is passing from the driver and operator to the system.An ATC system incorporates functions for the monitoring, operation and control of the entire operational process. It can feature different degrees of automation such as manual train operation with a driver, semi-automated train operation and driverless operation. An ATC system displays the current driving instructions on the cab console and supervises the permissible train speedcontinuously. Color-light signals can thus be dispensed with in the higher levels of automation. The functional scope of ATC systems is focusing more and more on cost reduction.The most important qualities demanded by train operators are:• safety• performance• cost-effectiveness• maintainability• upgradability• scalabilityThe ATC system should be designed on the basis of the latest technologies available and comply with international standards. Only if this approach is integrated into the system development, can it be guaranteed that the ATC system will be future-proof and support the operators, municipalities and governments in fulfilling their obligation to provide an attractive transportation system for day-to-day riders.

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Technologies to meet modern rail transport requirements

The state-of-the-art technology of communication-based train control (CBTC) systems meets the operational requirements for safety, performance, quality and reliability for high- and medium-capacity metro systems. However, the CBTC systems of the various system providers are mostly unique in their system architecture and have been designed neither for mutual operational compatibility nor for compatibility with national railway networks.In some areas, it is economically or environmentally necessary to employ mixed operation, for instance where metro systems serving the inner city and suburban railways serving the greater metropolitan area share the same tracks.Metro operators and national railway operators prefer a unified operational concept and demand maximum operational safety. Operation on such lines should be at least under ATP supervision and should prevent accidents caused by human failure in the case of manual train operation.There are currently no independent standards defining functional requirements for interoperability with ERTMS/ETCS standards to be satisfied by a CBTC system. Standardization will enhance performance, availability, operations and train protection, and permit new CBTC applications.Both the CBTC system and ETCS system need to have fixed and switchable balises for train locating and track-to-train communication. Balises are passive transponders powered by the passing trains. When a train goes over one, it transmits a safety-relevant telegram to the on-board subsystem, which identifies the balise and allows its position to be determined in the rail network with the aid of the onboard track database. Switchable balises transmit a safety-relevant balise telegram, which also contains the movement authority, to the train's on-board subsystem, which reads the balise information and reacts to it.Communication between the wayside balises and the on-board balise subsystem is via the air gap inaccordance with the data package specifications from UNISIG.In this paper a detailed technical proposal is presented for the standardization of CBTC systems based on the ERTMS/ETCS standard. The proposal focuses on the ETCS Level 1 standard.

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Interoperability principlesConsensus-driven approaches take a long time to reach a common specification. In the case of the standardization of ERTMS/ETCS in Europe it was approx. 10 years before the first common version was agreed. Even now, work on it continues, with all the major countries concerned having their own test and pilot projects and introduction strategies.As one of the world leading suppliers of signaling systems with our more than 100 years' signaling experience, Siemens is active in all major working groups such as the European MODURBAN group, the international IEC T9 working group 40, UNISIG etc. for the standardization of mass transit systems.According to IEC 62290-1:2006 [3], "interoperability refers to the ability of a transport network to operate trains and infrastructures to provide, accept and use services so exchanged without any substantial change in functionality or performance. This ability rests on all the regulatory, technical and operational conditions which must be met in order to satisfy all the defined requirements applicable to the given grade of automation taking into account grade of line, irrespective of which supplier provides which components or systems."The interoperability subsystem characteristics can be evaluated by reference to a common international standard or other relevant documents, independently of the system in which the constituents are to be integrated.Interoperability subsystems can be designed and developed individually. The easiest point at which to implement interoperability is the train-to-wayside air-gap interface.Air-gap links between the wayside and on-board equipment can be by means of continuous or intermittent communication channels.Hence the most useful ATC system is one that can provide open standardized interfaces at the balise interface and radio link interface.

Trainguard MT, with its modular system architecture, is the ATC product developed by Siemens to the latest standards to meet both present-day and future interoperability needs.

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Continuous train control using CBTC systems

For the most efficient operation, the ATC system concept must be based on the moving-block headway principle implemented by a cyclical exchange of position report telegrams sent from the trains to the wayside subsystem and of movement authority telegrams from the wayside subsystem to the trains.

The wayside subsystem calculates the movement authority on the basis of interlocking statuses andtrain position reports. The on-board subsystem supervises train operation within the dedicatedmovement authority limits.

The wayside and on-board subsystems use a track database (TDB) containing the track topographydescription. The TDB consists of linear segments each with a certain length, adjacent segments anddescriptions of additional information such as speed and gradient profiles. Thus, if the TDB isavailable on board, there is no need to transmit all this information via the communication channel. This enables the necessary bandwidth of the radio communication system (RCS) to be reduced.

The on-board subsystem supervises and controls train movements based on its train locating function,the information received from the wayside subsystem and information stored in the TDB.The operation of the ATC system described is designed according to the principles laid down in thecurrent standards.

Provided the trains and wayside have the appropriate equipment, the system can be operated at levelof automation 3 (GoA3) or 4 (GoA4) as per IEC 62290-1:2006.

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Intermittent train control (ITC)

Intermittent train control operation is based on the fixed-block principle. The headways are ensured bythe interlocking using conventional route monitoring (clear signal aspect when all the necessaryconditions are met permitting a train to enter the section in advance of the signal).

A lineside electronic unit (LEU) is connected to the signal to select the switchable data balisetelegram information in accordance with the signal aspect. If the signal clears, the switchable balisesends a movement authority telegram to the on-board subsystem while the train is passing the balise.

The on-board subsystem uses a TDB as described for continuous ATC. Based on the TDBinformation and movement authority received, the on-board subsystem supervises and controls the train's movements in accordance with the train's location.

Intermittent ATC is used as a simple interface to, as well as an overlay system for, existing signalingsystems. If required by the railway operator, existing interlockings and signals can be used inrefurbishment projects to avoid operational disturbances.

The architecture of the intermittent train control system can be extended for continuous ATC at a laterstage.

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Intermittent train control (ITC)

In intermittent ATC, as well as continuous ATC, the system relies on the interlocking functionality forsafe route management (e.g. route locking, route setting, route release) even if all the trains areoperated at CTC level.Interlocking overrides, allowing a different signal aspect (or cancelation of a signal aspect) to bedisplayed to CTC trains, are sent from the wayside subsystem to the interlocking, for instance.

For maximum flexibility, it may be necessary to have the ATC system operating at different traincontrol levels and in multiple train operating modes. The levels and modes depend on both theequipment of the territory where the train is currently running and the equipment available on board the trains.

Provided the trains and wayside have the appropriate equipment, the system can be operated fromGoA0 to GoA2 in accordance with IEC 62290-1:2006.

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System interfaces for train-to-wayside communication

The ATC system is embedded in its environment with its own logical interfaces and components. For mass transit applications two communication methods can be distinguished.

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Continuous ATC in accordance with CBTC standards

For data transmission, the ATC system uses the data communication system (DCS). This communication channel allows bidirectional communication between the wayside subsystem and onboard subsystem. The DCS acts as a transparent data channel between the two subsystems. The ATC system has a logical interface to the DCS to support the RCS function.The on-board subsystem provides the DCS with information about the train's position. Although theDCS will work without it, this information can improve the DCS's availability.

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Intermittent ATC in accordance with ETCS/ERTMS standards

For the train-to-wayside intermittent communication, the ATC system uses Eurobalises at the wayside as well as a balise antenna and balise reader on board the train as specified for ETCS level 1 (UNISIG Class 1 System Requirement Specification 2.2.2). This standardized Eurobalise communication channel allows unidirectional data transmission from the wayside subsystem to the on-board subsystem via all balises. The balise telegrams for the ATC system are specific to the mass transit application and conform to the ETCS balise interface specification. They are embedded in ETCS packet 44 (“data used by applications outside the ERTMS/ETCS system”).

The information provided to the on-board system by switchable-data balises comprises:• balise ID• balise version• movement authority

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Safe train separation at ITC level

A safe interval between trains and ATP at the ITC level depend on fixed blocks that are interlocking routes delimited by signals whose aspects are controlled by the interlocking. The routes generally correspond to a stretch of track between two signals.The underlying interlocking in the ITC displays a proceed aspect only if the entire route up to the next signal and an optional overlap are determined to be clear by the track vacancy detection system.The switchable balise connected to the LEU sends the ITC movement authority (ITC_MA) derived from the signal aspect. In Trainguard MT (TGMT), deterministic and non-deterministic movement authorities can be distinguished.An ITC_MA is valid from the position of the main signal balise up to the point of protection (POP) relative to the next main signal (e.g. track vacancy detection section boundary).

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Deterministic ITC_MAThe deterministic ITC_MA is used if the next main signal can be derived unambiguously from the signal aspect.A deterministic ITC_MA defines one vital and one non-vital movement authority limit (MAL) and extends up to fixed target points (end of track, signal etc).The non-vital MAL defines the location at which the train is required stop operationally.

The non-vital MAL is configured some distance in rear of the next main signal balise. In case the infillbalise does not provide an ITC_MA corresponding to "signal shows proceed aspect" or no infill baliseis present, the train is brought to a stand in front of the main signal balise.A deterministic ITC_MA is delivered with TGMT packet 2. This balise telegram provides vital and nonvitalMALs and the positions of all facing points within the ITC_MA path.If the signal does not show a proceed aspect, the on-board subsystem will get an ITC_MA with zerolength, causing it to trigger emergency braking.Note: The handling of ITC_MAs is the same as for CTC_MAs.

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Non-deterministic ITC_MA

The non-deterministic ITC_MA is used if the next main signal cannot be derived unambiguously from the signal aspect due to unknown point positions in the ITC_MA path.Hence, the non-deterministic ITC_MA specifies only the “known” part of the path to the destination and the maximum path length to the possible (expected) repositioning balises.For ATP speed supervision, the on-board subsystem determines the most restrictive speed profile and the worst-case grade of all possible paths up to the possible repositioning balises.The on-board subsystem monitors the detection of a repositioning balise up to the maximum path length to the possible repositioning balises. If no repositioning balise is detected within this maximum path length, the train location status becomes 'delocalized’.

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ITC_MA received from repositioning baliseWhen the train passes over a repositioning balise, TGMT packet 4 is received and the nondeterministicITC_MA extended as a deterministic one.

Initial situation:• Signal S1 shows a clear aspect because it has received information about the locked route. Aroute is set from S1 to S21.• Signal S1 can determine whether track 3 or track 1/2 is locked but is unable to distinguishbetween track 1 and 2.• In the situation described, the route is set to track 1.Balise A contains the following information:• TGMT packet 1• TGMT packet 3, which contains the point status "left" of P1, point status "unknown" of P2 anddistance to the farthest repositioning balise.Balise B1 contains the following information:• TGMT packet 1• TGMT packet 4, which contains the valid ITC_MAL (position of the protecting points assignedto S21).

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Sequence of steps in the example:

1. The on-board subsystem receives a non-deterministic ITC_MA from balise A.2. The on-board subsystem determines the lowest grades and speed restrictions for the alternative paths via track 1 and track 23. The on-board subsystem expects either balise B1 or B2 as a repositioning balise.4. The on-board subsystem receives the repositioning information from balise B1. From then on,the on-board subsystem supervises a deterministic ITC_MA from S1 to S21.

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ITC_MA received from infill baliseThe ITC_MA received from an infill balise merely extends the existing ITC_MA. The ITC_MA of theinfill balise is only valid in advance of the associated main signal balise. The area between the infillbalise and associated main signal balise is not covered by the ITC_MA of the infill balise.Thus, infill balises can only be used to extend ITC_MAs already received, not to perform a leveltransition to CTC.

Infill balises extend existing ITC_MAs any distance in rear of the main signal balise. In order to ensure that the ITC_MA extension by the infill balise is still valid at the location of the associated main signal balise, however, the on-board subsystem must check the validity of the ITC_MA extended by the infill balise and that the balise information of the main signal balise is read.Provided the trains and wayside have the appropriate equipment, the system can be operated at level of automation 2 (GoA2) as per IEC 62290-1:2006.

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Validity of an ITC_MA extended by an infill baliseAn infill balise extends an existing ITC_MA based on the next activated route ahead. As a cancelationof the next route cannot be excluded, however, the ITC_MA received by the infill balise is not valid foran unlimited period of time. The ITC_MA received by the infill balise is discarded if its currencyexpires or the train comes to a stand between the infill balise and next main signal balise. In case of adiscarded ITC_MA, the on-board subsystem supervises the previous ITC_MA up to the main signalahead.

Supervision of the main signal balise at ITC levelAt ITC level, the on-board subsystem supervises the detection of a main signal balise. If an expected main signal balise is not read, the on-board subsystem initiates emergency braking and performs a transition to the next lower level of automation (manual train operation using the interlocking).The reading of a main signal balise is always supervised at ITC level, independently of the receptionof an infill ITC_MA.

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Operational versatilityOperational versatility is one of the essential benefits of such a state-of-the-art ATC system.A wide variety of situations exist where differently equipped vehicles, various communication methodsand multiple operating modes can coexist on the same line, requiring the operators to be extremelyflexible in their operation of the system.

The following key characteristics demonstrate the benefits of such an ATC system:- Mixed traffic, - Mixed operation,- Performance, modularity and scability, - Reduced operation and fall-back mode,- Interchangeability, - Expandability.

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Mixed Traffic

The term “mixed traffic” is applied to the operation of trains equipped with the ATC system automatically and simultaneously with unequipped trains (no on-board equipment, e.g. engineeringtrains, or incompatible on-board equipment) in the same territory.

Thus, the range of each train is extended and different trains can be controlled in a mixed traffic environment, be they mainline, suburban or freight trains. Thus, the infrastructure can be utilized in a highly efficient manner.Unequipped or incompatibly equipped trains to be operated on the main line can run on the lines using the traditional wayside signals and equipment. By following the indicated signaling and rules foron-sight running, the driver can still operate the train safely on the basis of clear information.

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Mixed Operation

Vehicles equipped for continuous communication to ensure short headways in moving-block operation on inner-city lines can change over seamlessly to intermittent communication on suburban lines equipped accordingly.

Switching from continuous to intermittent communication takes place automatically. This can also increase system availability during migration phases or when upgrading an existing train fleet or signaling system.

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Performance

Thanks to the versatility of the ATC system described, it is possible to have moving-block and fixedblock functionalities in a single system. As the system supports both train control levels, it can provide greater flexibility for railway operators to meet their respective transportation needs and hence offers far more than a normal CBTC system.

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Modularity and scalability

The ATC system is a scalable system with an innovative modular design. Its software and hardware components incorporate the latest standards and interoperable interfaces to ensure compatibility with existing subsystems.

The modular design also ensures that up-to-date hardware and software innovations can be implemented smoothly when updates or improvements are required.

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Upgradability

The ATC system can be upgraded from fixed block to moving block. This enables headways to be reduced to meet present and future requirements.Moreover, both the level of automation and the performance can be upgraded. A performance upgrade depends on the chosen method of communication. The level of automation can be upgraded from manual through semi-automated to driverless train operation.A line equipped with this ATC system can easily be extended to include more stations and trains.The upgradability of the ATC system ensures optimum investment protection.

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Reduced Operation and Fall-Back Mode

The ATC system is designed with various redundancy and fall-back levels so that, in the event of a partial failure, operation can continue without any loss of performance or degrading.

Radio failures and brief losses of communication have no effect on safe train operation. The movement authority and train position are valid as the location is calculated independently of the communication channel.

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Interchangeability and Expandibility

The ATC system offers open and standardized interfaces for train-to-wayside communication. This unique advantage will allow operators of the system to standardize their system requirements, which will in turn enable manufacturers to offer interchangeable system solutions.

Once in operation, the ATC system will also meet the future requirements for network growth and help reduce operational investment.

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Cloud networks for ERTMS railways systems

This new paradigm about the execution of the ERTMS management activities taking advantage from cloud networks. It suggests to distribute among cloud resources the computational load due to the elaboration of the collected data and the derivation of required commands for trains and actuators. This can make possible a proactive approach to the trains management, suitable not only to consider the datasent by the trackside equipments, but also the informationdirectly collected onboard of the train. Despite trackside dataare considered by the management system, actually they arenot integrated with onboard real-time data that are sent tothe ground system for diagnosis purposes. These two sourcesof information can be jointly used to simulate in advance thetrain transit, deduce possible delays and anomalies and moreefficiently manage the trains circulation.

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ERTMS functional architecture.ERTMS is based on a complex architecture suitable to monitor the trains and thestate of the railways and to provide all information required to accurately schedule the trains transit and manage trackside devices, elaborating the required command for trains and trackside equipment

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Basic Functional Blocks of ERTMS Level 1

The data are collected by means of information points that work as ‘sensors’ distributed along the railways lines to monitor the state of the infrastructure and the circulation of the convoys and deriving information about position(Eurobalise, Line Side Electronic Equipment LEU, Track Circuit, etc.) and conditions of trains (bushings temperature detector, axles counter etc.). Some of these devices also deal with the exchange of information between the train and the management system, such as Eurobalises that are installed along the railways lines and forward to the ERTMS train onboard equipment the telegrams about the state of the linereceived from the management system through the LEU. At its turn the management system is responsible of all the elaboration needed to control the trains circulation and to derive the commands for trains and trackside actuators, such as railroad switches, light signals and semaphores suitable to regulate the circulation of railways convoys. In particular, currently the management system is hosted in the CentralControl Rooms that centrally manage and supervise trains traffic of different geographical areas.

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The mentioned operations require an accurate exchange of information between trains, trackside equipment and elaboration components: data about the running trains (such as trains state, speeds and position), failures of trains, railways, trackside equipments etc. are collected and the required actions (for instance maintenance and repairs) and commands are elaborated.In the new idea about the execution of the ERTMS management activities taking advantage from cloud networks resources is proposed. Indeed, cloud networks introduce a disruptive idea of access and use of computational and network resources and a contact point is possible if the use of cloud resources is introduced in the railways management systems.

ERTMS Management Requirements

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The Goal and The Advantages of the Idea

The idea is to distribute among cloud resources the computational load due to theelaboration of the collected data and the derivation of commands for trains and actuators. This can make possible a proactive approach to the trains management, able not only to consider the data from the trackside equipment, but also the information directly collected on the trains. Indeed, despite trackside data are already considered by the management system, actually they are not integrated with onboard real-time data that are sent to the ground system for diagnosis purposes. These two sources of information can be jointly used to simulate in advance the trains circulation, deduce possible delays and anomalies and more efficiently manage the trains transit. As the best of our knowledge the possible intersections between cloud networks and railways management systems has not yet been deepened, except some hints to security issues.Some possible applications of this model are suggested as explanatory examples. The first one is about the implementation of ERTMS EURORADIO communication protocol, then the RadioInfill function supported by EURORADIO in ERTMS Level 1 [10] is evaluated. Finally, the focus is extended to the ground components of ERTMS and, then, to the new implementations of ERMTS based on radio communications (ERTMS Level 2 and Level 3).

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Further Details…

The suggested idea is to migrate the execution of the upper layers, Session ad Application, in the Cloud, for instance in a cloud private to the railways operator. The aim is to reduce the onboard computation and to extend the data elaboration in order to derive additional information and aid the management process. Indeed, making cloud computational resources accessible by the management system and the availability of onboard data about train state, speed and position and devices failures can suggest further elaboration on data collected onboard. Currently these data are used on the train and are periodically sent to the ground system for diagnostic purposes, whereas information about position and speed are derived by trackside devices and corrected through Global Positioning System (GPS) information. Instead the availability of such kind of information in the cloud, directly accessible in realtime by the management system, can permit to refine the computation and to introduce new services. For instance, it should be possible to simulate in advance the transit of the train, computing its next position-time data. Moreover, combining these data with information about railways lines provided by trackside devices (for instance about failures of railways or other trains in movement), should make possible to update in real-time the train driver about the required actions to perform (deceleration or stop). This idea is in line with the approach behind the RadioInfill function provided by EURORADIO, that faces off the lack of responsiveness typical of discontinuous ATP systems, such as ERTMS Level 1. In particular, RadioInfill has been implemented at the application layer.

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ERTMS System in Cloud

Identified the different functional blocks where the management activity is executed, it is possible to imagine to migrate or replicate the corresponding computation in the Cloud, taking advantage from the availability of overperforming computational resources that can be directly accessed be the different involved actors. For instancelooking at ERTMS/ETCS Level 1 system, illustrated in the next figure where the points of interest are highlighted in red, proceeding from the trackside intelligence to the centralized one, most of the activities of the Signal Manager-Radio Infill Unit (SMR), that receives the information from the LEU, should be processed by cloud resources. GSM-R. The migration of the computation or part of that performed by these units on cloud resources, accessible to RIU-M, SMR and onboard unit can foster the rapid update of information and improve the efficiency of the management system.

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ERTMS Functional Architecture

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Conclusions

Finally, in ERTMS Level 2 and 3 the progressive migration to exclusive radio communications implies that the system will no more deal on trackside devices whose number and type can be reduced. This involves an increasing weighting of the role of the information systems in the railways management, suitable to elaborate the data sent by both trackside and onboard equipment, deriving further required information and the consequent commands. This can promote the use of cloud resources.Cloud networks are a current interesting evolution of information science introducing a disruptive idea of access and use of computational and network resources. In this position paper the use of cloud resources is introduced in the context of railways management suggesting the replication or the migration of the computation from the physical railways entities to the cloud. Some landmarks for the introduction of cloud networks in ERTMS systems are drawn taking into account the EURORADIO protocol, the RadioInfill function of ERTMS Level 1. Finally, the ERTMS system as a whole is investigated identifying some interesting areas of intervention.

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Future prospects on the intelligent monitoring technologies forrailway signalling systems in ChinaThis is a survey on the current development, underlying issues, and the future prospects associated with China railway signalling monitoring technologies. To overcome the problems involved such as interconnection, data sharing and intelligent analysis, an integrated scheme of the intelligent monitoring and maintenance system for railway signalling systems is further presented. In this scheme, all kinds of monitoring data are centralized to conjointly and intelligently analyze the status of signalling devices.Moreover, interacting with the maintenance managementsystem, the integrated scheme will have the functions ofmonitoring, diagnoses, intelligent maintain and management,which will greatly improve the usability of railway signal.Finally, some principles and precautions are pointed out in thefuture construction of the proposed scheme.

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Introduction

To monitor the operational status of railway signalling systems, various monitoring and recording devices have beendeveloped. However, most of the monitoring systems can notbe connected each other. In other words, they are independentmonitoring systems and massive valuable monitoring datacan’t be shared effectively to help to detect operational faults.In fact, fault diagnosis and maintenance programs mainly relyon human experience at present. With the more and moreapplication of the advanced signal equipments, maintenancehas even been becoming more difficult than before.Therefore, the intelligent and comprehensive fault analysisand health prediction of signalling systems need to beconsidered to improve the maintenance performance.

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Present Situation of Railway SignallingSystem Monitoring Technology

1.1 Train Control system in ChinaIn China, the railway signalling network is being achieved gradually. As the systems of Chinese Train Control System Level 3 (CTCS-3) for example (see Fig.1), waysideequipments, computer interlocking (CBI), train control center (TCC), radio block center (RBC), temporary speed restriction server (TSRS) and centralized traffic control (CTC)) are interconnected to transmit train control data through signalsecurity data network (SSDN). Moreover, onboard devices send train location information to RBC, whereas the Movement Authority (MA) is delivered from RBC to onboard devices using Global System for Mobile Communications-Railway (GSM-R). Each communication and signalling equipment runs independently but transmitslarge amounts of real-time data to each other through a communication network.

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Lineside Structure of Lineside equipments of CTCS-3

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Monitoring subsystems for CTCSTo monitor real-timely the operation of on-board signalling equipments, Chinese HSR has equipped with DMS (Dynamic monitoring system) which consists of on-board information detecting equipment, ground data centre and inquiry terminal. The on-board information detecting equipment collect data from ATP, Balise, track circuit and RBC, and then transmits them to the ground centre through GPRS/GSM-R/WLAN network (Figure 2). Through this remote monitoring method, the ground centre can monitor and deal with the working states and faults of on-board signal equipments.

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Railway Signalling System Monitoring TechnologiesAnalysisIn China, although a lot of works around system monitoring and maintenance have been carried out, there are still some problems as follows:1- Lack of interconnection among different monitoring systemsCSM is the core of China's railway signalling monitoring equipment based on station interlocking. It is installed in station’s signalling mechanical room, and mainly monitorselectric parameters, on-off state of switch, signal, track circuit, signal cable and power supplies, and monitoring information from ZPW-2000 and TCC. But CMS can not obtain the monitoring information from RBC maintenance terminal and DMS. When train control system fails, it is generally difficult to judge which part of the on-board equipment, ground equipment, station equipment or the RBC failure is failure. In other words, it is infeasible to achieve comprehensive and intelligent fault analysis based on the seperated monitoring data.2- Communication and signalling monitoring data are not sharedIn CTCS-3 train control system, GSM-R wireless communication becomes an indispensable part to undertake ground-train information transmission. Currently in the process of high-speed railway operation, the phenomena of GSM-R communication timeouts and offline occuroccasionally, which affect the normal operation of HSR. Because communication and signalling monitoring data are not shared, it’s difficult to make accurate analysis and localization of failure, like GSM-R transmission equipment failure, radio interference, on-board signal or ground signal equipment failure.

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Railway Signalling System Monitoring TechnologiesAnalysis

3- Lack of intelligent analysis and prediction of the device healthAt present, the railway signalling monitoring systems have stored a large number of historical monitoring data. But the effective data mining for historical data and utilization of intelligence analysis software are far from enough. The signalling equipment faults can’t be accurately analyzed, and the forecasting and early warning of the device health can not be done.4- The monitoring and maintenance management are not integratedThe signalling monitoring system does not integrate with signalling maintenance management system. In this circumstance, the fault detected by monitoring system can not be forwarded to the maintenance management system and dispatching system. The maintainer can not be dispatched directly to the fault spot, and the repair piece can not be utilized efficiently. Therefore, such disintegration reduces themaintenance efficiency and the product configuration capacity as well.

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Intelligent monitoring technology scheme ofrailway signalling system

The business logic of integrated signalling monitoring system includes data acquisition, storage and analysis, and production command, as shown in figure below.

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Working Process of the SystemThe main function of data acquisition part is data sampling and aggregation. As the integrated monitoring platform of railway signalling equipments, it integrates all of signalling sub-systems which have self-diagnostic function, and achieves the overall state monitoring and maintenance of the signalling equipments.Based on the data acquisition, the storage and analysis part mines and analyses equipments statement and running status data of all related systems comprehensively.And it can realize the early warning analysis and intelligent fault diagnosis of equipment characteristic parameters, compress the fault delay of signal equipment effectively, and improve the pertinence and effectiveness of equipment maintenance.Based on the storage and analysis, the production command part provides data sharing service for daily production and emergency dispatching of the electrical department through normalizing information exchange with related management information systems and combining the integrated video monitoring system, and it can improve efficiency of the electrical department daily work.

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Conclusions for the intelligent monitoring technologies

Due to the construction of intelligent Communication & Signalling monitoring maintenance system is a complicated project that can not be achieved overnight and must step-by-step implementation. Meanwhile we need to pay attention to follow issues.(1) We should consider especially the safety hierarchy between devices (equipment) for the device which directly impacts on the railway operation safety should assign a high safety level, The accessory monitoring part should be considered isolated from the control equipment, division of security responsibility explicitly. In addition, the monitoring and maintenance management network should be isolated from the signalling control networks as far as possible and avoid the influence from monitoring network.(2) In the process of implementation specification, we should establish a unified interface protocols and data specification.On this basis, it can realize data sharing of various systems, also can realize module extension and modification according to the need of the system.(3) Pay attention to network security. After the construction of intelligent Communication & Signalling monitoring maintenance system, the relevancy between the maintenance system and control system may be strengthen, therefore, weneed to pay attention to monitoring and maintenance of the management network security, Strictly implementing the safety protecting measures to prevent the invasion of the hackers and virus.

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Thank You for Your Consideratıon

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