Cab Signaling Research Articles

Investigation of the quality of functioning of a quadrature signals receiver of a continuous automatic cab signaling on records of real signals and interference

Ensuring a safe transportation process is impossible without the use of complex systems for interval regulation of train traffic. In particular, such a system is a continuous automatic cab signaling (CACS) where signals are affected by various kinds of interference, leading to system failures. To reduce the number of system failures, the authors previously proposed a quadrature signal receiver of CACS (QSR of CACS). The article presents the methodology and results of an experimental study of the quality of the functioning of the QSR of CACS on records of real signals and interference. A simulation model of the test facility has been developed in the Simulink simulation environment. The study showed that the QSR of CACS provides reliable reception of CACS code signals with a low level of interference. However, it needs to apply additional measures in it to reduce the influence of impulse noise.

Цифровые технологии пропуска по перегонам и станциям — основа организации движения на Московских центральных диаметрах

train separation, automatic block system, ABTC-MSh system, moving block, interlocking, automatic cab signalling, train control system The article discusses the development of automatic block systems, which form the basis of separation systems. It also highlights the key factors limiting the capacity on open lines, and ways to solve them. A brief overview of the foreign experience of the organization of train separation using automatic block system based on track circuits is given. The article shows the capabilities and role of the computerbased automatic block signalling system with a centralized placement of equipment, audio frequency track circuits and duplicating information transmission channels as an important element of the train traffic management at the sections of Moscow Central Diameters. The significance of the implemented non-stop passage of trains along the main station tracks providing substantial section capacity increase is demonstrated. The necessity of building a digital system for train spacing is shown, which makes it possible to implement the moving block technology with-in the station ensuring the movement of trains on open lines and at stations with the same headway. The advantages of a new type of the computer-based automatic block signalling system as a basic element of a promising Russian train traffic control system and the positive effects of its implementation on the Russian railway network are indicated. The direction of development of train separation systems is outlined within the framework of further digitalization.

ВЛИЯНИЕ ПАРАЗИТНЫХ МАГНИТНЫХ ПОЛЕЙ НА ПРИЕМ КОДА ИЗ РЕЛЬСОВОЙ ЦЕПИ

The paper considers problems connected with transition of useful code signal on receiving locomotive devices. The authors provide data on failures of automatic cab signaling devices on the South-Ural Railway. As a result, they have determined main factors that cause a fault of reception of a useful code and formulated proposals on decrease of influence of sneak fields.

Research on radiated interference from diesel locomotive traction motor to cab signalling

Research on radiated interference from diesel locomotive traction motor to cab signalling

Simulation on adjacent line mutual interference of high-speed railway track circuit

As the density of the high-speed railway network continues to increase, the problem of electromagnetic interference on adjacent lines has become increasingly prominent. This paper focuses on the electromagnetic interference of adjacent lines caused by rail and line in the signal transmission process of the high-speed rail track circuit. Firstly, complete the establishment of the four-terminal network model of the ZPW-2000A track circuit system and the cab signal entry current crosstalk model, calculation of interference voltage under different parallel length of signal frequency. Then the interference factors and coupling mechanism of adjacent lines are analysed to realize calculation of interference amount. Finally, according to the sensitivity index of the cab signal, the maximum parallel length of adjacent sections is given respect, and the interference protection suggestions of adjacent lines are put forward. The research work of this paper provides a theoretical basis for suppressing the interference of adjacent lines and guarantees the safe and efficient operation of high-speed trains.

КОРРЕЛЯЦИОННЫЙ ПРИЕМНИК С КВАДРАТУРНЫМИ КАНАЛАМИ ДЛЯ АВТОМАТИЧЕСКОЙ ЛОКОМОТИВНОЙ СИГНАЛИЗАЦИИ НЕПРЕРЫВНОГО ТИПА АЛСН

Increase of reception validity of continuously working automatic cab signalling (CWACS) signals is still an actual task. One of the possible ways of its solution is to improve existing CWACS receivers of to develop new ones with increased noise immunity. The paper presents a correlation receiver of CWACS signals with quadrature channels. The authors have considered its functional scheme and a simulation model developed in the Simulink environment. Preliminary results gained with the use of the simulation model showed that the receiver is workable. Results of the study can be used at development of new or at improvement of existing microprocessor receivers of CWACS channel.

Оценка влияния электромагнитной обстановки многопутных участков железных дорог на функционирование приемников сигналов автоматической локомотивной сигнализации

Increasing the interference immunity of automatic cab signaling receivers of the main locomotive safety devices using the path-locomotive inductive communication channel is a complex task which, in particular, can be solved by assessing the degree of influence of individual factors leading to equipment malfunctions en route. The present work is devoted to assessing the effect of asymmetry arising under the action of traction current flowing in the rail threads of adjacent tracks on multitrack sections of railways. Based on the Bio - Savard - Laplace law, a system of equations has been compiled to calculate the value of the asymmetry coefficient at the input of the cab receiver. The resulting system takes into account the asymmetry in the rail line of each of the tracks, displacement of the receiving coils relative to the axes and levels of the heads of the corresponding running rails. The analysis showed that in conditions of the receiving coils geometric position asymmetry, the asymmetry at the input of the cab receiver when moving along a multi-track electrified section can be five percent or more. In case of placing test sections of automatic cab signaling check-points on tracks adjacent to tracks intended for passing trains, the asymmetry coefficient at the input of the cab receiver reaches forty percent, which can lead to significant distortions of the results of the tests. The proposed equation system and the results obtained can be used to analyze the electromagnetic situation on multi-track sections of electrified railway lines.

Multi-Valued Automatic Cab Signalling System Based on the CDMA Technology

Purpose. The work is aimed at the development of principles for the construction of multi-valued automatic cab signalling system (ACS) using the wide-band pseudorandom signals. Methodology. An analysis of existing ACS systems and modern telecommunication technologies has been performed to achieve the stated purpose. The multi-valued automatic cab signalling system CDMA-ACS has been proposed. The mentioned system utilizes wide-band pseudo-noise signals to transmit commands. System parameters: frequency band – 155...395 Hz, pseudorandom codes – 16-bit Walsh codes, spectrum spreading factor – 16, source signal bandwidth – 15 Hz, carrier modulation – DBPSK (differential binary phase-shift keying), information rate – 15 bit/sec, code combination length – 4 bits, maximum amount of commands – 256, the duration of single command transmission – 0.27 sec. Functional diagrams of generator and receiver of the multi-valued automatic cab signalling system have been designed. It has been suggested to apply the correlation method to receive the ACS signals. Findings. To investigate the proposed CDMA-ACS system the simulation modelling has been accomplished in MATLAB in two stages: at the first stage, the CDMA-ACS system was investigated as disturbance-free; at the second stage – under the influence of powerful narrow-band disturbances (traction current harmonics). It has been found that the system shows high immunity to narrow-band harmonic disturbances. The most significant harmonics of the traction current related to the system are 250 Hz and 300 Hz, since they are the closest to the carrier frequency of 275 Hz. It has been determined that errors in decoding the ACS commands occur if the signal-to-noise ratio becomes lower than -8 dB. To reduce the influence of 250 Hz and 300 Hz, harmonics the application of additional band-reject filters was proposed. Originality. For the first time, the authors of this work carried out research on the multi-valued automatic cab signalling system with the use of wide-band pseudo-random Walsh codes. Practical value. Implementation of solutions being proposed allows improving the informativeness and interference immunity for the automatic cab signalling system, reducing the duration of command transmission from the railway track to the cab.

Методы приема и синхронизации сигналов автоматической локомотивной сигнализации

The article discusses the problems of existing methods of receiving automatic cab signalling on railway transport, an original method of receiving and processing data is proposed. The need to solve the problems is due to the requirement of a qualitative improvement in the reliability of receiving codes, and as a consequence, the capacity of existing lines. First of all, this refers to a significant increase in the quality of reception and processing of information flows from rail lines. Today it is difficult to imagine the organization of the movement of rolling stock without relying on automatic block systems with secondary sealing of tonal track circuits by frequency modulation signals or automatic cab signaling without the use of multivalued automatic cab signaling with phase-difference modulation. Taking into account the objective fact of noise emission from the operation of energy-intensive railway equipment and modern locomotives, the issues of reliability and noise immunity of receiving discrete information (including signals of traditional automatic cab signaling) are becoming more and more urgent. Analysis of the reasons for the decrease in the reliability and noise immunity of railway automation and telemechanics systems, and, consequently, traffic safety also comes to the fore.

Main electromagnetic jammer sources with impact on the railroad automation systems

The article presents some results of research to improve the stability of rail circuits and automatic cab signaling on the Railways. Signals of automatic locomotive signaling under the influence of stationary harmonic and random impulse noise are considered, the sources of which can be power lines, power devices, radio frequency electromagnetic fields, electrostatic discharges, lightning discharges, traction power supply and rail networks, as well as adjacent rail circuits. Particular attention is paid to the negative effects of reverse traction current and the uneven magnetization of the rails. It is shown that the practical implementation and application of the developed methods to increase the reliability of automatic locomotive signaling systems should suppress powerful interference from reverse traction currents that occur on locomotive receiving coils during heavy train traffic. Also, this should provide suppression of interference from the uneven magnetic field of the rails laid in the path or in the rut and at the ends of the sleepers. This will lead to a decrease in the intensity of failures in the operation of automatic locomotive signaling and to an increase in the level of safety and uninterrupted movement of trains. The results are successfully used on the railways of Russia and abroad.

Quantitative analysis on coupling of traction current into cab signaling in electrified railways

Cab signaling apparatus is the critical equipment for ground-vehicle communication in electrified railways. With the rapid development of high-speed and heavy-haul railways, the immunity to unbalanced traction current interference for cab signaling apparatus in the onboard train control system is increasingly demanded. This paper analyzes the interference coupling mechanism of the ZPW-2000 track circuit. Based on electromagnetic field theory and the actual working parameters, a calculation model is established to complete the quantitative research of the cab signal induction process and traction current interference. Then, a finite element model is built to simulate the process. The simulation results under the signal frequency, fundamental and harmonic interference are all consistent with the theoretical calculation results. The practical measurement data verify the coupling relationship between cab signal inductive voltage and rail current. Finally, an indirect immunity test method applying this relation for the cab signals is proposed, and the voltage indexes of the disturbance sources are determined, i.e., the test limits. The results provide an accurate quantitative basis for the cab signaling research and design of the immunity test platform; besides, the proposed indirect test method can simplify the test configuration and improve test efficiency.

Optimization method of switch jumper setting based on strategies for reducing conductive interference in railway

Traction current can to impose conductive interference on the railway signalling system, which is also known as unbalanced traction current interference. In the station turnout section, the traction current may cause obvious interference on both receiving apparatus of track circuit and cab signalling apparatus due to the installation of multi-jumpers, wing rails, and insulated joints inside the turnout. This paper analyzes the above structural characteristics of turnouts in depth. By establishing a comprehensive simulation model of one-transmitter and two-receiver track circuit in turnout section and simulating the complete return current path along with traction network–locomotive–rails, the mechanism of traction current conductive interference in the turnout section is then illustrated, using Multisim and MATLAB/Simulink simulation platform. Finally, based on the Analytic Hierarchy Process (AHP), an optimization method of switch jumper setting is studied. The simulation results show that the conductive interference in the turnout section mainly involves two factors: The inherent turnout structure definitely results in different impedance of two rails, and the inductive cab signal is partly bypassed in the turnout center (nose rail). Especially, conductive interference magnitude depends on the jumper location. Therefore, in engineering practice, it is feasible to reduce the interference to a certain degree by reasonable settings of the switch jumper.

Методика определения порогового значения отношения сигнал/помеха для систем автоматической локомотивной сигнализации

Методика определения порогового значения отношения сигнал/помеха для систем автоматической локомотивной сигнализации

Concerning the Carrier Frequency Selection Method for Continuous Cab Signaling

This paper considers the carrier frequency selection method for continuous cab signaling using a set of criteria for minimum inductive-rail line attenuation and maximum noise immunity. The mathematical expressions used for evaluation of signal attenuation in rail, inductive, and inductive-rail lines are given, and the corresponding conditions and assumptions are indicated. To determine the locomotive receiver noise immunity, the method of simulating its operation was used when receiving an additive mixture of an amplitude-shift keyed signal and impulse noise. It is shown that, under the indicated conditions and criteria, the optimal frequency values are 325 and 375 Hz.

УЗКОПОЛОСНЫЙ ЦИФРОВОЙ ФИЛЬТР ДЛЯ ВЫДЕЛЕНИЯ СИГНАЛОВ АЛСН В УСЛОВИЯХ ДЕЙСТВИЯ ИНТЕНСИВНЫХ ПОМЕХ

УЗКОПОЛОСНЫЙ ЦИФРОВОЙ ФИЛЬТР ДЛЯ ВЫДЕЛЕНИЯ СИГНАЛОВ АЛСН В УСЛОВИЯХ ДЕЙСТВИЯ ИНТЕНСИВНЫХ ПОМЕХ

Особенности системы управления движением поездов на высокоскоростной магистрали «Москва–Казань–Екатеринбург»

Objective: To consider the requirements for the train control system (SUDP) at “Moscow-Kazan-Yekaterinburg” high-speed network (VSM). To develop system-wide requirements for SUDP, including the selection of the structure and composition of subsystems. Methods: Computer-based interlocking with contactless control of vehicles should be applied at the stations as the main means for train traffic control. Vocal frequency track circuits were determined as the major means for free and busy status control of track at stations and blocks, an information channel giving an update of a track ahead, and the means for a rail integrity test. Stationary equipment for train collision avoidance via radio channel is to provide train traffic with speeds up to 400 km/h, multiple-aspect ALS-YEN (integrated continuous automatic cab signaling system), depending on control technology with speeds up to 250 km/h and ALS (automatic locomotive signaling system) – up to 160 km/h. Results: The issues of providing reliable and safe functioning of SUDP were considered, as well as liveness and interoperability. Practical importance: Control system realization in the suggested configuration with combined data communication via radio channel and conventional ALS and ALS-YEN facilities will make it possible to provide train traffic collision avoidance backup, as well as interoperability with high-speed transport lines. Keywords: High-speed network, train control system, centralized traffic control, computer- based interlocking, train traffic collision avoidance, radio-block center.

Adaptive noise abatement in automatic cab signaling receivers

Under conditions of a priori noise uncertainty, it is effective to use adaptive noise-abatement techniques to improve noise protection of continuous automatic cab signaling (CACS) receivers. The purpose of this article is to study the possibilities of an adaptive signal-processing technique, adaptive noise filtration (AF), providing better noise resistance of the CACS signals. To achieve this goal, the following problems are solved: a mathematical model of the CACS receivers' input signals is developed, a functional circuit and adaptation algorithm of a basic and a modified multichannel CACS receivers' adaptive filters is substantiated, and a computer simulation of adaptive filters is performed, confirming the accuracy of the obtained results and effectiveness of such filters for noise reduction. A distinctive feature of the proposed filters, which significantly expands their functionality, is a priori information on the presence of breaks in the CACS signals used in the adaptive algorithms.

USE OF AUTOMATIC SIGNALLING SYSTEM FOR REDUCTION OF THE RISK OF TRANSPORTATION INCIDENTS IN RAILWAY STATIONS

Aim. Evaluating the risk of collision between trains during shunting operations in railway stations. Risk is the combination of the probability and consequences of an event. The most complicated task related to risk assessment is the choice of the evaluation model for the probability of an undesired event. The model must ensure practical applicability of the results. In the context of railway facilities the construction of analytical models of probability evaluation is of principal interest due to the possibility to demonstrate the factors that are taken into consideration by the model. The main purpose of this paper is to examine the extent to which the Shunting Automatic Cab Signalling System (MALS) contributes to the probability of side collision of trains involving shunting engines in railway stations. The main function of the Shunting Automatic Cab Signalling System is to ensure that shunting engines do not pass signals at danger in stations. Methods. Methods of the probability theory and theory of random processes, addition, multiplication formulas, composite probability, properties of Poisson flows. In [2] a method is suggested for calculating the probability of collision as the result of shunting or train locomotive passing a signal at danger. The development of the method was based on the main assumption that the flow of shunting consists for each switch is a Poisson flow. This paper suggests a modification of this method that takes into consideration the possible use of the MALS system with shunting engines. The input data for the algorithm of calculation of the collision probability are the station topology, passenger train schedule and their possible routes through the station, average train lengths and speeds, as well as the frequency of shunting consists passing over switches. Results. An algorithm has been developed for calculation of the probability of train-to-train collision involving shunting engines within a random time period. For different operating modes, e.g. pulling up, coupling, formulas are shown for calculation of the probability of collision with a passenger or freight train on a random switch. The algorithms consists in the following: 1) a time period is specified for which it is required to calculate the probability of collision; 2) passenger train timetable is designed using data from ASU “Express”; 3) overall number of passenger trains passing through the station within the specified time period is calculated; 4) passenger trains are renumbered according to the order of their arrival to the station; 5) probability of signal violation by shunting engine driver is calculated; 6) probability of violation of traffic safety by shunting engine driver in the “pull up” mode is calculated; 7) probability of violation of traffic safety by the shunting engine driver after coupling with the “coupling” mode off is calculated; 8) overall number of possible routes for each train is calculated; 9) for each train the frequency of one or another route is identified; 10) for each switch of each route a number is specified in the order of appearance; 11) probability that each passenger train on each route has at least one collision is calculated; 12) probability of at least one collision of each passenger train moving through the station is calculated; 13) probability of at least one collision in the station within the specified period of time is calculated. The paper considers the example of calculation of collision probability for an individual train route and the station as a whole within a month and a year. It shows that the use of MALS helps significantly reduce the probability of side collisions in railway stations.

Alternating traction current dynamics in track lines of double-track hauls

The operational stability of track circuits and continuous cab signaling in electrified railway sections is disturbed most often by traction current noises in the track line. They are generated when asymmetrical traction current is produced at the points where track circuit equipment is connected to the tracks or under sending cab coils of continuous cab signaling. From the standpoint of traction current flows, a single-track haul track line can be considered a solitary double-wire circuit with two reciprocally induced singlewire electric circuits. As a result, traction current asymmetry becomes easier to calculate. In the case of double-track hauls, this problem is much more difficult to solve, because the traction network in these hauls additionally includes electrified trackways of adjacent tracks, second contact wire, and longitudinal power supply lines laid on catenary supports. These lines are reciprocally inductive with the considered trackways. The considered hauls are characterized by different distances from each trackway to additional electric lines, for which reason the reciprocal inductances inversely related to these distances are different as well. According to the analysis of the proposed procedure of calculating the traction current asymmetry in the track line, this asymmetry depends not only on electric resistances and specific reciprocal inductances of interlinked singlewire electric power lines, but also on the ratio of currents in these lines. It has been established that the absolute value of traction current asymmetry at a particular point of the track lines is indicated more adequately by the level of impact of traction current asymmetry on the operational stability of track circuits than by the traction current asymmetry factor. The time course of the traction current asymmetry in the track line depends on variations in the ambient temperature, traction current in the rails, and electric resistances in the junctions of parts of track bonds, choke jumpers, and ground circuits of catenary line supports. Additional changes in the traction current asymmetry under sending cab coils occur during train traffic and depend on the inbound resistances of track line sections ahead, as well as on any uneven longitudinal track magnetization.

IMPROVING THE POSITIONING ACCURACY OF TRAIN ON THE APPROACH SECTION TO THE RAILWAY CROSSING

Purpose. In the paper it is necessary to analyze possibility of improving the positioning accuracy of train on the approach section to crossing for traffic safety control at railway crossings. Methodology. Researches were performed using developed mathematical model, describing dependence of the input impedance of the coded and audio frequency track circuits on a train coordinate at various values of ballast isolation resistances and for all usable frequencies. Findings. The paper presents the developed mathematical model, describing dependence of the input impedance of the coded and audio-frequency track circuits on the train coordinate at various values of ballast isolation resistances and for all frequencies used in track circuits. The relative error determination of train coordinate by input impedance caused by variation of the ballast isolation resistance for the coded track circuits was investigated. The values of relative error determination of train coordinate can achieve up to 40-50 % and these facts do not allow using this method directly for coded track circuits. For short audio frequency track circuits on frequencies of continuous cab signaling (25, 50 Hz) the relative error does not exceed acceptable values, this allow using the examined method for determination of train location on the approach section to railway crossing. Originality. The developed mathematical model allowed determination of the error dependence of train coordinate by using input impedance of the track circuit for coded and audio-frequency track circuits at various frequencies of the signal current and at different ballast isolation resistances. Practical value. The authors proposethe method for train location determination on approach section to the crossing, equipped with audio-frequency track circuits, which is a combination of discrete and continuous monitoring of the train location.