Chinese Train Control System Level Research Articles

Reliability Analysis of CTCS-3 Train-Ground Communication System Based on 5G-R

The reliability of Chinese Train Control System Level 3 (CTCS-3) train-ground communication system is of great importance to ensure the safe operation of trains. The fifth Generation Mobile Communication for Railway (5G-R) is prospective for train-ground communication in the future. In this paper, the train-ground communication procedure of 5G-R (e.g., connection reestablishment, handover and train-ground data transmission) is tested by a semi-physical simulation platform. The test results, including the delay of different procedures together with the handover success rate, all can satisfy the quality of service (QoS) requirements. According to the communication procedure, deterministic and stochastic Petri net (DSPN) models of communication links and train-ground communication scenarios are established. Furthermore, the parameters of models are calibrated with the test data and protocol standards. We utilize <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$\pi$</tex-math></inline-formula> -tool to simulate and analyze the reliability of the train-ground communication system under the interaction of multiple fault factors. The results show that even in the worst handover scenario where the station distance is 1 km and the train speed is 400 km/h, the reliability of the train-ground communication system based on 5G-R can still reach 99.9963 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$\%$</tex-math></inline-formula> . It not only meets the requirements of the train control services for the train-ground communication system, but also is better than the reliability of the GSM-R based communication system.

Feasibility Analysis of GSM-R System for Railways in Indonesia: Case Study of Jakarta Bandung High Speed Train

High-speed railway technology development necessitates the development of a communication system that supports various components of train operation facilities, such as train control, safety communication, and others. The construction of fhigh-speed railway in Indonesia in the Jakarta-Bandung area uses the Chinese Train Control System (CTCS) Level 3 signaling system, which makes the Global System for Mobile Communication-Railway (GSM-R) a wireless signaling network system. Because there are already existing GSM-based public telecommunications services, known as public GSM, on the same frequency used by a number of cellular operators in Indonesia, the use of GSM-R poses implementation challenges. This will result in reduced service quality and revenue for protected cellular network operators due to the use of these frequency bands to support the operation of high-speed railway services in Indonesia. In this study, an evaluation was carried out to look for other potentials from using the GSM 900 MHz frequency band, which can be used as an option to be implemented on high-speed trains in Indonesia. The research begins with calculating the estimated potential loss of revenue from using telecommunications network operators. This data will be analyzed in terms of the economic feasibility of several other frequency band choices for implementing the GSM 900 MHz frequency band on high-speed trains in Indonesia, so that it is hoped that this will become a new consideration that can become a solution and recommendation in the application and use of GSM-R technology in Indonesia.

Feasibility Analysis Of Gsm-R System For Railways In Indonesia: Case Study Of Jakarta Bandung High Speed Train

High-speed railway technology development necessitates the development of a communication system that supports various components of train operation facilities, such as train control, safety communication, and others. The construction of fhigh-speed railway in Indonesia in the Jakarta-Bandung area uses the Chinese Train Control System (CTCS) Level 3 signaling system, which makes the Global System for Mobile Communication-Railway (GSM-R) a wireless signaling network system. Because there are already existing GSM-based public telecommunications services, known as public GSM, on the same frequency used by a number of cellular operators in Indonesia, the use of GSM-R poses implementation challenges. This will result in reduced service quality and revenue for protected cellular network operators due to the use of these frequency bands to support the operation of high-speed railway services in Indonesia. In this study, an evaluation was carried out to look for other potentials from using the GSM 900 MHz frequency band, which can be used as an option to be implemented on high-speed trains in Indonesia. The research begins with calculating the estimated potential loss of revenue from using telecommunications network operators. This data will be analyzed in terms of the economic feasibility of several other frequency band choices for implementing the GSM 900 MHz frequency band on high-speed trains in Indonesia, so that it is hoped that this will become a new consideration that can become a solution and recommendation in the application and use of GSM-R technology in Indonesia.

The Search-Based Mutation Testing of the Chinese Train Control System Level 3 On Board a Train Control System

In this article, we combined a search-based technique with model-based mutation testing to overcome the inherent computational cost that comes with the test-case generation of the Chinese Train Control System Level 3 (CTCS-3) train control system by providing a newly designed fitness function to guide the search process of test cases. First, we defined the test-case inputs as <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">timed input traces</i> , which can easily deal with noninput-enabled systems with both input events and input variables. Because the input sequence of the timed input traces can be potentially infinite, they can be more flexible in dealing with different scales of train control systems than can the traditional model-checking techniques. Furthermore, we proposed a way of encoding timed input traces as blocks of inputs for the genetic algorithm, together with crossover and mutation operators, to reduce the search space and improve algorithm efficiency. By using the encoded input blocks as individuals, the test cases generated from the train control system will be more compact and easier to perform. Finally, we applied the mutation operators to the mode-transition function of the CTCS-3 from which all of the known faults have been considered comprehensively. To evaluate the coverage of the test cases generated and compare the performance of different methods, the benchmarking indicators of conformance relation score (CRS), average CRS, and weighted CRS have all been analyzed. In addition, we performed an experiment to determine the extent to which the maximum block width can influence the search performance as a guidance for parameter selection in practice.

Crucial States Estimation in Radio Block Center Handover Using Petri Nets With Unobservable Transitions

The radio block center (RBC) is one of the most essential ground systems in a high-speed train control system both in Europe and in China. The RBC handover procedure is an important function of RBC, which affects the transport efficiency, reliability and safety of railways. Analysis of crucial states in the RBC handover procedure is helpful to determine whether there are potential risks in the procedure, and to locate the fault in time when a fault occurs. In this paper, we study a property, called C-detectability, of the RBC handover. This property has been defined in discrete event systems and requires that the crucial states can be determined uniquely by observing the system output. Taking the RBC handover procedure in the Chinese train control system level 3 (CTCS-3) as an example, we first model the RBC handover procedure using Petri nets, which are a graphical and mathematical modeling tool to formalize the behavior of discrete event systems. Then, based on the notion of basis reachability graph, an efficient approach is used to check C-detectability of the Petri net modeling the handover procedure. <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">Note to Practitioners</i> —The railway system is a safety-critical system. System safety is essential to the railway system. It is necessary to provide formal methods to model the system and analyze its properties. The motivation of this work is to present a general modeling framework of railway systems for the crucial states estimation. The crucial states estimation of the railway system has not been discussed yet in the literature despite its importance due to its relationship with the safety of the railway. In particular, estimating the crucial states in the railway system helps to determine whether there are potential risks in the system. In this paper, we investigate a new state estimation property (C-detectability), which is related to fault diagnosis, marking estimation and fault identification. Future research will consider the use of timed Petri nets to increase the modeling power and to allow the performance analysis of the railway system.

Evaluating operational risk for train control system using a revised risk matrix and FD-FAHP-Cloud model: A case in China

An accident caused by train control system may not only bring expensive loss, but also result in severe destruction to surrounding environment. The purpose of this study is to study operational risk of Chinese Train Control System- Level 3 (CTCS-3). An integrated risk assessment method is developed by combining fishbone diagram (FD), Fuzzy Analytic Hierarchy Process (FAHP) with cloud model. Based on fishbone diagram, risk factors (RFs) of train control system are identified from two perspectives of hazard event, namely occurrence frequency and sequence severity. To further classify RFs quantitatively, a revised risk matrix based on FAHP is introduced to calculate the consequence and likelihood weights for each risk factor (RF), and then Risk Index (RI) is getting by making product of consequence and likelihood weights, which reflects relative influence degree on operational risk. Finally, in order to assess the comprehensive operational risk of CTCS, cloud model is used to logically calculate quantitative results, and the CTCS-3 in Wuhan-Guangzhou high-speed railway is empirically investigated to analyze its overall operational risk level. The result shows that its risk level is between medium and low, and more inclined to low, which means being acceptable but not ideal. Meanwhile, some specific suggestions and measures are proposed to eliminate or reduce RFs with higher frequency and worse consequence.

Reliability analysis on the train control system in the CTCS-3 operating mode

Purpose This paper aims to study the reliability of the high-speed train operation control system in the Chinese Train Control System Level 3 (CTCS-3) operating mode. Design/methodology/approach Dynamic fault tree and Bayesian network method are adopted to analyze the reliability and weakness of the CTCS-3 system. Findings First, a physical architecture and data flow diagram of the CTCS-3 system are established according to the typical structure and functions of the CTCS-3 system. Second, the dynamic fault tree of the CTCS-3 system is constructed. Considering the prior probability of the bottom event and the existence of dynamic redundancy, the dynamic fault tree is transformed into a Bayesian net. The reliability of the CTCS-3 system is carried out based on the prior probability and the weakness that affects the reliability of the system based on the posterior probability is also analyzed by the Bayesian network. Finally, it is disclosed that the impact of the on-board subsystem on the reliability of the CTCS-3 system is generally greater than that of the ground subsystem. The two weakest modules in the onboard subsystem are the driver-machine interface (DMI) and balise transmission module (BTM) and the weakest one in the ground subsystem is Balise. The analysis results are generally consistent with the malfunctions in the field operation of China’s high-speed railway. Originality/value (1) By reasoning, the reliability of the train operation control system in the CTCS-3 operating mode meets the standard requirements. (2) Through backward reasoning, it is found that the failure of the onboard subsystem leads to a greater probability of failure of the train control system. (3) The DMI, BTM and automatic train protection computer unit modules are weak components in the onboard subsystem. Vital digit input&amp;output, train interface unit and train security gateway are rarely involved in previous research, the result in this paper shows that these three modules are also weak components in the subsystem, which requires attention.

Sustainable Fault Diagnosis of Imbalanced Text Mining for CTCS-3 Data Preprocessing

At present, the method for fault diagnosis and maintenance of the CTCS-3 (Chinese Train Control System Level 3) electronic equipment relies too heavily on expert knowledge. Moreover, the use of historical fault data is not valued. This paper proposes a sustainable fault diagnosis model based on imbalanced text mining. First, to process fault data from the field recorded in natural language, natural language processing technology is used to extract fault feature words. Then, a term frequency-inverse document frequency model is used to transform the fault feature words extracted from the database into vectors. It is worth noting that imbalance in the fault samples affects the accuracy of this sustainable fault diagnosis model. To solve this problem, we use the borderline-synthetic minority over-sampling technique in the step of predicting train fault components, we also use the backpropagation neural network we proposed and the naive Bayesian model which is commonly used as a classification model, to compare the prediction accuracy of these two algorithms. The experimental results perform well, which proves that the fault diagnosis method using the backpropagation neural network can further assist engineers to complete timely repair and maintenance work. The research in this paper has played a very important role in technical support for intelligent train dispatching and command, and will also play a positive role in technical support for the automatic operation of urban rail transit under the prevention and control of the new coronavirus.

Non-Deterministic Delay Behavior Testing of Chinese Train Control System Using UPPAAL-TRON

The Chinese Train Control System level 3 (CTCS-3) is an open and real-time safety-critical system. Due to the non-deterministic delay behavior in the environment, there is a large number of stimuli to the train control system with different patterns of arrival times. Control strategies must be well considered, as either the logic of the function fails or the real-time constraints are dissatisfied, may directly lead to significant human injury or financial loss. In this paper, we introduce the notion of test specification and the relativized timed input/output conformance based on timed automata theory. A new test case generation and execution algorithm has been proposed, by which the tester can reset Implementation Under Test (IUT) whenever they want, make it more sense in specific domain fields. We apply UPPAAL-TRON based online conformance testing framework to test nondeterministic delay behavior of Radio Block Center (RBC) handover scenario of CTCS-3 against critical safety, real-time, and liveness properties (defined in the system requirement specification (SRS) documents). Our experiments show that assurance of collision avoidance and train non-derailment can be guaranteed, but emergency brake intervention may happen with low probability in this scenario under the requirements specified in the SRS document.

Towards A Test Paths Generation Method for CTCS Level Transition

Test case is an important basis for correctness and safety verification of Chinese Train Control System (CTCS). Focusing on the test cases generation method of UPPAAL which is widely used in CTCS testing activity, the problems are analyzed, and an improved test cases generation method for CTCS is proposed. First, the process and characteristics of UPPAAL test cases generation method are analyzed; then the test requirements of CTCS are studied, and a test cases generation method based on UPPAAL query file is proposed. Finally, taking the level transition function of CTCS as an example, test cases are generated by the proposed method, which shows that this method can meet the test requirements of CTCS.

Reliability evaluation of the Chinese Train Control System Level 3 using a fuzzy approach

The Chinese Train Control System Level 3 (CTCS-3) has been developed to ensure the safe and efficient operation of high-speed railway networks in China. Failure of the CTCS-3 may result in serious accidents, causing damage to assets and risking the safety of passengers. In this paper, the reliability evaluation of the CTCS-3, comprising an onboard and trackside subsystem, is conducted using the fault tree analysis where the basic events are divided into known failure rate basic events and unknown failure rate basic events. The probabilities of the occurrence of the known basic events are obtained from field data, while those of the unknown failure rate basic events are estimated by expert judgment. The fuzzy set theory is then adopted to deal with the imprecise expert judgment. Considering a specific operational scenario, to accomplish one mission, the failure probability of the CTCS-3 is calculated. Importance analysis is carried out not only to identify the critical basic events but also to provide suggestions on the improvement of preventive maintenance. Sensitivity analysis shows that hardware factors have the most significant effect on the reliability of the CTCS-3.

Quantitative Performance Evaluation of Uncertainty-Aware Hybrid AADL Designs Using Statistical Model Checking

The hybrid architecture analysis and design language (AADL) has been proposed to model the interactions between embedded control systems and continuous physical environment. However, the worst-case performance analysis of hybrid AADL designs often leads to overly pessimistic estimations, and is not suitable for accurate reasoning about overall system performance, in particular when the system closely interacts with an uncertain external environment. To address this challenge, this paper proposes a statistical model checking-based framework that can perform quantitative evaluation of uncertainty-aware hybrid AADL designs against various performance queries. Our approach extends hybrid AADL to support the modeling of environment uncertainties. Furthermore, we propose a set of transformation rules that can automatically translate AADL designs together with designers’ requirements into networks of priced timed automata and performance queries, respectively. Comprehensive experimental results on the movement authority scenario of Chinese train control system level 3 demonstrate the effectiveness of our approach.

An extended system-theoretic hazard analysis method for the safety of high-speed railway train control systems

A high-speed railway train control system plays a key role in ensuring the safe operation of the trains. To ensure the safety of high-speed railway train control systems, it is vital to perform hazard analysis on them. In this context, this paper proposes a novel hazard analysis method which extends a previously reported system-theoretic hazard analysis method “system-theoretic process analysis.” The proposed method improves the standard system-theoretic process analysis to capture the temporal relations between inadequate control actions leading to hazards. These temporal relations are crucial for investigating the causes of hazards. To depict the temporal relations of control actions of high-speed railway train control systems, a new temporal logic called “control action temporal logic” is proposed first. Then based on this temporal logic, a new control action relation model is added into the process of system-theoretic process analysis. This model depicts the relations (including temporal relations) between control actions. In order to identify both the inadequate control actions and their temporal relations, an algorithm is designed and used. Finally, the effectiveness of the proposed method is verified through the hazard analysis on the Chinese Train Control System level 3.

An integrated hazard identification method based on the hierarchical Colored Petri Net

The traditional hazard analysis approaches applied to the socio-technical system cannot cover the complex organization structures, the interactions between systems and human behaviors, the interrelated factors among sub-systems and the safety culture of specific societies. This paper presents an integrated hazard identification approach named System-Theoretic Process Analysis Based on Formalization Model (BFM-STPA), which can solve the above issues. Firstly, the hierarchical control structure models of the socio-technical system are established through Colored Petri Nets (CPN) due to its strong description ability and executable ability, which may also be regarded as the graphical system specification. Secondly, the hazards can be identified according to the CPN models following a series of guide conditions. Thirdly, the comprehensive contributing factors to the hazards will be found out by tracing the former states within the reachability graph generated from CPN model. Finally, an integrated hazard log can be derived for further hazard analysis and safety-guided design. In this paper, the above method was applied in the Chinese Train Control System level 3 (CTCS-3). And the process of hazard identification for the scenario of Temporary Speed Restriction issued was elaborated in detail. Compared with the hazard log generated by Hazard and Operability (HAZOP), the hazard log generated by BFM-STPA covered not only the subsystem failures, but also the deviation of interactions among subsystems from design intent, human errors and socio-technical drawbacks related to the TSR Issued scenario of CTCS-3.

Model-Based Test Case Generation for Function Testing of CTCS-3 Onboard Subsystem

The CTCS-3(Chinese Train Control System level 3) is an automatic system which is an integrated of advanced control technology, advanced communication technology, advanced computer technology and railway signal technology. It plays an important role in assuring safety and improving efficiency in railway. As a core subsystem in CTCS-3, the onboard subsystem is a typical safety-critical system, in which any fault can lead to huge human injury or wealth losing. Function testing method which is mainly focus on the conformance relation between the specification and the System Under Test (SUT) has been widely used in testing onboard subsystem in the past few years. However, most of the test cases are manually generated which can’t be reused and leads to repeated works when the specification is changed. To improve the testing efficiency and quality, model-based testing method is introduced. We use a tool chain to generate test case automatically based on Timed Automata theory and then apply in function testing of onboard subsystem. Firstly, we establish the scenario-tree by analyzing the specification of onboard subsystem and Vital Computer and Environment (V-E) timed automata network model of mode transition using tool Uppaal. Then, according to the relation between train modes and operational scenarios, test cases are automatically generated by tool CoVer with definition coverage criteria based on the Observer Automata theory. Finally, a selection algorithm is given to choose a complete test sequence from the test cases. Different test suitss of onboard subsystem are acquired and compared with different coverage criteria and coverage items. A complete model transition function test suits are derived which is proven very useful for testing the onboard subsystem.

Behavior modeling and verification of movement authority scenario of Chinese Train Control System using AADL

Train control systems like most digital controllers are, by definition, hybrid systems as they interact with or try to control some aspects of the physical world. Detailed behavior modeling with constraints specifica-tion and formal verification, required for reliability prediction, is a great challenge for hybrid system designers. Train control systems further intensify this challenge with extensive interaction between computing units and their physical environment and their mutual dependence on each other. In this paper, we investigate behavior modeling and formal verification of Chinese Train Control System Level 3 (CTCS-3) using Architectural Anal-ysis & Design Language (AADL) to cope with this challenge. AADL is an architecture description language for embedded systems and is based on model-based engineering paradigm. Along with structural modeling of em-bedded systems using the core language constructs, AADL also provides support for language extension through annex sublanguages. In system requirements specification document, the behavior of the CTCS-3 is specified as a set of basic operation scenarios that cooperate with each other to achieve safe and secure functionality of trains. Movement Authority (MA) scenario, explored in this paper, is considered as a basic and most crucial scenario to prevent trains from colliding with each other. The detailed discrete behavior of control system is modeled and verified using the Behavior Language for Embedded Systems with Software (BLESS) annex sublanguage of AADL, and the continuous behavior of train with the cyber-physical interaction (communication between train and control system) is modeled using the Hybrid annex sublanguage. The behavior of the MA scenario at system level is verified using the Hybrid Hoare Logic theorem prover. Behavior constraints are specified as assertions using first-order logic formulas augmented with a simple temporal operator.

HAZOP Study on the CTCS-3 Onboard System

The safe operation of Chinese Train Control System Level 3 (CTCS-3) is of great significance, particularly with respect to the increasing operational speed and expanding railway networks of the Chinese high-speed railway system, which has drawn deep concern from both customers and strategic makers. A hazard and operability (HAZOP) study has been recognized as an effective systematic examination to identify any potential problems existing in various industrial processes or operations. This paper presents a process of applying a HAZOP study to identify the hazards of a CTCS-3 onboard system for the first time, which is composed of two major parts: system models and hazard identification on the examination session. To better reflect the structure and functions of a CTCS-3 onboard system, the following models are developed, i.e., a reference model, a function hierarchical model, a state diagram, and a sequence diagram. To demonstrate the effectiveness of the HAZOP study, hazard identification on the basis of the functions of the CTCS-3 onboard system and a scenario of temporary speed restriction is considered and employed. The results indicate that existing hazards can be dug out at express speed, which allows the relevant actions to be proposed and implemented to prevent the hazards from spreading to a wide range in the whole CTCS-3 onboard system.

Automated Test Approach Based on All Paths Covered Optimal Algorithm and Sequence Priority Selected Algorithm

A timely and complete test is an important factor to assure the functionality and safety of a railway signal system before it is put into service. With the development of rail transportation in China, the traditional semiautomatic test methods cannot satisfy the timely and complete test requirements any longer. This paper proposes an automated model-based test method. First, colored Petri nets are used as a formal language to describe the system specification. Second, the all paths covered optimal algorithm and the sequence priority selected algorithm are proposed to generate the test cases and sequences automatically. Third, taking a typical radio block center (RBC) handover scenario as an example, the generated test cases and sequences are applied into the RBC functionality test platform. The testing result validated the feasibility and efficiency of the proposed automated test method. Compared with the random-walk-based test sequence generation algorithm, the repeatability rate of the generated test sequences is reduced by 46%. The test sequences can cover all the generated test cases, and the cases can cover all the related criteria in the function requirements specification of the Chinese Train Control System Level 3.

Modeling and Verification of RBC Handover Protocol

Radio Block Center (RBC) is a core part of the Chinese Train Control System level 3 (CTCS-3) which is a protocol for safety critical systems. The correctness of the RBC handover protocol is one of the most important factors affecting the safety of systems. Hence, it is of great importance to ensure the correctness of the protocol. To this end, some formal methods have been used to model and verify the protocol. In this paper, we use Modeling, Simulation and Verification Language (MSVL) as the formal language to model and verify the protocol. The result shows that the behavior of RBC handover is consistent with the specification.

Enhanced robustness of control network for Chinese Train Control System Level-3 (CTCS-3) facilitated by software-defined networking architecture

In order to provide high reliability for train control networks, ring redundant network configuration has been widely deployed in Chinese Train Control System Level-3. In this paper, we propose a centralized ring redundant link failure failover management scheme that is based on a software-defined networking architecture, where OpenFlow protocols and a POX controller are adopted. Contrary to the traditional ring redundant schemes that flush all the forwarding information databases when failover proceeds, the proposed scheme simply updates the forwarding information needed to be changed according to the global topology and is link-flapping-free. Simulation and experiment results demonstrate that the proposed scheme is superior to the Media Redundancy Protocol in terms of the obtained system recovery time, the bandwidth, the time delay and the packet loss when failover proceeds.