Railroad Crossing Control System Research Articles

A proposal of hazard analysis method using structured system theoretical process analysis

System Theoretic Process Analysis (STPA) is a method for analyzing hazards caused by interactions between components of an industrial product. STPA is applied in the upper stream stages of industrial product development, STPA detects hazards while referring to the whole configuration of the industrial product. Therefore, STPA generally does not deal with detailed information about the industrial product. Since the information on the industrial product is insufficient, it is difficult to clarify the factors of hazards, the occurrence order of factors, and the conditions that occur the hazard by STPA. Therefore, the following methods were added to the conventional STPA; the method of describing the components of industrial products in hierarchical detail, the method of clearly defining the behaviour of each component, and the method of tracking the structured CSD to clarify the causes of the hazard. By adding those methods, it became possible to conduct a hazard analysis of the industrial product in detail. As a result of applying the proposed method to the existing railroad crossing control system, it was confirmed that the proposed method could detect more factors of hazards and create adequate scenarios from the occurrence of hazard causes to the occurrence of the hazard.

Sistem Pengaturan Palang Pintu Kereta Api Terintegrasi Sensor Vibrasi, Proximity dan RTC Melalui Komunikasi Wireless

Research has been carried out on an integrated railroad crossing control system proximity sensor, vibration sensor and Real Time Clock (RTC) through wireless communication which can produce a monitoring and control system for railroad crossing gates automatically, knowing the effectiveness of NRF24l01 in providing data wirelessly to inputs that used (proximity sensors, vibration sensors, Real Time Clock), determine the effectiveness of the ATmega 328 microcontroller in processing all input and output data, and determine the work of automatic railroad crossing gates using three inputs (proximity sensors, vibration sensor, and RTC). The method applied in this research is the Research and Development or R&D method. The results of the tests that have been carried out prove that the system has been successfully integrated and effectively works according to the target, namely monitoring and controlling railroad crossing gates with a combination of vibration sensor, proximity sensors and Real Time Clock through wireless communication.

The Research Framework for Quantitative Safety Assessment for Safety-Critical Computer Systems

Objectives: A safety-critical computer system has to be designed with safety in mind. The purpose of this paper is to identify and assess the safety hazards by using the proposed framework for Safety-Critical Computer Systems (SCCS). Methods/Statistical Analysis: Computer software quality models like McCall’s and Boehm’s were deficient in addressing the basic safety issues of SCCS. This paper proposes another safety model for software safety by adjusting McCall’s product quality model that particularly distinguishes the conditions comparing to software safety in safety-critical applications. The conditions in the proposed software safety model relate to Hazard Analysis distinguishing of Completeness of safety requirements, Safety-critical Design, Coding, and Testing. Findings: The criteria in the proposed software safety model relate to Hazard Analysis (HA) distinguishing of safety requirements, Completeness of safety requirements, Safety-critical Design, Safety-critical Coding, and Safety-critical Testing. The proposed safety model changes the current quality model by presenting different safety criteria’s and metrics in all phases of Software life cycle to assess the software safety. This model was connected to a safety basic Railroad Crossing Control System (RCCS) which is a laboratory prototype and obtained better results in terms of safety. Application/Improvements: This model was connected to a safety basic Railroad Crossing Control System (RCCS) which is a laboratory prototype and obtained better results in terms of safety.

The Quantitative Safety Assessment and Evaluation for Safety-Critical Computer Systems

The rapid increase in computer-related technologies puts greater demands on the software-controlled systems. These demands place the software in total control over safety-critical systems. A fault in such a Safety-Critical Computer Systems (SCCS) can result in catastrophic concerns such as loss of life, harm, or equipment damage. In order to detect and prevent such faults, some safety standards, safety analysis and fault-tolerant techniques have been developed. Still, it requires adequate methodologies and frameworks to complete verification of these SCCS. In this work, the software safety is considered into 3 parts: Safety Modeling, Safety Measurement and Safety Management, with assurance lying down to develop high quality software for SCCS. The proposed methodology is SM-Cube (Safety Modeling, Safety Measurement and Safety Management) which is the Safety-Critical Computer Systems concerned. SM-Cube provides a clarified differentiation for assessing and evaluating the safety embedded into the software. SM-Cube consists of required processes and operations for developing SCCS free of faults. This proposed SM-cube has been applied to safety-critical software based Railroad Crossing Control System (RCCS) which is a laboratory prototype. The outcomes of the prototype confirmed that all critical operations have been safe and risk free. The development of the software based on the proposed SM-cube for RCCS have shown a simplified and improved safety-critical operations of the overall system performance

A GQM Based Approach towards the Development of Metrics for Software Safety

Software sometimes safety-critical if it resides in a safety-critical computer systems and it causes or contributes to hazards. Therefore, Safety-critical software intensive systems require verification and validation to confirm that they function as per the safety requirements. Software Safety is a combination of many factors. Metrics are commonly used in engineering as measures for the performance of a system on a given attribute. This paper presents a methodology for software safety framework based on Goal-Question-Metric (GQM) Approach. The proposed methodology was applied to a safety-critical Railroad Crossing Control System (RCCS) which is a laboratory prototype. The outcomes of the prototype are satisfactory and observed that safety risks are within the acceptable threshold level.

Verification of Embedded Real-Time Systems Using Symbolic Model Checking: A Case Study

This p aper presents a case study for symbolic model checking (SMC) with Propositional Projection Temporal Logic (PPTL). First, PPTL is briefly introduced. Then an outline of symbolic model checking algorithm for PPTL proposed in [21] is presented. As a case study, a single-track railroad crossing control system (STRCCS) is employed to illustrate how SMC for PPTL can be utilized in the specification and verification of embedded real-time systems.

A Methodological Framework for Software Safety in Safety Critical Computer Systems

Software safety must deal with the principles of safety management, safety engineering and software engineering for developing safety-critical computer systems, with the target of making the system safe, risk-free and fail-safe in addition to provide a clarified differentaition for assessing and evaluating the risk, with the principles of software risk management. Problem statement: Prevailing software quality models, standards were not subsisting in adequately addressing the software safety issues for real-time safety-critical embedded systems. At present no standard framework does exist addressing the safety management and safety engineering priniciples for the development of software safety in safety-critical computer systems. Approach: In this study we propose a methodological framework involving safety management practices, safety engineering practices and software development life cycle phases for the development of software safety. In this framework we make use of the safety management practices such as planning, defining priniciples, fixing responsibilities, creteria and targets, risk assessment, design for safety, formulating safety requirements and integrating skills and techniques to address safety issues early with a vision for assurance and so on. In this framework we have also analysed integration of applicability of generic industrial heirarchy and software development heirarchy, with derived cyclical review involving safety professionals generating a nodal point for software safety. Results: This framework is applied to safety-critical software based laboratory prototype Railroad Crossing Control System (RCCS) with a limited complexity. The results have shown that all critical operations were safe and risk free. Conclusion: The development of software based on the proposed framework for RCCS have shown a clarified and improved safety-critical operations of the overall system peformance.

Integrated safety analysis of software-controlled critical systems

Software for safety-critical systems must deal with the hazards identified by safety analysis in order to make the system safe, risk-free and fail-safe. Certain faults in critical systems can result in catastrophic consequences such as death, injury or environmental harm. The focus of this paper is an integrated approach to software safety analysis based on a combination of two existing fault removal techniques, and implementation of software safety in developing a small prototype safety-critical system. A comprehensive software safety analysis involving a combination of Failure Modes and Effects Analysis (FMEA) and Fault Tree Analysis (FTA) techniques is conducted on the software functions of the critical system to identify potentially hazardous software faults. A prototype safety-critical system - Railroad Crossing Control System (RCCS), incorporating a microcontroller and software to operate the train on a track circuit is described. We also briefly compare safety-specific and non-safety specific techniques at developing RCCS.

An Approach to Modeling Software Safety in Safety-Critical Systems

Software for safety-critical systems has to deal with the hazards identified by safety analysis in order to make the system safe, risk-free and fail-safe. Software safety is a composite of many factors. Problem statement: Existing software quality models like McCall’s and Boehm’s and ISO 9126 were inadequate in addressing the software safety issues of real time safety-critical embedded systems. At present there does not exist any standard framework that comprehensively addresses the Factors, Criteria and Metrics (FCM) approach of the quality models in respect of software safety. Approach: We proposed a new model for software safety based on the McCall’s software quality model that specifically identifies the criteria corresponding to software safety in safety critical applications. The criteria in the proposed software safety model pertains to system hazard analysis, completeness of requirements, identification of software-related safety-critical requirements, safety-constraints based design, run-time issues management and software safety-critical testing. Results: This model was applied to a prototype safety-critical software-based Railroad Crossing Control System (RCCS). The results showed that all critical operations were safe and risk-free, capable of handling contingency situations. Conclusion: Development of a safety-critical system based on our proposed software safety model significantly enhanced the safe operation of the overall system.

A framework for software safety in safety-critical systems

Software for safety-critical systems must deal with the hazards identified by safety analysis in order to make the system safe, risk-free, and fail-safe. Because human lives may be lost and tremendous economic costs may result if the software fails, the development of high-integrity software adopts practices that impose greater rigor on the software development processes. Software safety is a composite of many factors. Existing software quality models like McCall's and Boehm's and ISO 9126 are inadequate in addressing the software safety issues of real time safety-critical embedded systems. At present there does not exist any standard framework that comprehensively addresses the factors, criteria and metrics (FCM) approach of the quality models in respect of software safety. The safety of a software component must be considered within the context of both the overall system of which it is a component and the environment in which this system operates. It is not useful to investigate the safety of a software component in isolation. This paper proposes a new framework for software safety based on the McCall's software quality model that specifically identifies the criteria corresponding to software safety in safety critical applications. The criteria in the proposed software safety framework pertains to system hazard analysis, completeness of requirements, identification of software-related safety-critical requirements, safety-constraints based design, run-time issues management, and software safety-critical testing. This framework is then applied to a prototype safety-critical system viz. a software--based Railroad Crossing Control System (RCCS) to validate its utility.

Application of Real-Time DEVS to Analysis of Safety-Critical Embedded Control Systems: Railroad Crossing Control Example

This article presents an application of the Discrete Event System Specification (DEVS) framework to the design and safety analysis of a real-time embedded control system, a railroad crossing control system. The authors employ an extension of the DEVS formalism, real-time DEVS (RT-DEVS), which has a sound semantics for the specification of real-time systems in a hierarchical modular fashion. The notion of a clock matrix for communicating RT-DEVS models is proposed, which represents a global time between the models. Based on the composition rules and the clock matrix, an algorithm for the generation of a timed reachability tree is developed that can be used for safety analysis at two phases: an untimed and timed analysis phase. A railroad crossing control example demonstrates that the proposed analysis for RT-DEVS models would be effective to verify the safety property of real-time control systems.