Mustafa Seckin Durmus

Fail-Safe Signalization Design for a Railway Yard: A Level Crossing Case

Abstract Level crossings (grade crossings or railroad crossings) are one of the most crucial parts of the railway lines as two different types of transportation intersect at these points. Human failures including ignorance of warning signs, device troubles or carelessness can easily result in accidents especially at such cross-sections. In order to decrease the possibility of accidents on level crossings, several standards have been developed. In accordance with these standards, formal methods are required to be used specially in the development of interlocking systems that control safe operation of such crossings. In this study, a railway yard with a level crossing is modeled by Automation Petri Nets in order to design a failsafe signalization system. A SCADA testbed is also developed to test several possible failure situations. The methods proposed in the design are expected to be used as part of an interlocking system in a railway station in Turkey.

The Application of Automation Theory to Railway Signalization Systems: The Case of Turkish National Railway Signalization Project

Abstract The application of control and automation theory to practical areas can provide significant means for improvement in developing countries like Turkey, where human (brain) power is relatively inexpensive. A possible application area for the well established automation theory is railway signalization, where formal methods are required to be used in order to comply with the related safety standards. Turkish National Railway Signalization Project (TNRSP) is examined in this paper with this perspective as a case study. Development stages, architecture and design of the software produced in this project are briefly discussed.

Interlocking system design for ERTMS/ETCS: An approach with batches Petri nets.

Abstract In order to optimize and to standardize the train traffic across Europe, railway people developed new standards known as European Rail Traffic Management System (ERTMS) that has three levels from conventional rails (level 1) to high speed rails (level 3). The use of this standard is not limited only in Europe and became a widely used standard in Asia and America. In this study, movement of two consecutive trains as moving-blocks on a single railway line is modeled using a hybrid modeling technique known as Batches Petri Nets.

A new voting strategy in Diverse programming for railway interlocking systems

The main issue in controlling systems such as nuclear power reactors or railway systems is to provide safety at the highest level where risk ratio is high and sometimes small errors might result with death of several people. In order to improve reliability and keep safety of such systems at the required level by decreasing common cause failures at the same time Diverse programming (which is synonymous with N-version programming) technique can be used. In this study an example railway interlocking architecture is explained and a new voting strategy is also proposed.

Automatic Interlocking Table Generation for Railway Stations Using Symbolic Algebra

Abstract Interlocking is the most important component of a signalization system, which ensures safe travel and transportation. An interlocking system helps movement of trains on desired routes in fixed block signaling systems. The first step in the design of interlocking systems is to generate interlocking tables. Generation of interlocking tables for small scaled stations or railway yards can be realized easily. However, when the topology of the station is complicated, generation of the corresponding interlocking table becomes considerably difficult. In this study, a program that automatically generates interlocking tables for a given railway yard is explained. One of the main advantages of the program is that, switches and signal lights are placed automatically for a given station or railway yard depending on the topology.

Automatic Interlocking Table Generation for Non-ideal Railway Yards

Abstract Interlocking systems that can be regarded as the main decision making component of fixed block railway signaling systems, are directly responsible for ensuring the safe movements of trains. Software of an interlocking system depends on the interlocking table of the related railway yard. Although there are tools for automatic interlocking table generation, these tools generally do not consider non-ideal situations like non-signaled track or non-standard use of switches or signals. In this study, an efficient automatic interlocking table generation tool was proposed considering these non-ideal situations.

Signaling System Solution for Urban Railways: Esenler Railway Depot

Abstract Among other transportation alternatives, rail transportation is of great importance in urban transportation. Especially in crowded cities such as Istanbul where over thirteen million people live in, the use of urban rail transportation is inevitable due to traffic jam at peak hours. In this study, information about the first urban light rail transit M1 railway line is given and the signaling solution proposed for Esenler railway depot which is established in M1 railway line is explained.

N-version Programming for Railway Interlocking Systems: Synchronization and Voting Strategy

Abstract The main issue in controlling safety-critical systems such as nuclear power reactors or railway signalization systems where risk ratio is at the highest level because small errors might result in hazardous accidents (e.g. death or injury of several people) is to satisfy safety-related standards and provide high-safety with high-reliability. In order to improve reliability and safety of such systems to the required level by decreasing common-cause failures at the same time, diverse programming (or N-version programming) technique where N-different independently designed modules run in parallel on the same input output specifications can be used. In this study, a new bitwise voting strategy based on safe-states of variables is proposed and possible critical races between modules those run in a parallel manner are determined. Solutions for critical races are also explained.

Train Speed Control in Moving-Block Railway Systems: An Online Adaptive PD Controller Design

Abstract Since the overall capacity of railway lines are not used effectively in fixed-block railway systems, moving-block railway systems are introduced to increase the transport capacity and to reduce the headway times. CBTC (Communication Based Train Control) systems and ERTMS (European Rail Traffic Management System) application level 3 are regarded as examples of moving-block systems. In this study, the concept of moving-block system is explained and an adaptive PD control technique based on Online Least Square Support Vector Regression is used for train speed control.

Application of majority voting and consensus voting algorithms in N-version software

N-version programming is one of the most common techniques which is used to improve the reliability of software by building in fault tolerance, redundancy and decreasing common cause failures. N different equivalent software versions are developed by N different and isolated workgroups by considering the same software specifications. The versions solve the same task and return results that have to be compared to determine the correct result. Decisions of N different versions are evaluated by a voting algorithm or the so-called voter. In this paper, two of the most commonly used software voting algorithms such as the majority voting algorithm and the consensus voting algorithm are studied. The distinctive features of Nversion programming with majority voting and N-version programming with consensus voting are described. These two algorithms make a decision about the correct result on the base of the agreement matrix. However, if the equivalence relation on the agreement matrix is not satisfied it is impossible to make a decision. It is shown that the agreement matrix can be transformed into an appropriate form by using the Boolean compositions when the equivalence relation is satisfied.