Otomatik yarım bariyerli hemzemin geçit sisteminin kontrolü ve risk modelinin oluşturulması
Automatic control of half barrier level crossing systems and to set the risk model
Yazar: OĞUZ KIRBIYIK
Danışman: PROF. DR. MEHMET TURAN SÖYLEMEZ
İstanbul Teknik Üniversitesi / Fen Bilimleri Enstitüsü / Kontrol ve Otomasyon Mühendisliği Ana Bilim Dalı
Derece: Yüksek Lisans, 2016
Konu: Mühendislik Bilimleri = Engineering Sciences

Özet:
Gelişmiş toplumlarda raylı ulaşım sistemleri önemli bir ulaşım alternatifi şeklinde kullanılmaktadır. Günümüzde raylı ulaşım sistemi araçları gerek yolcu taşımacılığında gerekse lojistik taşımacılığında önemli bir noktada bulunmaktadır. Diğer alternatif ulaşım araçlarına kıyasla daha güvenilir ve daha hızlı ulaşım imkanı sağlamaktadır.
Demiryolu sistemlerinin gelişmesi ile beraber demiryolu sistemlerinde güvenlik önlemleri özel olarak önem kazanmıştır. Daha az maddi kayıp ve can kaybı işletmecilik açısından önemli olmaktadır. Demiryolu sistemleri bünyesinde bulunan hemzemin geçit sistemleri de bu güvenlik sistemlerinin önemli bir bölümünü oluşturmaktadır. Özellikle hemzemin geçit bölgesi karayolu ile demiryolunun kesişim noktasında olması sebebiyle can ve mal kaybının yüksek olduğu bir yerdir. Bu bölgede bulunan sistemlerin güvenlik önlemleri demiryolu sistemleri açısından özel önem taşımaktadır. Alınması gereken tedbirler ve hatada güvenli sistemlerin inşa edilmesi önemli bir yer oluşturmaktadır. Özellikle hemzemin geçit bölgesinde bulunan sistemlerin emniyet ve risk analizlerinin yapılması insan kaynaklı hataları minimuma indirecek hatta hiç olmamasını sağlayacaktır. 
Hemzemin geçit sistemleri özellikle ülkemizde bulunan demiryolu sisteminin önemli bir bileşenini oluşturmaktadır. Tez çalışmasında hemzemin geçit sistemleri genel olarak tanımlanmıştır. Çeşitleri hakkında bilgiler verilmiştir. Donanımsal ekipmanları hakkında tanımlamalar yapılmıştır. Karayolunda ve demiryolunda bulunması gereken işaret ve işaretçilerin önemi anlatılmıştır. Hemzemin geçit bölgesinde yapılması gereken risk analizinin nasıl yapılması gerektiği anlatılmıştır. RAMS yönteminin tanımı ve uygulaması örnekler verilerek anlatılmıştır. Risk analizinde kullanılması gereken teknikler ve metodlar üzerinde durulmuştur.
Bu tez çalışmasında, otomatik yarım bariyerli hemzemin geçit sistemine ilişkin risk analizi yapılmıştır. Hemzemin geçit sisteminde risk indeksi belirlenmiştir. Risk analizi, FMEA ve FTA analizi yöntemleri kullanılarak hemzemin geçit sistemi için olası hata senaryoları tanımlanmış ve hata oranları belirlenmiştir. Özellikle yarım bariyerli hemzemin geçit sistemlerinde bulunan zigzag durumun engellenebilmesi için ne gibi tedbirlerin alınması gerektiği belirtilmiştir. 'V' modeli kullanılarak sistem yaşam döngüsünde bulunan her bir adım kontrol edilmiş ve hemzemin geçit sistemindeki hata oranları minimuma indirilmiştir. Hemzemin geçit bölgesinde SIL güvenlik sistemi analizi yapılmıştır. Otomatik yarım bariyerli hemzemin geçit sistemi için olması gereken sistem isterleri belirlenmiş ve otomatik yarım bariyerli hemzemin geçit sistemi tasarımı yapılmıştır.

Abstract:
In the developed countries, rail transport system are used as an alternative to major transportation. Today rail transit system vehicles are at a critical position in passenger and logistic transportation. These vehicles are more secure and more comfortable than other alternatives and also they provide faster transportation.
Today rail transport system is very important. Rail transit system is used for passengers and cargo. The train provides less financial requirement and it carries more material other transport vehicles.
Rail transport system is a system used to control railway traffic safely to prevent trains from colliding. Trains are uniquely susceptible to collision since they frequently operate at speeds that do not enable them to stop quickly or within the driver's sighting distance. Railway signalling system process is traditionally carried out in a signall box. These are placed at various intervals along the route of a railway, controlling specified sections of track. With the development of technology, railway signalling system has made such operational doctrine superfluous, with the centralization of signalling operations to regional control rooms.
Level crossing is an intersection where a railway line crosses a road or path at he same level. Trains have a much larger mass relative to their braking capability, and thus a far longer braking distance than road vehicle. They do not stop at level crossings but rely on vehicles and pedestrians to clear the tracks in advance. Possible accidents of trains include derailment, a collision with another train or collision with automobiles, other vehicles or pedestrians at level crossing.
There are different types of level crossings. One of which are full barrier crossing. The barriers are normally kept raised. When a train approaches, a warning will sound and the lights will show amber and then flash red. Some barriers are automatic, while others are operated by railway staff. Second one are automatic half barrier crossing. When a train approaches, a warning will sound and the lights will show amber and then flash red. Then the barriers will close across the entrance to the crossing, leaving the exit clear. The other one are gated crossing operated by railway staff. The crossing is operated by railway staff in the signal box next to it. When train is coming, they close the gates across the road. Fourth are automatic open crossing with lights. The lights and warning sound are set off automatically by an approaching train. The train will cross when driver can see that crossing is clear. It has received an indication that the crossing equipment is working normally. The last one are open crossing. Open crossings are only situated where there is enough time for you to see if a train is coming and cross safely.
  
Level crossing system has a very important in rail transportation. The rail transport system has a lot of level crossing in Turkey. Level crossing system is the intersection of road and railway. Therefore, there are many accidents. Especially, safety has gained more importance in rail transport system. That's why, railway system engineers focus on the safety analysis. 
Rail transport systems begin to use automatic control system. Relay interlocking system was abandoned and replaced by more reliable software products. Faults in the rail transport system can be easily detected because of railway signalling system.
By the development of railway systems, safety precautions have gained importance significantly. Less financial damage and less loss of life have become more significant in railway businessment. Level crossing systems included in railway transportation are an important part of these safety systems. Especially level crossing area is a location that occurs too much loss of life and property. Safety precautions for this area are more significant for railway systems. Precautions and building fail-safe systems occupy an important place. Especially making safety and risk analysis of systems in level crossing area, reduces human-driven faults even it provides zero error. 
With the development of railway technology, safety has gained more importance. Athough there are many studies so far safety and risk analysis in railway systems, level crossing systems are not studies safety and risk analysis.
Especially in our country, level crossing systems are significant components in railway systems. In thesis study, level crossing systems are defined in general and given informations about types of the system. Hardware equipments of them are defined. Importance of roadway and railway signs and signals are described. It is also mentioned how risk analysis on level crossing area shall be done. Description and implementation of RAMS method are shown with examples. Techniques and methods for risk analysis is explained as well.
RAMS management is determining to combine reliability, availability, sustainability, and safety with system engineering proccess. It provides to ensure to implement designated railway timetable. Rail transport systems are designated railway timetable well-timed, reliably and cost efficiently. This stiation has an important creating advantages. RAMS management is a very crucial subject in railway transport system.
It was used many standard for RAMS management. It was created based on BS IEC 61508 standarts. Its content has reprentative standards for safety management of electric/electronic related system. 
RAMS management standard haver been developed by CENELEC. It is clear that the reliablitiy of a railway signalization system is directly related to interlocking system. Therefore, safety standards are based on BS IEC 61508 standards. Besides, safety standards called BS EN50126, BS EN50128 and BS EN 50129. They are created by CENELEC to define general safety requirements for the railway interlocking systems. BS EN50126 included RAMS management basic principles and applications. It was published in 1999. BS EN 50128 was published in 2008. It has a RAMS management standard for software used in operating, signalling, and communication of railway signalling system. BS EN 50129 was published in 2003. It has a RAMS management standard on railway signalization system hardwares.

RAMS is a railway signalling system's long term operation. It is established engineering concepts, methods, tool and techniques. It has the lifecycle of the railway system. The RAMS of railway system is influenced in three ways. These are system conditions, operating conditions and maintenance conditions. RAMS requirements are based on the concept of taking precautions to minimize the possibility errors during the lifecycle phases. Precautions are influenced in two ways. These are prevention and protection. All RAMS parameters used should be agreed between the Railway Authority and the Railway Industry.
The concept of risk is the probability of occurence of an event or combination of events leading to a hazard and the consequence of the hazard. Safety integrity can be viewed as a combination of quantifiable elements and non-quantifiable elements. They have hardware, software, specification and documents. Safety integrity level (SIL) is defined by IEC 61508 standard.
The system lifecycle is a sequence of phases. These are tasks and the total life of a system. The lifecycle provides a structure for planning, managing, controlling and monitoring. The lifecycle representations are widesprad within industry like nuclear plants and railway systems. There include the 'V' model. The 'V' representation is effective in showing verification and validation tasks within the lifecycle. The objective of verification is the deliverables of each phase meet in all respects the requirements of that phase. The objective of verification is the system under consideration, at any step of its development and after its installition, meets its requirements in all respects.
RAMS managements have the different stages of hazard analysis. There are rapid ranking analysis, structured what if analysis, hazard and operational analysis (HAZOP), failure mode effects analysis (FMEA), event tree analysis (ETA) and fault tree analysis (FTA). Rapid ranking is focussed on the most significant hazards. Structured what if analysis is easy to understand, flexible and easy to be unstructured. Hazard and operational analysis (HAZOP) is a structured method for identification risks invented in the chemistry industry. Failure mode effects analysis (FMEA) may be a large system or a single physical component. It includes processes, functions, software, hardware and human errors. Event tree analysis (ETA) analyses the occurence of an event. It is used to analyse the consequences of failure events. Fault tree analysis (FTA) is the interaction of system, subsystem and component failures. It described in IEC 61025.
In this thesis study, it is made risk analysis for automatic half-barriered level crossing system. Risk index in level crossing system is specified. Possible failure scenarios for level crossing system and failure rates are defined by using FMEA and FTA risk analysis methods. Especially, precautions for blocking zigzag position at automatic half-barriered level crossing system are specified . Each step in system life cycle is controlled by using 'V' model and failure rates on level crossing system are reduced as minimum. SIL safety system analysis is done on level crossing area. System requirements for automatic half-barriered level crossing system is specified and lastly automatic half-barriered level crossing system is designed.