Research On Safety Analysis And Verification Method Of Tram Signal System

The tram signal system is the core system that guarantees the safe operation of trams.It is also the most important part of the tram system.It can not only command the tram operation,but also assist the driver in driving and protect the security of people in the vehicle.The tram signal system is composed of many subsystems and belongs to a complex system.With the rapid rise and development of modern trams at home and abroad,many hidden risk factors are gradually exposed.In recent years,many new functions and technologies have been applied in tram systems,which has added to the complexity of the risk factors in the operation of the system.However,there are few specifications for trams in China,which also makes the signal system of trams Security risk assessment becomes extremely urgent.This article takes modern signal systems of new trams as objects.Starting from the system-wide aspect,the system conducts security risk assessment,and uses cloud models,optimal combination weights,risk matrix and other theories to assess the safety factors and safety risks of the system.Conducted in-depth research,and based on the analysis results proposed improvements to the system's security features.It has certain reference value for ensuring the safe operation of tram signal system and realizing the diversification and orderly development of rail transit in China.The main research contents in the thesis are:First,taking Shanghai Songjiang line Tram as an example,the tramway signal system is comprehensively analyzed.It consists of a main track switch control subsystem,a junction priority control subsystem,an depot interlock,an on-board system,as well as a central operation dispatch system.By describing the working modes of each subsystem and their main components,this article take the use of the turnout control subsystem as an example,analyze the system's functional safety and risk identification,laying the foundation for subsequent analysis of system security factors;Secondly,it briefly introduces the existing methods of security assessment,and points out the defects in the existing methods.Then it proposes the security assessment methods used in this thesis and the analysis method based on the weighted cloud model.In the evaluation process,the qualitative concepts corresponding to the ambiguity and randomness of the risk can be converted into quantitative values,and a cloud generator can be generatedthrough the cloud generator so that the analysis result is more accurate and intuitive.In addition,this thesis uses an improved weight determination method,the optimal combined weight method.This method makes use of the optimal combination with the smallest variance,and combines the subjective weights and the objective weights reasonably together.The resulting weight values contain both objective data information and subjective empirical values and credibility.In order to verify the correctness and feasibility of the assessment methods listed in this paper,this thesis analyzes the Shanghai Songjiang line tram signal system step by step and calculates the risk severity and risk potential of the system.The risk likelihood assessment cloud model of the system and the similarity comparison result between the risk assessment cloud model and the assessment standard cloud model are used to determine the system's risk severity level and risk probability level,and the two levels are combined to compare the risk matrix.It is possible to derive the risk tolerance level of the system.Finally,in order to meet the growing social needs,this article combines the unique characteristics of modern trams,and proposes several improvements that can reduce risks in the fault-tolerant function of the tramway signal system evaluation system.Including the improvement of automatic alarm,overspeed protection,and advance protection,the development of trams is becoming more intelligent and has higher security.