Our nation is one of the advanced countries in high-speed railway. The performance of its interlocking system is crucial to driving safety and efficiency, so, it’s urgent to research the safety assessment of the system. Based on the situation that we don’t have a mature evaluation scheme to carry out the safety assessment, the paper researched several generally used assessment methods and their implementation, driving the transformation of its safety management from the mode of security assurance based on technical manual to the form of safety assessment based on overall life- cycle.First, the paper researches related assessment contents, including SIL, risk matrix, risk control, the structure of high-speed railway signal systems and the condition of safety assessment.Then, several assessment methods- PHA, expert assessment, FMEA, ETA and FTA- are researched. Further, the paper researched how to choose the methods via analysis, summing up 5 key points- the system scale, using experience, the certainty of specific parameters, the demand of assessment, and the period. The example of ETA analysis in the ATP introduced its implement, major in modeling and calculating. The use of FTA in the CBI- designed by the institute of Beijing communication signal- elaborates how to set parameters and compute failure rate.On account of the absence of objectivity and accurancy in expert evaluation results, combining with which the paper uses AHP and Grey Theory to put forward safety assessment. The example of its application to a CBI shows the implementation of this evaluation method. Based on theory research, the paper sets goal level, criterion level and index level, and calculates risk matrix of index by grey evaluation matrix and weight vector. Then, the weight vectors of the criterion level and risk matrix are used to compute membership matrix, and the risk level of the system can be reasoned out. The evaluation result shows that the risk of this system is between ‘tolerable’ and ‘undesirable’. And through the total sequencing, the most influential elements are CPU, acquisition control panel, alarm board and violation operation. On this basis, precautionary and improvement measures are proposed.Chapter two shows that the implement of safety assessment usually concerned Markov process and a large amount of calculation, so, the paper bring in an assistant reliability analysis software- Isograph, which is composed of reliability and availability workbench. The former supports ETA, FTA, Markov and maintenance analysis. Through modeling and analyzing in the CBI assessment, this paper introduces how to use Isograph. The failure rates of the interlocking unit and communication card are in accordance with chapter 2. Through the calculation of the failure rate of the top event, a conclusion is drawn that this system meets the requirements of our country.Although the paper puts forward strategies to choose evaluation methods according to specific circumstances, and adopts AHP and Grey Theory to assess the CBI, there are still some flaws and deficiencies. For example, the FTA process ignores common-cause failures, viewing each breakdown as a solo part. Moreover, expert evaluation is full of subjectivity, so, how to choose assessing experts and how to establish grading criterion require further research. |