The paper deals with computer support of safety analysis of railway control system corresponding to each stage of its life cycle, especially design, testing and maintenance. It is related to the reliability estimation of actually designed, manufactured or exploited from several years railway control systems. But is possible to analyze with computer support the occurrence of critical situations using FTA method, estimation of probability connected with such situations and verification of obtained results using simulation methods. The paper is final report of research works realized in Electronics&Diagnostics Department in Faculty of Transport and Electrical Engineering UTH in Radom.