Influence of Operator on Safety of the Signalling System during Emergency Operation

A signalling system is a technological instrument for railway transport process controlling and its role is to replace or check human (operator of the signalling system) in applying the safety critical operations related to railway traffic control. The aim of such replacement or checking is contribution to safety of the railway transport so that the signalling system eliminates errors of operator. Because of continuous character of operation control of the railway transport process, there is a need to ensure control of the railway transport in the case of partial or total failure of the signalling system. An objective assessment of the operator's influence on railway transport safety (especially in the case of not availability of one or more safety functions) is possible only on the quantitative model base. Creation of such model requires not only knowledge of the signalling system technical design, but the specific data about it what safety critical commands are used by operator and the frequency of their using by the operator too.