Method of evaluation of the railway track’s availability for traffic operations

Aim. The maintenance of Russia’s railway network requires significant expenditures in order to support the dependability of infrastructure facilities operation. When resources are limited, a wrong decision can cause errors in maintenance planning. The activities of track enterprises define normal operation of the railway infrastructure as a system. Rational management of infrastructure facilities requires the availability of objective real-time information on their dependability and functional safety. One of the key indicators that characterizes the dependability of track is the availability coefficient. When evaluating partially available facilities, it must be considered how partial non-fulfilment or reduced quality of its functions impacts the availability. The conventional formula for the technical availability coefficient allows for only two possible facility states: operable and non-operable. Such evaluation of the technical availability coefficient does not, for instance, allow for reduced availability as a result of a speed restriction on a line section, as well as the impact of a failure of a line section on the overall availability of the line. Therefore, this article deals with the method of evaluation of the technical availability coefficient of a line section subject to its partial operability, as well as considers the approach to the standardization of the technical availability coefficient of a line section.

Methods. The evaluation of the technical availability coefficient of a line section subject to its partial operability involved a system analysis of factors that reduce track capacity. Among such factors are speed restrictions and interruption of traffic due to scheduled and non-scheduled maintenance operations. A three-dimensional graphic model of dependency of movement speed from linear coordinates and time is suggested. It was used to deduce the formulas for evaluation of the technical availability coefficient of single and n-track lines. An approach to the standardization of individual components of the technical availability coefficient was considered. Correlations were deduced for calculation of standard value of the technical availability coefficient of single and n-track lines.

Conclusions. Upon an examination of the factors that cause partial operability and non-operability of railway track, the authors offer a method for evaluation of the technical availability coefficient of a railway line subject to the effects of speed restrictions on the capacity and thereby the availability of track. Aspects of standardization of the technical availability coefficient were examined. Formulas were obtained that allow calculating the actual availability coefficient of a railway line subject to partial operability, as well as the standard value of this indicator. The approaches and methods that are considered in this paper aim to improve the objectivity of evaluation of track availability to enable well-founded decisionmaking in operation. 

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