Analysis of Failures of Automatic Level Crossing Devices

The safety of automatic level crossing devices (ALDs) is of utmost importance due to the need to ensure safe passage through railway crossings—accidents must not be allowed. In this paper, an analysis of failures of ALDs in the railway infrastructure in Bulgaria for the period 2020–2022 is performed. First, a statistical evaluation of failures and their duration are calculated. Then, simple reliability indicators have been defined (the time for failure-free operation for different periods, the statistical assessment of the intensity of the failures flow and MTBF) in two ways—considering all failures and their duration or only those due to technical reasons. Finally, the coefficients of availability and unavailability are determined (also in both ways). A comparison was made with the availability coefficients of the indoor devices. The results obtained can be used in determining guidelines for the reconstruction and renovation of signaling systems and railway lines, as well as in identifying conflict points where multi-level crossings should be implemented. It should be noted that performing only a statistical analysis is not enough, it is necessary to determine the reliability indicators and, above all, the availability coefficient.