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1

Effective time interval for railway track geometry inspection

Kasraei Ahmad, Zakeri Jabbar Ali

Archives of Transport

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2020

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Vol. 53, iss. 1

53--65

EN

A proper decision-making scheme for track geometry maintenance requires a knowledge of the real condition of track geometry. Therefore, the track must be inspected by measurement cars at different time intervals. The frequency of track geometry inspection plays a crucial role in decision-making and has always been a big concern for infrastructure managers. The inspection interval should be chosen properly, it means that the small period can decrease the capacity of line and affect the operation of network and the big period can result in low quality of track and in some cases derailments and possible loss of human lives. The aim of this paper is to determine the effective inspection interval such that the total maintenance cost is minimized. In the proposed cost model, the costs of inspection, preventive maintenance, corrective maintenance and the penalty for exceeding the corrective maintenance level are considered. A case study is performed on a real dataset collected from a railway line in Iran. The standard deviation of longitudinal level is considered to measure track geometry degradation. A widely applied linear model is used to model track geometry degradation over time. Monte Carlo technique is used to simulate the track geometry behavior under various track geometry inspection intervals. In addition, a set of sensitivity analyses are carried out to assess the effect of various inspection intervals on different terms of maintenance cost. The results indicate that not only can substantial costs be saved by setting effective inspection intervals, but also the time during which the track suffers from bad conditions is dramatically reduced. The result of this study has shown the appropriate inspection interval for the studied case can result in 13.6 percent decrease in maintenance cost in comparison with the current maintenance policy. Besides, it would lead to more reliable railway track by preventing the system exceed the corrective threshold.

2

An approximate economically optimal inspection interval for production processes with finite run length

Deeb A. M., Hryniewicz O.

Control and Cybernetics

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2008

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Vol. 37, no 1

191-204

EN

Increased competition on the global market forces producers to follow policies leading to finite production runs. This situation requires implementation of a new type of inspection procedures with the aim to improve or sustain production quality levels. One of the most important aspects in the design of inspection processes is the specification of inspection intervals. This paper provides a simple procedure to determine an approximate optimal inspection interval h for a given inspection plan, characterized by its probability of type-I error a and probability of type-II error β, for processes with finite run length.

3

Planning inspections in service of fatigue-sensitive aircraft structure components under crack propagation

Nechval K. N., Nechval N. A., Berzins G., Purgailis M.

Eksploatacja i Niezawodność

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2007

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nr 4

3-8

EN

For important fatigue-sensitive structures of aircraft whose breakdowns cause serious accidents, it is required to keep their reliability extremely high. In this paper, we discuss inspection strategies for such important structures against fatigue failure. The focus is on the case when there are fatigue-cracks unexpectedly detected in a fl eet of aircraft within a warranty period (prior to the fi rst inspection). The paper examines this case and proposes stochastic models for prediction of fatigue-crack growth to determine appropriate inspections intervals. We also do not assume known parameters of the underlying distributions, and the estimation of that is incorporated into the analysis and decision-making. Numerical example is provided to illustrate the procedure.

4

Approximately optimal simple inspection strategies

Hryniewicz O.

Journal of KONBiN

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2006

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No. 2

123--132

EN

In the paper we present a very simple method for finding an approximately optimal strategy of inspections of an equipment whose failures are not directly observable. The optimal inspection interval can be found with a limited amount of information using simple computational methods. We consider also the impact of imprecise input information on the computed values of optimal inspection periods. In such a case we describe imprecise numerical information by fuzzy sets, arriving at the imprecise (fuzzy) optimal inspection interval.