Nowcasting and Forecasting tecniques for railway switches maintenance

A large proportion of the costs of the European railway Infrastructure is related to maintenance and the current situation of railway maintenance .

The increasing usage of the railway infrastructure, due to a growing frequency of passenger and freight trains on it, and environmental and safety regulations, the increasing of maintenance requirements cannot be met without a substantial shift in maintenance strategies.

In this prospective, the new “Proactive/Predictive Maintenance”  approach will involve/have an impact all the main railway stakeholder on long-term preservation of assets (expressed in RAMS requirements) minimizing life cycle costs, while for the railway operators, the proactive maintenance will improve the railway infrastructure availability and reliability.

Switches and Crossings (S&C) are fundamental infrastructure assets that allow efficient routing of trains on the network. Assessing their current status and ensuring their proper functionality is obviously a key requirement to guarantee the railway infrastructure availability for the railway operators. For these reasons, Ansaldo STS tries to discover in the Mantis project, references concerning railway S&C condition monitoring based on a wide range of methodologies from the world of statistics, data mining, time series analysis, machine learning, and filtering.

Given the examined literature, it seems clear that the use of the word “nowcasting” can be associated with: a shorter timeframe respect to “forecasting”, a different approach or algorithm for performing the estimation of the value of interest, the fact that the data used for the estimation is imprecise, uncertain, incomplete or is only indirectly related to the phenomenon of interest, and, finally, with the purpose of providing an alert for a sudden event or a possible anomaly.

A reasonable simple definition could be adopted in the framework of the Mantis project for differentiating “forecasting” and “nowcasting” processes:

Forecasting:

The process of exploiting past and present data to make deductions about the future.

Nowcasting:

The process of exploiting past and present uncertain or incomplete data to make deductions about the present.

Many of the failures are not detected until the asset is being operated by the interlocking system when trying to lock the train route. This means that for some failures, nowcasting cannot be done before operating the unit. Frequent test procedures could solve this issue but it has other disadvantages like the introduction of increased wear, cost and reduced inherit capacity. Another solution for this problem is to introduce additional condition monitoring systems for detection of different states of critical components in the S&Cs.