Unfavorable conditions and predominantly higher speeds on ballasted rail tracks can cause the so called ballast flying. Especially in winter, it is considered to be highly probable that such phenomena are caused by the falling of snow adhering or ice accumulation on the surface of vehicles. As a result of the higher kinetic energy, the ballast stones upon the impact can lose their cohesion and slung away. When more clumps of ice are dis-engaged, these can lead to an intensified effect on general damages of vehicles (underfloor, vehicle surface, etc.) and on the infrastructure (signal masts, noise barriers, etc.). Furthermore ballast flying poses a serious threat to the people which are found close to the surrounding of the rail track (railway staff, pedestrians on the street or paths beside the rail track). Although this phenomena of the ballast flying is known since quite some time, the exact cause of it has not yet been investigated. Likewise, a system that identifies of the critical ice formation earlier during service and sends information to the infrastructure operator accordingly, is still not known.

With this study, the applicability and meaningfulness of a monitoring system for identification of the critical ice accumulation to prevent the ballast fly induced by ice dropping will be examined. This will be developed and tested in the field during the course of the subsequent project. Thus scientific research on the cause and the effects of the ice dropping, which are basis for definition of requirements and conception of a monitoring system (subsequent projects, dissertation) will be carried out. Furthermore the necessary basics will be gathered and the general applicability of this scientific part will be investigated.

Research Steps

In the study, initially, the following research steps will be performed:

• Environmental analysis: a survey on an international documented ballast flying incidents, including the boundary conditions prevailing in each case, such as travel speed, weather conditions, vehicle types etc. as well as a research of the international practice and development of counter measures in regard to this will provide a basis for further assessment.
• Basics for a mechanical modelling: collection of the important output parameters for a comprehensive modelling of the entire ice dropping processes (ice clumps, trajectory, ballasted tracks, impact and ballast fly) and a computer simulation. Subsequently, the fundamental influencing factors can be identified and their significance will be evaluated by a parametric study.
• Manual inspection of vehicles: through examination of the underfloor of individual vehicle in the ÖBB- workshops during winter season, the first knowledge will be gained on the scale, position and especially the characteristics of the snow and ice accumulation.
• Measurement of fundamentals: since there are no standard solutions for an automated knowledge of the ice and snow accumulation during the service, by means of the determined boundary conditions; the monitoring task will be specified, potentially suitable sensor components will be collected and compared each other, in regard with their characteristics.
• Intelligent monitoring system: the link of the available information are basis for the monitoring system. Here there is a need to clarify, how far the system can be in apposition to detect the hazardous situations and information (warnings) and produce actions and how to integrate them to the existing systems of the stake holder (especially infrastructure operator)
• Potential estimation: By means of structured problem analysis, the potential and applicability of the proposed ideas should be researched and at the end well-founded information should be available. Based on these well- founded information, it should be possible make a decision on whether and how the subsequent plan should be implemented.