Cross wind safety – Relative criticality of line parts and potential identification of non-critical lines/parts

Cross wind safety considers the possibility of trains overturning in strong winds. Methods for detailed line assessments have been derived, initially for high speed lines, but in principle applicable to all lines. The probability to overturn in cross wind is in general dominated by few exposed parts of a line, typically embankments and bridges, possibly in combination with a curve. Depending on the approach, it can be useful to determine the relative criticality of different line parts to find the most exposed parts of a line. High speed lines are likely to have more and higher embankments and bridges than conventional lines, which can better follow the terrain. In addition, long term positive operational experience is mainly on conventional lines. Therefore, it can be relevant to allow a simpler assessment of conventional lines, to determine if they can be considered safe without a detailed quantitative assessment. This paper presents an approach to derive a relative critical wind speed that includes the effect of different aspects influencing the cross wind criticality of a line segment, which can be compared to other segments. A way to derive a threshold value of the relative critical wind speed is shown, where the threshold value defines the limit value for non-critical or safe parts of a line. It can further be used to derive maximum height of embankments and bridges that for given conditions are safe without further assessment.