A framework for the consideration of the effects of crosswinds on trains

• Critique of existing CEN methodology for determining the risk of trains overturning in cross winds.
• New simplified and easily applicable methodology for train certification and route risk assessment, in which complex effects taken into account through second order corrections.
• Definition of parameter called the characteristic wind speed that determines vehicle overturning characteristics.

High winds have a number of different effects on the design and operation of trains, the most important being the need to design trains that will not blow over in high winds. The current European design methodology is contained within a draft CEN code of practice (CEN, 2009). In this paper the author will argue that there are inconsistencies and inadequacies in the approach adopted in that document, particularly in the levels of complexity of the different components and in the uncertainties that are involved. This leads to a proposal for a revised methodology that is more consistent in terms of the complexity of its components and can be used for train authorisation and route risk analysis. In particular the paper addresses the following issues:
• The development of simple correlations for train overturning moment coefficient as a function of yaw angle.
• The use of a simplified model of the train overturning phenomenon, which takes into account “real” effects (such as vehicle suspension, curvature, admittance effects and track roughness), through second order correction factors.
• The calibration of this model using previously published data obtained using more complex methodologies.
• The application of this methodology to risk based assessments for use in train authorisation and route risk analysis.
• The consideration of the uncertainty chain throughout the calculation process.Emerging out of this work, the concept arises of a simple parameter referred to as the characteristic velocity, which combines train geometry and aerodynamic effects and can be used as an indication of train safety in high cross winds.