An automated digital method for the assessment of crosswind safety for the HS2 route

Strong crosswinds have been known to overturn trains. High-speed trains can be especially at risk because the higher the train speed, the lower the critical wind speed at which overturning occurs. The risk of overturning varies at different points along a given route and is influenced by the exposure of the track (for example, on high viaducts), the speed of the train, cant deficiency in curves, and other factors.

In order to ensure a resilient railway operation, the risk is managed by a combination of civil engineering mitigation measures such as the provision of wind barriers, and operational mitigation measures such as reduced operating speeds during extreme wind conditions. Calculation of the risk at each point along the route is a necessary step in the evaluation of different mitigation scenarios. Since the calculations are intensive and need to be repeated for each mitigation scenario or to reflect a developing design, an automated method is preferred.

This paper presents the methodology used in a crosswind risk study for High Speed Two (HS2). Firstly, the basis of the calculations is presented. The methods are based on a Rail Safety and Standards Board (RSSB) standard with adaptations for consistency with current European practice in which train stability in crosswinds is described by Characteristic Wind Curves, and to account for recent advances in meteorological data. Secondly, the implementation of the calculations is presented. An automated digital solution has been developed which imports input information from multiple sources, including design and geographic data from GIS, and performs the risk calculation at 20m intervals along the route. The calculation results are fed back to GIS enabling presentation of the distribution of crosswind risk along the route in the form of colour-coded maps from which any risk hot-spots can be identified in the context of their local geography. Because the calculation is automated, it can be rerun easily to evaluate different mitigation scenarios or when new design data becomes available and is applicable to future stages of HS2 or other new railways in the UK. Furthermore, rigorous and consistent use of live design data reduces the likelihood of localised risk hotspots being missed.