A risk assessment method for ballast flight; managing the rolling stock/infrastructure interaction

Abstract

The evaluation of the level of risk resulting from the phenomenon of ballast flight is currently receiving considerable attention, due to its direct impact on the safety and reliability of commercial railway operations. Of particular interest are the effects of this phenomenon on both railway infrastructure and rolling stock. It is difficult to analyse the ballast flight phenomenon, due to its dependence on a large number of variable parameters. Investigations carried out at SNCF have led to the proposal of a global approach, called the stress-strength interference analysis method, which can be applied by considering a relevant indicator to evaluate the risk due to flying ballast. This paper presents the work on the application of the proposed analysis approach to the ballast flight phenomenon performed within the FP7 EU AeroTRAIN project. The approach considers the influence of the passage of dedicated rolling stock and the resistance of the track to the displacement of ballast. It leads to the proposal of a methodology to evaluate the risk of ballast flight in high-speed rail operations; this allows the evaluation of the degradation rate of railway infrastructure and rolling stock due to this phenomenon to be performed.

A computational fluid dynamics study of the influence of sleeper shape and ballast depth on ballast flight during passage of a simplified train

“…Studies of ballast flight increasingly adopt a statistical approach. [17][18][19] Stochastic variation in the wind parameters is calculated by the CFD analysis, and is reflected in the ranges of aerodynamic coefficients calculated and included in the presentation of the results. However, the aim of this study was to assess the effect of different sleeper shapes on the potential for solids of a regular and well-researched reference shape (cubes) to slide, roll or become airborne, and stochastic variation of the track or solid shape parameters was not a consideration.…”

“…The large number of factors potentially influencing ballast flight means that no one study has been able to address them all. Quantitative assessment is challenging, but methods have been proposed by Jacobini et al (2013) 10 and Saussine et al (2009) 11 which uses a stress-strength interference analysis to account for probabilistic nature of turbulent flow beneath the car body and of ballast particles becoming airborne.…”

A new methodology for assessing the actual number of impacts due to the ballast-lifting phenomenon

“…Neglecting the cases in which ballast-lifting phenomenon arose also at low speed due to external agents, e.g. ice or other scraps on the track, recent studies suggest that this issue begin to occur only at speeds of 270 km/h or greater, 9,10 when the pressure and the velocity field of the flow generated by the train in the upper layer of ballast could make the ballast stones be lifted up.…”

“…The AeroTRAIN project, in particular, studied a methodology to assess the interoperability of different trains using standard track conditions. 10,26,27 As a result, a method for risk assessment of ballast-flying phenomenon was presented 28 and a CEN norm was proposed (that was introduced in the EN14067-4:2013 as an informative annex a ) with a procedure for full-scale tests. Nevertheless, limit values and acceptance criteria were not defined.…”