This paper presents a methodology for improving the crossing (frog) geometry through the robust optimisation approach, wherein the variability of the design parameters within a prescribed tolerance is included in the optimisation problem. Here, the crossing geometry is defined by parameterising the B-spline represented cross-sectional shape and the longitudinal height profile of the nose rail. The dynamic performance of the crossing is evaluated considering the variation of wheel profiles and track alignment. A multipoint approximation method (MAM) is applied in solving the optimisation problem of minimising the contact pressure during the wheel–rail contact and constraining the location of wheel transition at the crossing. To clarify the difference between the robust optimisation and the normal deterministic optimisation approaches, the optimisation problems are solved in both approaches. The results show that the deterministic optimum fails under slight change of the design variables; the robust optimum, however, has improved and robust performance. © 2016 Taylor & Francis

Railway crossings are important operational elements in railway infrastructures. The discontinuity in the rail geometry at the crossings results in high impact loads. These dynamic forces can cause severe damage to the crossings. The goal of the research is to develop a methodology that optimises the vehicle-track interaction at railway crossings by tuning the crossing design, which ultimately leads to increased availability and lower costs of the railway network. Optimisations in the traditional railway system design is carried out in a primitive way by modifying the design parameters, mostly based on the designer’s experience, and repeated numerical analyses. In the methodology developed here, the crossing design improvement is performed systematically by using numerical optimisation techniques to solve problems with multiple criteria, design variables, and constraints. The optimisation focuses on the reduction of damage to the crossing, especially that by rolling contact fatigue (RCF), from impact forces. In order to achieve this reduction, the geometry of the crossing and the vertical elasticity of the crossing are optimised. The assessment of the crossing design is based on dynamic analyses of the train-track behaviour using the multibody simulation method and the finite element method, which in the design improvement process were coupled with the optimisation technique. Moreover, the developed methodology is extended to solve optimisation problems with parametric uncertainties, such as tolerance of design parameters. For this purpose, the robust optimisation method is used, which results in robust optimum solutions. This study provides guidance for both the production of new crossings and the maintenance of existing crossings.