Development of a modelling framework for running safety analysis of a heavy-haul freight vehicle crossing a bridge under different loading conditions

Abstract

Evaluation of train running safety for freight and heavy-haul railway vehicles is a poorly addressed topic in the literature, despite their distinct dynamic behaviour and track conditions compared with passenger and high-speed railways. For this purpose, a framework for the development of a three-dimensional numerical analysis of train running safety crossing a bridge using a vehicle-structure interaction methodology is presented. Numerical models of the railway bridge were developed and calibrated, and multibody models of the heavy-haul vehicles were created and optimised based on modal data. Structure and vehicle dynamic responses were obtained using the dynamic interaction models that consider nonlinear wheel-rail contact models. Assessment of structural and train running safety was performed for multiple train speeds for both loaded and unloaded vehicles using different degrees of rail geometric irregularities based on the Federal Railroad Administration's power spectral density functions. The case study is a 550-metre-long railway bridge composed of 22 simply supported steel-concrete composite spans, crossed by heavy-haul vehicles of the gondola-type wagon with 375 kN axle loads. The safety of the bridge was assessed in terms of structural responses according to European codes, while the running safety of the vehicle was evaluated through indirect running safety indices as well as direct derailment coefficients based on vertical and lateral wheel-rail contact forces and more advanced criteria. It was found that in regular operational conditions, all indices are well below recommended limit values for loaded vehicles, whereas the unloaded vehicles presented a more unstable dynamic behaviour.