A study of the effect of variations in bogie centre distance on rail car roll performance

The directional changes of the vehicles imply different effects as a consequence of the resulting lateral accelerations exerted on the vehicles, regardless of the type of transport. In the particular case of railway transportation, such effects include rail wear and accidents such as derailments and rollovers, as any direction change represents a transient perturbation to the vehicle during which its stability can be compromised, especially if relatively small radius curves are involved. As a general condition, turning-related lateral inertial forces have to be balanced by the vehicle and infrastructure components, as a function of vehicle's operating conditions (mass and speed) and infrastructure's geometrical characteristics. In this paper a mathematical model is proposed to analyze the effect of rail car's bogie centre distance (BCD) on the transitional radius of curvature and the resultant lateral accelerations and vehicle performance. Results reveal significant changes in transitional radiuses for variations of BCD that have, nevertheless, small effects on the lateral stability of the rail car but that can signify, as an accumulative effect and at long term, important variations of the aggregated forces on the rails, on the order of +1% to +2% for the first fully loaded 200 cars when vehicles with a BCD distance of 6.76 m are selected instead of vehicles with a BCD of 15.86 m.