Numerical analyses for the assessment of infrastructure requirements for tramcar safe operation

Nowadays urban vehicles have become more and more important in public transportation, this have lead to the development of new generations tramcars with structural configurations and design solutions (e.g. articulated bogie frames, independently rotating wheels) which can significantly improve comfort, capability and accessibility. Moreover the suburban tramways that are growing up, are often characterised by dedicated rights-of-way, equipped with Vignole rails. For these reasons a careful analysis of vehicle running safety is required, with particular respect of derailment risk, besides other topics such as riding comfort and vehicle stability and line maintenance. Maintenance of tramcar lines, actually, represents one of the major issue for urban transportation authorities. In fact, beyond their actual costs, maintenance activities may require intervention on the road yard, leading to a deep impact on urban mobility and what is more can deeply affect the comfort and the running stability of the vehicle. Thus it is important to point out the most important characteristics a line must have in terms of irregularity in order to guarantee the main running dynamics performances and safety. This work is aimed to provide an effective tool able to identify the influence of track degradation on the running safety (wheel climb) of a modern tramcar equipped with independently rotating wheels. By means of a dedicate multi-body model, tramcar dynamic behaviour in different running conditions (e.g. different curve radius, speed ) can be investigated taking into account various track defects amplitude and shapes. In the paper, after a brief description of the mathematical model of the vehicle, with particular attention to the wheel/rail contact model (par. 2) as the methodology for the evaluation of the vehicle safety running behaviour (par. 3) and the obtained results are reported (par. 4).