Longitudinal train dynamics

Longitudinal train dynamics (LTD) simulations have played an instrumental role over many decades in the development of longer trains, especially freight trains. Modern LTD simulations with individual vehicles considered and incorporating detailed modelling of couplings started during the 1960s. Since then, LTD simulators have been reported from all around the world. It is well known that the researchers and engineers widely used longitudinal train dynamic simulators in their projects and studies, but are there differences in these simulators and simulation approaches? Due to the commercial aspects and/or Intellectual Property issues, simulators were developed within separate institutions using developers' experience and limited testing data and publications. Currently, there are no standards or standard questions to assess the correct implementation of LTD analyses and the state of LTD studies. Given this situation, the Centre for Railway Engineering initiated the International Benchmarking of LTD Simulators (hereafter referred to as the benchmark). This special issue describes the benchmarking questions that have been sent to many research, commercial and government institutions and organisations across five continents and presents various papers that report on the approaches and advances in the topic of LTD. For all participants, this benchmark exercise offered a good opportunity to validate their research and access the expertise of other research institutions. More work will be necessary by researchers as this topic progresses with the analyses of all submitted results and contributions. Taking into account the current state of knowledge in this specific area and the editors' personal experience, researchers and engineers were invited to cover topics related to numerical and experimental studies with the application of LTD simulators and approaches for this special issue. These included issues related to locomotive/train and wagon/train interaction, train dynamics simulation, vehicle/track resistance modelling, and modelling the behaviour of air brake, coupler and draft gear systems. This list of topics can be extended because recent research activities show that this area requires implementation of multidisciplinary knowledge and approaches. Some of proposed topics have been extensively covered by this issue, but there are still a great number of topics left untouched in the special issue providing opportunities for further research and development in this field. We would like to thank all researchers who have participated in the benchmark and who have published their scientific ideas and developments. We hope that readers will enjoy reading the papers included in this special issue.