Hardware-in-the-loop simulation (HILS) is one of the high-tech approaches that combines theory, numerical simulation, software, digital communications, data acquisition, instrumentation and control to give a mechatronic system. Such a system can be utilised to simplify development and design processes for complex systems as well as their testing and validation, which allows reduction or, in some cases, avoidance of the high cost of real field tests. It is well known that the automotive industry has implemented HILS widely in their research projects and investigations, but what is a situation with HILS in railway research? Recent publications [1–7] show that the quantity of papers in this field is significantly increased and it is possible to predict that, over the next 5–10 years, HILS will be one of the most required tools for rail vehicle design, much as multibody software is at the present time. For the development of HILS solutions, researchers should have deep multidisciplinary knowledge and a good background in mechanical, electrical and computer science. The components of HILS solutions for rail applications are almost the same as for automotive ones, but the rail vehicle presents additional challenges as it is more complex and contains many more non-linearities and uncertainties. In addition, the common use of friction damping components in rail suspensions present more challenges to the numerical solvers and calculation speed. One key area of research is how to achieve numerical solutions of existing wheel/rail contact models at sufficient speed for real-time applications. Another issue is how to take into consideration the train dynamics (many vehicles are involved in the train operation process)? Or more, how to develop a real-time model in order to describe the contact mechanics for pantograph systems and how to test them? The list of uncertainties can become very lengthy.