This paper is an outcome of an international collaborative research initiative. Researchers from 24 institutions across 12 countries were invited to discuss the state-of-the-art in railway train air brake modelling with an emphasis on freight trains. Discussed models are classified as empirical, fluid dynamics and fluid-empirical dynamics models. Empirical models are widely used, and advanced versions have been used for train dynamics simulations. Fluid dynamics models are better models to study brake system behaviour but are more complex and slower in computation. Fluid-empirical dynamics models combine fluid dynamics brake pipe models and empirical brake valve models. They are a balance of model fidelity and computational speeds. Depending on research objectives, detailed models of brake rigging, friction blocks and wheel-rail adhesion are also available. To spark new ideas and more research in this field, the challenges and research gaps in air brake modelling are discussed.

European trains are equipped with a pneumatic braking system that has to respect severe specifications concerning both performances and safety. The pneumatic braking system is composed of hundreds of different pneumatic components that reproduce the prescribed response by a complex logic of pneumatic and mechanical elements. In this paper a tool for a complete simulation of the pneumatic braking system is described, it was developed using the Matlab-Simulink numerical environment. The tool is composed of three different libraries of pneumatic components. The first includes the elementary components such as pipes, orifices, valves and the reservoir. By assembling elementary components, an advanced user can build a customized version of general pneumatic components or plants. Complex components of general use for railway pneumatic brake such as brake cylinders, distributors, pressure transformers and brake valves are available in a second library that can be used to assemble a customized braking plant for a vehicle. The last library is composed of macro-pneumatic subsystems that reproduce the braking system of a typical railway vehicle. Many common plant layouts are reproduced in this library (freight car, passenger coaches, locomotives, etc.). The pneumatic brake system of a train can be simulated by assembling in a single Matlab-Simulink model the elements of the library. In this paper the main features of this numerical tool and the test procedures developed to validate the software are described. Experimental data have been kindly supplied by Trenitalia SPA and they are referred to several test campaigns managed by Italian railway in order to verify and release existing components of the pneumatic brake.

In high-speed trains, current collection from the overhead line is assured by an articulated suspension system called the dasiadasiapantographpsilapsila Contact wires and overhead line are flexible systems that are subjected to oscillations that have to be compensated for a satisfactory quality of current collection. In high-speed railway applications, this technical problem is very important since higher traveling speed involves higher oscillations of the catenary. A feasible solution to improve current collection quality is to optimize the dynamical response of the pantograph suspension system through an active or semiactive suspension system. The authors of this paper have worked and cooperated with a team composed of members of Trenitalia SPA (main Italian railway company), Ital-certifer (an Italian R&D agency), and many Italian Universities (Universita di Firenze, Politecnico di Milano, Universita di Pisa, and Universita di Napoli) to the development of a prototype of an innovative railway pantograph for Italian high-speed lines. The authors have designed the layout of the control system (actuation system, sensors, drive and control algorithm, etc.). The proposed control strategy has been successfully calibrated with experimental tests. Testing procedures and experimental results are shown in order to demonstrate the feasibility of the proposed solution and performances achieved by the first Trenitalia prototype, the T2006 pantograph.

Freight wagons are usually equipped with the standard Union Internationale des Chemins de Fer pneumatic brake. On long trains, the propagation of the pneumatic signals along the pipe and different braking/loading conditions may produce delays and/or differences in the application of the braking effort along the train. This phenomenon may cause heavy longitudinal forces exchanged between wagons through buffers and draw gear. In particular, the workgroup n.6 (freight trains composition) of the Italcertifer committee has performed some preliminary studies concerning the application of LL braking operative conditions on freight wagons trains travelling on Italian lines. Partners have cooperated in this workgroup; however, in this paper, the attention is focused on methodologies and results concerning the contribution of University of Florence. The results of this activity, coordinated by RFI-CESIFER have been used to emanate the 20/07 rule of the RFI (‘Modifiche alla Prefazione Generale all'Orario di Servizio’) which modify the composition criterion rules of freight trains on the Italian Railways in order to introduce and discipline the application of the LL braking operative condition.