Testing for Authorization

Railway vehicles must undergo extensive authorization tests before they are put into service. This is especially true for railway vehicle brake systems. To allow for credible and robust statements, every single test out of an entire test campaign needs to be conducted repeatedly under invariable environmental conditions. These physical tests are conducted on dedicated test tracks. They are very costly, extensive, and time-consuming. It is assumed that simulation methodologies can be used to decrease these efforts. This is denoted as virtual testing, and requires a technically accepted process, a credible and trusted model, calibration of this model, and a minimum of available measurement data. Furthermore, the challenge is to guarantee the exact same safety levels that are achieved through real testing, and to provide a convincing argument, why simulation methodologies are suitable for that purpose.

Introduction of Virtual Testing

Renowned brake system supplier Knorr-Bremse cooperates with VIRTUAL VEHICLE to address these challenges. A dedicated simulation environment was created, that allows for simulation of different vehicle types. Furthermore, a process for virtual validation of railway vehicle braking systems was defined in the European Shift2Rail project PIVOT2. This process integrates into existing railway vehicle development processes of the EU Railway System. Existing measurement data are selected to calibrate and validate the model. This allows for virtual testing as a novel tool to be applied before and during vehicle development. This initiative is supported by international partners like Alstom (France), Deutsche Bahn (Germany), SNCF (France), and CP (Portugal).

Figure 1: Validation of the used model: Bold dashed curves predict a corridor of values and are produced by running the simulator with identified parameters. Measured data with the same initial velocity fall within this corridor.

VVC represents a significant change of the EU Railway System

The approach is based on existing standards that already recommend the application of simulation methodologies, (e.g., EN 14531, EN15595). But VVC represents a significant change of the EU Railway System. Therefore, also existing regulations are affected, like the technical specification for interoperability (TSI) locomotives and passenger rolling stock (LOC&PAS). For this reason, the mentioned partners also engage with relevant bodies, like the European Railway Agency (ERA) and NB-RAIL, where the described approach is under discussion.

Many methods, tools and processes of the railway industry are currently pushed by increasing levels of digitization. The application of simulation technologies in the railway sector is also driven by ongoing standardization activities of international consortia. One example thereof is the CEN working group 55, as part of TC256, SC3, currently preparing an overlay standard promoting the use of simulation in railway standards and regulations.

Innovating the Railway Business

It is expected that the VVC innovations will dramatically reduce the cost to put new vehicles into service. Furthermore, the time-to-operation will decrease, while current safety levels will be fully maintained. In the end it is expected that these innovations will lead to a more competitive railway engineering market, including more software tool vendors and simulation service providers, striving for higher quality railway vehicles and products.