Objectives Under the Reproducible Braking Distance (RBD) program, the Knorr-Bremse Rail Vehicle Systems division is developing a set of pioneering braking technologies to support and complement the ongoing development and modernization of rail infrastructure. By improving vehicle braking performance in all environmental conditions, RBD aims to further enhance the capacity, punctuality and resilience of rail operations. To achieve this objective, the development team is integrating the new deceleration control system (DCC) with the improved wheel slide protection system (WheelGrip adapt), as well as an adhesion management (ADM) system that is now designed as a train-wide solution with situational adaptivity. The efforts of the RBD development team are currently focused on realizing the potential of the various technologies involved. As part of preparing them for series production, the team must quantify their benefits for rail operations and demonstrate how well they function in the field. Methodology Following a generic simulation by Knorr-Bremse and the IFB Institute of Rail Technology (IFB Institut für Bahntechnik GmbH) to gauge the potential of RBD in operating conditions, a more detailed quantification study was carried out in collaboration with rail industry consultants NEXTRAIL and VIA-Con using the example of a real-world rail network (the Hamburg S-Bahn). A sensitivity analysis was performed to quantify the relative benefits of different levels of RBD equipment. The DCC system’s functionality had already been validated by tests performed in the course of 2018; this was now followed by a long-term study in the form of a 12-month field test involving a DCC-equipped multiple unit serving on Poland’s passenger lines. The train drivers subsequently took part in a survey. Knorr-Bremse, Deutsche Bahn and DB Systemtechnik also validated two of the key RBD components, WheelGrip adapt and ADM. Results According to the Hamburg S-Bahn study, the combination of reduced technical train headway times (TTHT) and improved service quality/punctuality boosted the network’s nominal performance (capacity) by 9.5% on dry rails and 26% on wet rails; the latter is almost identical to the network’s nominal performance in dry conditions. On dry rails, RBD can reduce the sum total of uncompensated delays by 18% and improve 3-minute punctuality by one percentage point. On wet rails, RBD reduces the sum total of uncompensated delays by 57%, meaning that a level of punctuality similar to that on dry rails is now attainable. The sensitivity analysis quantified the benefits of RBD in a train fleet fitted with different levels of RBD equipment. The analysis shows, RBD equipment levels of around 50% or more make it possible to reduce secondary delays and achieve a service quality and level of punctuality comparable to those of fleets with the full (100%) complement of RBD equipment.. The 12-month field test focused on validating the DCC function. The function was 100% available over the entire period of the test. According to a standardized questionnaire completed by 36 drivers of the multiple-unit train involved in the trial, 98% of the drivers rated the train’s braking behavior with the DCC function as either “better” or “identical”.. Conclusion The set intervals at which trains follow one another are based on a very clear safety premise: Even in the most adverse conditions conceivable, the vehicles must always come to a safe standstill within a specified distance. Numerous studies have shown that Knorr-Bremse’s Reproducible Braking Distance (RBD) development program, which has now reached a very advanced stage, can significantly reduce thevariance in braking and stopping distances, thereby helping to improve the capacity, punctuality and resilience of rail operations. The first RBD functions have already been integrated into the first RBD-enabled CubeControl brake control system and subjected to comprehensive testing. By the end of this year, the full set of RBD features should be available to customers for their projects. What the paper offers: The latest findings from the RBD development program combine, for the first time, an analysis of field-tests with a simulation of the system’s benefits for rail operations. The unique aspect of this analysis is that it not only demonstrates improvements of braking performance in the field, but when combined with rail-network simulations and studies, also shows how the various functions developed under the RBD program result in demonstrable, quantifiable improvements in rail operations as a whole.
Mr. Christopher Lozano, Head of RBD Project Cluster, Knorr-Bremses SfS; Mr. Michael Kohl, Productmanagement Brake Systems, Knorr Bremse SfS GmbH