Investigations of Degraded Adhesion Conditions and Interrelated Methods for Improving Braking Performance using the Advanced TrainLab (aTL)

Abstract

The article describes the results of on-train tests performed by Knorr-Bremse and DB Systemtechnik within the Shift2Rail PIVOT2 technology initiative under the HORIZON 2020 European Research Framework Programme. The tests aimed first, to carry out an in-depth investigation of degraded wheel/rail adhesion conditions, and second, to validate the effectiveness of technical solutions to optimally master such conditions. The solutions are especially important for later use with ATO (Automatic Train Operation) at Grade of Automation (GoA) level 3 and 4, meaning driverless/ unattended train operation, to avoid restrictions that would otherwise reduce rail system performance. Performed in spring 2022 aboard the DB “advanced TrainLab” (aTL), the tests concentrated on two solutions: WheelGrip adapt (a WSP function), and a train-wide Adhesion Management (ADM) function using sanding systems. The tests demonstrated the reliability of the adaptive response of the new WSP towards different adhesion conditions maintaining the same braking performance in regular low adhesion conditions (“UIC”) and improved braking performance in extremely low adhesion conditions. The advanced train-wide ADM was able to achieve even shorter stopping distances. With the support of the Vienna University of Technology (TU Wien), the study also investigated the behavior of magnetic track brakes (MTBs) and their conditioning effects, concluding that MTBs not only provide additional braking force, but also improve the performance of other brakes acting on downstream wheelsets. However, the effect differs depending on the third-body layer, achieving better results on paper-based versus oil-based contamination. The collected data will be used by Knorr-Bremse to design further solutions, and by DB Systemtechnik to produce a mathematical model to subsequently configure a WSP test rig for performing enhanced certification tests.