On trains different incidents lead to the activation of an emergency brake despite the fact that the present safety target might be different. Due to the application of the emergency brake the reaction of the train, in this case the deceleration is ideally the same. For example, the automatic train protection system which is related to the infrastructure is initiating a penalty brake using the emergency brake channel to ensure a safe stop before the potential hazard point. In some applications also a penalty brake is initiated to prevent damage from the braking equipment in case of severe malfunction. An emergency brake initiated by the driver is targeting to prevent hazards. An emergency brake initiated by the passenger alarm system is targeting to protect the passengers. This brief overview is indicating that different safety targets are treated in a common way. For some of these incidents highly reliable deceleration rates are necessary to ensure brake distances within the infrastructure demands. Other incidents require the highest possible deceleration independent of a reproducibility to avoid crashes. Actual trains achieve their minimum brake distance based on preset parameters. To achieve the shortest brake distance that is physically possible, the emergency brake would need to be parameterized based on the actual operational parameters observed.
Dr. Uwe Viereck, Stefan Plamper - Bombardier Transportation GmbH