The SIFA train function safety circuit

Summary

The SIFA is a paced secondary motor task, which is expected to monitor the train driver's ‘fitness for service’ on engines of the German Federal Railway. Disregard of the device leads to an emergency braking. As, in contrast to a true vigilance test, the SIFA cycles are characterized by paced and clearly supraliminal signals; we presumed that adequate operation of the device does not necessarily correspond to sustained attention of the driver. This study shows how the SIFA can be effectively tested under laboratory conditions. Our design allows the reduction of vigilance as evident from the EEG, and a controlled investigation of the possible connection between different modes of SIFA operation, physical load, and different levels of vigilance. Finally, some sample registrations show that phases of low vigilance do occur and do not prevent adequate operation of the device. It is suggested that SIFA-trained persons can operate the SIFA in phases of low vigilance because a specific central nervous arousal reaction enables them to raise their level of vigilance in synchronisation with the SIFA cycles to a degree that makes the successful performance of this task possible. A future report will provide a quantified analysis of the correlation between vigilance reduction and SIFA operation.