Page:ATSB RO-2018-004 - Collision of passenger train A42 with buffer stop.pdf/26



This system supports driver alertness and is in place to ensure the driver is maintaining vigilance at the controls. The standard for train (driver) safety systems defines a vigilance control system as a 'system that will react by bringing a vehicle or train to a stand if an acknowledgment input is not received within a specified time increment. On conventional vehicles with an automatic brake, the vigilance system will bring the train to a stand by directly venting the brake pipe to atmosphere'.

All Sydney Trains passenger trains have onboard task-linked vigilance devices which are set up to warn the driver and apply an automatic brake application if there is no acknowledgement by the driver in the vigilance time cycle. The acknowledgement tasks include: pressing the vigilance button, applying the horn, operating the windscreen wiper, operating the power/brake control handle, operating the headlights/fog lights and also depressing the operator enable pedal. For each of these tasks there are parameters applied to the detection. For example, if the control input for the vigilance is the headlights or the foglights, it can only be used for one reset of the cycle then another type of input must be used.

The vigilance system is operational only at the active end of the train, so is only available for the driver and not the guard. It commences operation only when the power/brake control handle is moved out of the isolate position and when either the brake cylinder pressure is below 75% full service brake cylinder pressure or the speed is greater than 5 km/h.

The vigilance system has a 30-second cycle; if the driver does not perform one of the tasks within the cycle then the vigilance penalty sequence begins. Firstly, a warning light flashes on the control board in front of the driver and on the vigilance button itself, the driver is required to acknowledge the visible warning within 5 seconds or the sequence will progress to the next stage. Then, during the next 5-second period, a bell also sounds and the driver is required to acknowledge within the 5-second period or the sequence will progress to the automatic brake application. If no action is taken by the driver, an automatic brake application is initiated which cannot be released until 3 seconds after the train comes to a stand. Following this, within the next 30 seconds, the driver can release the automatic brake by pressing the vigilance button. In the event of the driver failing to press the vigilance button within 30 seconds of the reset indicator, a distress message will be sent via the train’s radio to train control and the train’s park brakes will be applied (Figure 10).