Dead-man's vigilance device
Encyclopedia
A dead-man's vigilance device is a railroad safety device that operates in the case of incapacitation of the engineer
. It is a hybrid between a dead-man's switch and a vigilance control.
The main safety failing with the basic dead-man's control system is the possibility of the operating device being permanently held in position, either deliberately or accidentally. The dead-man's vigilance device was developed to detect this condition by requiring that the dead-man's device be released momentarily and re-applied at timed intervals.
Modern locomotive practice is to incorporate the Dead-man's and Vigilance functions under the control of the Alerter (US) or the Event recorder
. This enables more sophisticated monitoring of the driver's alertness. The vigilance control cycle time can then be speed dependent, varying inversely to train speed in order to reduce the distance the train may travel before a non-response is detected and acted upon.
In addition to the dead-man’s pedal/button, the reset signal can also be any one of a number of train handling control actions already monitored by the Event Recorder. These include a change of throttle position, brake or horn operation, all indications that the driver is actively controlling the train.
If the timer period is allowed to expire a visual and audible warning is given by the Alerter or similar warning device. If the operator fails to acknowledge the warning, a Penalty Brake application results.
Vigilance control is not foolproof and should not be taken to indicate that the driver is vigilant in the true sense of that word. This is because it does not measure driver alertness, merely requiring the robotic response of button pressing. Such responses can occur without conscious input by the driver – the driver could be effectively asleep
, drunk
, or otherwise unaware of his environment and still automatically respond to the device.
Railroad engineer
A railroad engineer, locomotive engineer, train operator, train driver or engine driver is a person who drives a train on a railroad...
. It is a hybrid between a dead-man's switch and a vigilance control.
The main safety failing with the basic dead-man's control system is the possibility of the operating device being permanently held in position, either deliberately or accidentally. The dead-man's vigilance device was developed to detect this condition by requiring that the dead-man's device be released momentarily and re-applied at timed intervals.
Modern locomotive practice is to incorporate the Dead-man's and Vigilance functions under the control of the Alerter (US) or the Event recorder
Event recorder
A Train event recorder is similar to the flight data recorder found on aircraft. It records data about the operation of train controls and performance in response to those controls and other train control systems.Data storage is provided by magnetic tape, battery-backed RAM and, most recently,...
. This enables more sophisticated monitoring of the driver's alertness. The vigilance control cycle time can then be speed dependent, varying inversely to train speed in order to reduce the distance the train may travel before a non-response is detected and acted upon.
In addition to the dead-man’s pedal/button, the reset signal can also be any one of a number of train handling control actions already monitored by the Event Recorder. These include a change of throttle position, brake or horn operation, all indications that the driver is actively controlling the train.
If the timer period is allowed to expire a visual and audible warning is given by the Alerter or similar warning device. If the operator fails to acknowledge the warning, a Penalty Brake application results.
Vigilance control is not foolproof and should not be taken to indicate that the driver is vigilant in the true sense of that word. This is because it does not measure driver alertness, merely requiring the robotic response of button pressing. Such responses can occur without conscious input by the driver – the driver could be effectively asleep
Sleepwalking
Sleepwalking, also known as somnambulism, is a sleep disorder belonging to the parasomnia family. Sleepwalkers arise from the slow wave sleep stage in a state of low consciousness and perform activities that are usually performed during a state of full consciousness...
, drunk
Drunkenness
Alcohol intoxication is a physiological state that occurs when a person has a high level of ethanol in his or her blood....
, or otherwise unaware of his environment and still automatically respond to the device.
Accidents due to insufficient vigilance control
- Beresfield rail disasterBeresfield rail disasterIn the Beresfield rail accident of 23 October 1997, a coal train passed a red signal and ploughed into the rear of another coal train, causing a collision and derailment that blocked all four tracks...
- Violet Town railway disasterViolet Town railway disasterThe Violet Town rail accident, also known as the Southern Aurora disaster, was a railway accident that occurred on 7 February 1969 near the McDiarmids Road crossing, approximately 1 km south of Violet Town, Victoria, Australia.-Overview:...
- Hinton train collisionHinton train collisionThe Hinton train collision was a railway accident that occurred on February 8, 1986. Twenty-three people were killed in a collision between a Canadian National Railway freight train and a Via Rail passenger train. It was the most lethal Canadian rail disaster since the Dugald accident of 1947...
- NTSB accident report