Editing Dead man's switch (section)

===Pedal===
[[File:SIFA-Pedal.jpg|thumb|Dead-man's vigilance device (here a pedal) on the cab car of a German InterCity train]]
A pedal can be used instead of a handle. While some pedal switches must simply be held down in order for the machine to function (this system is often found on amusement rides, where the operator is likely to remain in a standing position for a lengthy period of time while the ride is in motion), this method has some shortcomings. In the [[Waterfall train disaster]], south of Sydney, Australia, in 2003, the driver suddenly died of a heart attack, and his slumped body kept the pedal depressed.

There are some solutions to this issue that are now used in modern pedal systems. The pedal can have a vigilance function built in (a '''dead-man's vigilance device''', '''driver vigilance device''' or '''DVD'''),<ref>{{Cite web |url=https://www.rssb.co.uk/research-development-and-innovation/research-project-catalogue/t024 |title=Driver Vigilance Devices – Systems Review (T024) |website=RSSB.co.uk |archive-url=https://web.archive.org/web/20180804075725/https://www.rssb.co.uk/research-development-and-innovation/research-project-catalogue/t024 |archive-date=2018-08-04 |access-date=2018-08-04 }}</ref> where drivers must release and re-press the pedal in response to an audible signal. This prevents it from being defeated by the above circumstances and is a standard feature on most British DSD systems.<ref>{{cite web|url=http://locodocs.co.uk/brmanuals/DSD-33056-4-Issue1.htm |title=Locomotive Repair Books, Record Cards, Manuals and Driver's Handbooks |website=LocoDocs.co.uk |access-date=2013-11-15}}</ref> If the timer period is beginning to expire, a visual and audible warning is given. If the operator fails to acknowledge the warning, a [[penalty brake]] application results.

Some types of locomotive are fitted with a three-position pedal, which must normally be kept in the mid position. This lessens the likelihood of accidentally defeating it, although it may still be possible to deliberately do so. Adding a vigilance function to this type of pedal results in a very safe system. However, isolation devices are still provided in case of equipment failure, so a deliberate override is still possible. These isolation devices usually have tamper-evident seals fitted for that reason.