Editing Dead man's switch (section)

====Vehicles====
Handle switches are still used on modern trams and trains. [[Pneumatic]]ally or electrically linked dead man's controls involve relatively simple modifications of the ''controller handle'', the device that regulates traction power. If pressure is not maintained on the controller, the train's emergency brakes are applied. Typically, the controller handle is a horizontal bar, rotated to apply the required power for the train. Attached to the bottom of the handle is a rod that when pushed down contacts a [[solenoid]] or switch inside the control housing. The handle springs up if pressure is removed, releasing the rod's contact with the internal switch, instantly cutting power and applying the brakes.

Though there are ways that this type of dead man's control could conceivably fail, in practice they have proven highly reliable. On some earlier equipment, pressure was not maintained on the entire controller, but on a large button protruding from the controller handle. This button also had to be pressed continuously, typically with the palm of the hand so that the button was flush with the top of the handle. Another method used, particularly with some lever-type controllers, which are rotated rather than pushed or pulled, requires that the handle on the lever be turned through 90 degrees and held in that position while the train is in operation. Some dead man's controls only work in the mid position and not with full pressure (see [[pilot valve]]).

In modern [[New York City Subway]] trains, for example, the dead man's switch is incorporated into the train's speed control. On the [[R142A (New York City Subway car)|R142A]] car, the train operator must continually hold the lever in place in order for the train to move.

An example of a passenger vehicle using a dead man's switch is on [[Tesla Inc|Tesla]] electric vehicles. When the driver has engaged the semi-autonomous driving system "Autopilot", they must keep their hands on the steering wheel. If the driver takes their hands off the steering wheel for more than 30 seconds, a loud alarm will sound inside the car to wake sleeping drivers; if the driver leaves their hands off for more than a minute, then the car will engage its hazard warning lights and bring the car to a stop. This is done because the Autopilot system is not capable of full-self driving, and requires that the driver be able to take over operation of the vehicle without warning, should the car encounter a problem it does not know how to solve. This system uses a torque sensor on the steering wheel of the vehicle: when a driver is simply holding the wheel, they are still applying a small amount of torque to the wheel, confirming for the car that the driver is being attentive; if the driver turns the wheel with more force, all vehicle controls are handed back to the driver immediately.<ref>{{Cite web |url=https://www.tesla.com/support/autopilot |title=Autopilot and Full Self-Driving Capability |date=February 13, 2019 |website=Tesla.com }}</ref><ref>{{cite web |url=https://fortune.com/2017/06/23/tesla-autopilot-technology-keep-drivers-alert/ | title=Tesla: Technology Helps to Keep Drivers Alert After Autopilot Crash |website=Fortune }}</ref><ref>{{Cite web |url=https://www.theverge.com/2018/5/14/17352814/elon-musk-tesla-autopilot-face-tracking-gm |title=Tesla Rejected More Advanced Driver Monitoring Features on Its Cars |first=Sean |last=O'Kane |date=May 14, 2018 |website=The Verge }}</ref>