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Train crash at Chicago O'Hare Airport


roundhouse

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Always seems to be a lack of "dead man handles" here in the US.

Andy

 

Or not.

 

According to this story:

 

http://www.cnn.com/2014/03/27/us/chicago-ohare-train-derailment/

 

The NTSB said the train had an equivalent of a "dead man's pedal" and an additional end of the line emergency brake system which, for reasons unknown at this time, both failed to stop the train.

 

One of the reasons fewer railroads use a "dead man's pedal" is they aren't very effective and can be defeated with a small amount of effort.

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Or not.

 

According to this story:

 

http://www.cnn.com/2014/03/27/us/chicago-ohare-train-derailment/

 

The NTSB said the train had an equivalent of a "dead man's pedal" and an additional end of the line emergency brake system which, for reasons unknown at this time, both failed to stop the train.

 

One of the reasons fewer railroads use a "dead man's pedal" is they aren't very effective and can be defeated with a small amount of effort.

 

I'm only somewhat familiar with the controls that I've seen used on UK subway trains and suburban diesel units. But here's my understanding

 

The throttle is operated as a knob on a rotary arm, moving through an almost horizontal arc, on the slightly sloping top of the sitting engineers desk like dashboard. Movement range varies but 1 o'clock to 5 o'clock sounds about right, zero to full power. It's strongly spring loaded, so will return to zero if let go of. In addition, it is sprung strongly, slightly upwards at the knob end, much like an office stapler.

 

In operation the knob must be depressed to move the arm from the zero position and held depressed at all other speed settings. Letting the knob rise while the train is moving, for other than a short period of time, will automatically apply the brakes. 

 

The springing is such that if the operator falls unconcious forward on to of the control, the weight of the upper body is not sufficient to prevent the knob rising and the arm returning to zero. I doubt such a control would be practical for long haul US cross country trains, but for frequent stop rapid transit type, it's pretty effective.

 

Andy

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Interesting. The EMU's I work have deadman handles on the master controller and a deadman footswitch, as well as task-linked vigilance control. So even if you keel over dead and somehow don't activate the deadman then the VC will pulll you up fairly quickly.

 

At dead-end terminals you approach on a low-speed signal which has an intermediate train stop. If you don't reduce your speed - usually to 25kmh - the trip stays up and you lose the air. There are also fixed train stops well in advance of the buffers. I'd be interested to know what the signalling arrangements are in this instance, because as Keith says, there's no way you'd stop a train from that speed in 41 feet.

 

Cheers,

 

Mark.

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