CTA 'L' Derailments and the Live 3rd Rail

[Railwaymodeler]

After being at my dad's house and he and I working on our Lionel railroad in his basement, I got to wondering:

Lionel trains use a center third rail for 'hot' current. the concept is like the outside 3rd rail on the CTA 'L'.

When a Lionel engine or car derails, usually the metal wheels and axles will short the running rails (Which are ground) with the hot rail. Everything screeches to a halt.

With the occasional derailment on the CTA, what happens? I would assume that there are safeguards to keep from zapping passengers if the derailed train touches the 3rd rail. But, what happens if the train touches the third rail and the running rails simultaneously? I would imagine it would NOT be pretty.

Does the whole block the train is in shut down? I don't imagine that they would have the whole thing NOT divided electrically. Otherwise a derailment would shut down any train on any connected track!

[Busjack]

I assume that what you are asking is what happens if the wheel itself shorts the hot rail circuit, rather than the normal situation of the electric pickup having contact with the third rail and grounded by a running rail. I don't have an answer, but I assume that the entire truck is insulated from the car body.

Considering that the cab signal systems notes the presence of a train by the wheels shorting out the running rail carrying the radio frequency signal, I suppose that bad things could happen to that if all the sudden it was hit with 600 volts.

As far as cutting out the whole block, it is always announced, in the case of an accident, that power was cut from the block and trains can't proceed until the wreck is cleared. Thus, they intentionally cut power to the portion of the line, anyway.

I suppose I shouldn't have said as much as I did, and should have deferred to an electrical engineer. Where is George Krambles (who started as an electric system controller on the L) when you need him?

[Railwaymodeler]

@BusJack,

I kind of figured that the carbody is insulated from the trucks. So far as I remember reading, there was a lot of fear of steel 'L' cars in the prewar days, due to fear of electrocution.

What I am specifically wondering, is say the car truck touches the third rail and the running rails simultaneously. A single axle skipping the rail would easily cause this. Isn't, at 600 volts, there a big risk of fire from the sparking?

Early model trains used an outside running rail, back in the 1930s. Walt Disney had such a setup himeself. I happen to have a book published in 1941 all about the virtues of two rail operation.

I think the reason the CTA and other electric lines opt for the third rail is partially a polarity issue. A reversing loop causes a short circuit without fancy electronics controlling polarity.

Mostly this musing is drawn off experience with electric model trains, so I don't know how relevent it all is to 1:1 scale trains.