Electric rail and badgers

[Mothmig]

The rail that carries the electricity on the overground rail system is enough to kill you if you step on it I believe so why isn't the track littered with dead badgers and foxes and rabbits ? Or is it and we the passengers just can't see them?

[R1Geezer]

The current varies in the live rail, if the train is near then it's deadly if not them there's a good chance of survival.I also think those animals seem to know whats dangerous, I mean you don't see thousands of them on the roads either.I've seen the occasional fox and rabbit never a badger, so I'd imagine it's not that common for them to cross railway lines.

[Gromit]

The rails themselves only carry very low volts for track circuits which are used for the signaling. It will not kill you or animals. You are in more danger of slipping on them.

The high voltage is carried in the overhead lines. There are circumstances where the traction return is faulty or broken and the track rails then can have a higher charge.

[Hymie]

Both the above two answers are nonsense – the third rail in the UK is at 750Vdc, this voltage does not change as a train approaches and can certainly deliver enough current to kill an animal (including humans).

Soon after the third rail was installed, it was quite common for many animals to be found dead, due to contact with the lethal voltage. As time passed, it would appear that animals did indeed learn to keep away. Quite how they communicated this danger to one another is a mystery – perhaps it is natural selection, only those having an aversion to long straight pieces of metal, survive.

[Teddio]

Southern England uses a 750 Volt dc third rail system. The third rail is live at a potential difference of +750V dc. The two running rails are at zero Volts and act as a current return. For an animal to get an electric shock it would have to be in simultaneous contact with the live rail and an earth: the running rails or the ground would suffice. Would contact between the live rail and dry ballast provide a sufficiently good earth return to ensure a lethal current?
The East Coast Main Line uses a 25000 Volt ac overhead line system.

[heathfield]

Teddio asks if contact between the live rail and dry ballast could kill. A few years ago, I remember reading that a boy had been killed when he touched the live rail with a dandelion leaf he was holding. Whether the ballast was dry or wet at the time wasn't reported.

[Dodger666]

Don't you ever wonder why birds can perch on the National Grid power lines with voltages up to 400kV?

To be dangerous they would need to complete a circuit to enable current to flow. To do this they would have to touch an earth or a cable of a different phase on a three phase distribution system at the same time. It would need a very large bird to do this.

[Mothmig]

Thanks everyone - other research tells me that the third rail is only powered up in sections as the train approaches so not always lethal which may help. The natural selection theory seems to be the one, I read somewhere that the lack of squished hedgehogs on the roads these days was due to the running in-danger-hedgehog gene expressing itself over the curling-up gene. Would it work that fast i.e. in my life time?

My neighbour is a train driver . I'm going to ask him too.

Dodger666 surely they get tingley feet.

[New Judge]

I'd be interested to learn where your other research comes from, Mothmig, or the results of your chat with your train driver chum.

I have studied railways quite a bit and nowhere can I find that live rails are powered up only intermittently.

[Dodger666]

Quote: Dodger666 surely they get tingley feet.

Wouldn't know about that, but it must keep their feet warm in the winter

[Cathyhuns]

I am a railway engineer and both the dc third rail and ac overhead are live whether there's a train on the tracks or not. Both can be turned off but it would be very unusual to control the current so it turned on just before a train entered a section. What does happen is that when a train enters a section the current returns to earth through the running rails so you could say that the running rails are only fully live when there's a train in the section. At other times the running rails will carry residual currents so are less likely to harm you.

[Mothmig]

think that clears up the liveness once and for all, thanks Cathyhuns. But what about the dead animals are there any ? My belligerent friend down the office is not convinced yet.

[Mothmig]

Sorry it took a while but in case any of you are there, I spoke to my neighbour the train driver and he said the line up towards London is littered with the corpses of badgers, moreover he said what happens is that the badger touches the live rail, gets a belt off it, thinks its being attacked, so goes for it and bites the live rail thus wiping itself out by its aggressive behaviour. Silly old badger.