Schoolgirl crosses the tracks at Latimer Road station.

[Phil.]

The choice of either an official sanction or standing up in her school hall in front of her peers and explaining her reasoning for being so incredibly stupid, with BTP present to issue some rather harsh follow-up advice.

The idea that a teenager doesn't know that strolling across a railway line is dangerous is a deeply outdated viewpoint, I'm afraid. They do it because they think they're above the rules, not because they don't think it's wrong.

I did mention in an earlier thread about something else that the English are anarchic by nature.

 

[70014IronDuke]

The choice of either an official sanction or standing up in her school hall in front of her peers and explaining her reasoning for being so incredibly stupid, with BTP present to issue some rather harsh follow-up advice.

The idea that a teenager doesn't know that strolling across a railway line is dangerous is a deeply outdated viewpoint, I'm afraid. They do it because they think they're above the rules, not because they don't think it's wrong.

I'm sure you will correct me if I am wrong, but I'd bet you have absolutely no idea what this teenager thinks or does not think about her action(s) - bar your own prejudice.

What seems obvious to you, or me, or many in here regarding railways will be wonderland to many kids. Let's not forget many people seem to believe trains have a 'steering wheel'. If their parents spend their days reading internet tittle-tattle, and the kinds themselves spend half their waking lives listening to I-tunes, do you think they understand underground trains are powered from dangerous, live rails? Some, of course, will 'get it' one way or another - others will go through life totally oblivious - it could be perpetual motion for all they care.
--- old post above --- --- new post below ---

I did mention in an earlier thread about something else that the English are anarchic by nature.

I suspect you have never experienced driving in the likes of Afghanistan or Cario, because if you had, you would not make such a deduction.

The English (British) are unbelievably law-abiding compared to such cultures.

 

[Whistler40145]

I'm shaking my head in disbelief, first of all, it shows either how stupid or foolhardy the teen is, that and the fact that there's now a minimal amount of staff at stations, so I'm not at all surprised it doesn't happen more often.

 

[Peter Mugridge]

The choice of either an official sanction or standing up in her school hall in front of her peers and explaining her reasoning for being so incredibly stupid, with BTP present to issue some rather harsh follow-up advice.

When I was at school, this was the favoured way of dealing with any serious misdemeanour; assuming the offender had not been suspended or expelled they would be stood on stage during assembly while the whole school would hear the Principal or Deputy Principal explain what had been done.

If more schools did this today then people might think a bit more and behave a bit better.

 

[Kite159]

I'm shaking my head in disbelief, first of all, it shows either how stupid or foolhardy the teen is, that and the fact that there's now a minimal amount of staff at stations, so I'm not at all surprised it doesn't happen more often.

Even if you have staff on the platforms she still probably would have done it, and apart from the staff shouting at her what else would have have done (bar pressing an emergency button to shut off the power if such thing exists at that station).

 

[SpacePhoenix]

Maybe in areas where they no longer go round schools teaching them about how dangerous the railways can be, that they shouldn't trespass, etc they should start going round schools again.

 

[Tubeboy]

I had a similar situation at work a few months ago. Two teenage girls larking about, they were on opposite platforms. One told the other to throw her hat to her over the track. Thankfully I was doing a station check at the time and saw the whole thing. Hat lands on track. One of the idiots then decides to jump onto the track. A quick bellow from me, soon stops that plan. On the tube we have what's called a track retrieval device, a long rod with sticky pads on the end to pick up items dropped onto the tracks. To use this, you first call the controller to ask for permission and use a train as protection. I knew as soon as my back had turned, the idiot would have attempted to jump down onto the track again. So I brought her to my office to fetch the TRD and arrange protection. Whilst doing this I said to her that she could have been killed. She didn't have a clue what I was talking about, did not have a clue that the train runs on electricity, and that a 160 ton tube train will squash you to sausage meat. Complete plum.

Prior to all the staff cuts, I would have had two fellow staff on duty with me at the time, now I'm on my own. So it's a lot harder to notice these things.

 

[richieb1971]

From the pic it looks as if she made an educated guess not to touch the rails.

Could easily have gone the other way though. I did this at Hither Green depot in 1981 with the assistance of a British railway employee. So it makes me wonder how dangerous it is. I saw a NR guy kicking the electrified rail at Eastleigh station a few years ago. So I am a bit confused to the danger levels presented by the electrified rail. Not that I would dream of playing around to find out.

 

[LU_timetabler]

I had a similar situation at work a few months ago. Two teenage girls larking about, they were on opposite platforms. One told the other to throw her hat to her over the track. Thankfully I was doing a station check at the time and saw the whole thing. Hat lands on track. One of the idiots then decides to jump onto the track. A quick bellow from me, soon stops that plan. On the tube we have what's called a track retrieval device, a long rod with sticky pads on the end to pick up items dropped onto the tracks. To use this, you first call the controller to ask for permission and use a train as protection. I knew as soon as my back had turned, the idiot would have attempted to jump down onto the track again. So I brought her to my office to fetch the TRD and arrange protection. Whilst doing this I said to her that she could have been killed. She didn't have a clue what I was talking about, did not have a clue that the train runs on electricity, and that a 160 ton tube train will squash you to sausage meat. Complete plum.

Prior to all the staff cuts, I would have had two fellow staff on duty with me at the time, now I'm on my own. So it's a lot harder to notice these things.

Good catch, and good job, but how stupid are these girls not to know that trains run on electricity in the rails, I'd have thought that was obvious! And more to the point what were they doing in Year 7 science when Electricity and Electrical Safety is taught, or maybe their under-trained teacher missed that little bit of interest out. In my previous employ as a Physics teacher, I can assure you, that always went in!! Bring back the compulsory screening of a short railway safety video.

 

[BestWestern]

From the pic it looks as if she made an educated guess not to touch the rails.

Could easily have gone the other way though. I did this at Hither Green depot in 1981 with the assistance of a British railway employee. So it makes me wonder how dangerous it is. I saw a NR guy kicking the electrified rail at Eastleigh station a few years ago. So I am a bit confused to the danger levels presented by the electrified rail. Not that I would dream of playing around to find out.

The juice rail will quite happily do you serious damage somewhere on the burned/maimed/well cooked scale. This is less likely if you don't come into contact with it proper; i.e. whacking it with decently insulated boots, etc. A supposedly common experience of the old schoolers on the Southern was to be whacked on the back of the neck by the current when crossing the line in heavy rain and wearing old fashioned long, waterproof, soaking wet overcoats.

If you happen to be a teenage girl wearing school shoes and you end up landing flat on your face on it however, the experience is likely to be somewhat more severe.

 

[Phil.]

The juice rail will quite happily do you serious damage somewhere on the burned/maimed/well cooked scale. This is less likely if you don't come into contact with it proper; i.e. whacking it with decently insulated boots, etc. A supposedly common experience of the old schoolers on the Southern was to be whacked on the back of the neck by the current when crossing the line in heavy rain and wearing old fashioned long, waterproof, soaking wet overcoats.

If you happen to be a teenage girl wearing school shoes and you end up landing flat on your face on it however, the experience is likely to be somewhat more severe.

The wet overcoat is an urban myth. The longest overcoat comes half way down the calf, most are a couple of inches below the knee. To come into contact with the juice rail a coat would have to be ankle length.

 

[MikeWh]

The wet overcoat is an urban myth. The longest overcoat comes half way down the calf, most are a couple of inches below the knee. To come into contact with the juice rail a coat would have to be ankle length.

I think the key element was heavy rain which might bridge a gap, particularly if the coat was also dripping. I remember as a young boy (45+ years ago) being allowed to 'help' staff at my local station. One thing was emptying a bucket over the platform edge which was always accompanied by a "don't tip it directly onto the live rail" instruction.

 

[philthetube]

I think the key element was heavy rain which might bridge a gap, particularly if the coat was also dripping. I remember as a young boy (45+ years ago) being allowed to 'help' staff at my local station. One thing was emptying a bucket over the platform edge which was always accompanied by a "don't tip it directly onto the live rail" instruction.

I don't think a rail carrying 430v dc would jump to a coat, there are far more options closer that that for it to jump eg running rails.

 

[Phil.]

I think the key element was heavy rain which might bridge a gap, particularly if the coat was also dripping. I remember as a young boy (45+ years ago) being allowed to 'help' staff at my local station. One thing was emptying a bucket over the platform edge which was always accompanied by a "don't tip it directly onto the live rail" instruction.

DC doesn't "jump" like AC.

 

[Nym]

DC doesn't "jump" like AC.

Damn, all them arc gaps and requirements for separation aren't needed, I can make all the kit much smaller...(!)

Slightly on topic, I'm wondering if anyone on here has been shocked with AC and/or DC? I can assure you it does rather much hurt...

 

[BestWestern]

Damn, all them arc gaps and requirements for separation aren't needed, I can make all the kit much smaller...(!)

Slightly on topic, I'm wondering if anyone on here has been shocked with AC and/or DC? I can assure you it does rather much hurt...

Only by the usual pratting about with batteries in a technology class in school. Our teacher was the main culrpit, had us all holding hands and linked us up to a battery. Not quite 25,000v thankfully, but it's interesting that even at very low voltage the sensation is uncomfortable; one can easily imagine how it would be very deeply unpleasant indeed at full chat!

As a (slightly gruesome) matter of interest, is there a consensus on the 'experience' of coming into contact with very high voltage, i.e. OHLE? Is it considered that a casualty has a conscious feeling, or is the shock effect such that one would likely be rendered completely incapacitated instantly? I gather survivors to provide an explanation are few and far between...

 

[DaleCooper]

DC doesn't "jump" like AC.

Doesn't it? Do you have a source for that?

Damn, all them arc gaps and requirements for separation aren't needed, I can make all the kit much smaller...(!)

Slightly on topic, I'm wondering if anyone on here has been shocked with AC and/or DC? I can assure you it does rather much hurt...

I had a 240VAC shock a long time ago, as far as I remember it was painful but short lived as I snatched my hand away pretty quickly. I think I must have touched both terminals with one hand so the current didn't pass through my body just from one finger to another.

 

[rebmcr]

I've had 240v AC through one hand as well, it was an unpleasant jolt, as if I was being hit with an object but on every part of my arm simultaneously. Yanked it back, and my whole arm was numb and tingling for about an hour.

My sampling of DC has been limited to a 9v battery on my tongue, and I'm very happy to keep it that way!

 

[Nym]

Somone who lost a hand if I remember correct y near Milton Keynes on an OHLE feeder was considered lucky it was only his hand.

 

[philthetube]

The big difference between DC and AC is that AC throws you off so you do not remain in contact with the source, DC holds on to you.

The reason for big rail gaps on the underground is to prevent trains bridging sections and so livening up areas where there should be no current.

 

[philthetube]

Doesn't it? Do you have a source for that

Not a source as such but watch P way stride across 3rd rail, or even walk on it, they are not allowed within 10 feet of overhead lines, also look how close the 3rd rail is to the running lines.

http://www.brighthubengineering.com/power-plants/89792-ac-and-dc-shock-comparison/

However DC current will make a single continuous contraction of the muscles compared to AC current, which will make a series of contractions depending on the frequency it is supplied at. In terms of fatalities, both kill but more milliamps are required of DC current than AC current at the same voltage.
(this is an extract from above link but cannot manage to get it in blue box).

 

[DaleCooper]

Not a source as such but watch P way stride across 3rd rail, or even walk on it, they are not allowed within 10 feet of overhead lines, also look how close the 3rd rail is to the running lines.

The important difference between 3rd rail systems and overhead lines is not whether they're AC or DC it's the voltage, 3rd rail systems use 650/750V whereas overhead lines are at 25kV. As a first approximation the safe distance from 25kV is going to be about 30 times greater than that for 750V; 3 metres (10 ft) as against 10cm (4"), although this depends on many other factors. As for walking on the 3rd rail; that's possible if there's no path to ground, that's why birds can perch on high voltage wires.

http://www.brighthubengineering.com/power-plants/89792-ac-and-dc-shock-comparison/

However DC current will make a single continuous contraction of the muscles compared to AC current, which will make a series of contractions depending on the frequency it is supplied at. In terms of fatalities, both kill but more milliamps are required of DC current than AC current at the same voltage.
(this is an extract from above link but cannot manage to get it in blue box).

That reference has no relevance to the ability of the voltage to jump across a gap and really the difference in effect of AC and DC are, for most purposes, academic. They are both dangerous so keep off.

 

[philthetube]

Doesn't it? Do you have a source for that?



I had a 240VAC shock a long time ago, as far as I remember it was painful but short lived as I snatched my hand away pretty quickly. I think I must have touched both terminals with one hand so the current didn't pass through my body just from one finger to another.

The important difference between 3rd rail systems and overhead lines is not whether they're AC or DC it's the voltage, 3rd rail systems use 650/750V whereas overhead lines are at 25kV. As a first approximation the safe distance from 25kV is going to be about 30 times greater than that for 750V; 3 metres (10 ft) as against 10cm (4"), although this depends on many other factors. As for walking on the 3rd rail; that's possible if there's no path to ground, that's why birds can perch on high voltage wires.



That reference has no relevance to the ability of the voltage to jump across a gap and really the difference in effect of AC and DC are, for most purposes, academic. They are both dangerous so keep off.

The reference was relating to DC causing muscles to remain tensed and so holding on to the power source.

 

[BestWestern]

So hypothetically then, if one was to stand on the juice with your average pair of heavy duty, rubber soled safety boots on, what's the likely outcome? A lucky escape, or a melted boot and a fried leg?

 

[DaleCooper]

So hypothetically then, if one was to stand on the juice with your average pair of heavy duty, rubber soled safety boots on, what's the likely outcome? A lucky escape, or a melted boot and a fried leg?

No effect as long as you don't complete the circuit. If you do complete the circuit by placing one foot on the live rail and the other on the ground or the running rail then ordinary rubber soles probably won't protect you as rubber usually contains a lot of carbon black which is conductive, non-conductive boots are available.

 

[Nym]

The big difference between DC and AC is that AC throws you off so you do not remain in contact with the source, DC holds on to you.

The reason for big rail gaps on the underground is to prevent trains bridging sections and so livening up areas where there should be no current.

The reference was relating to DC causing muscles to remain tensed and so holding on to the power source.

That would be a gross over-simplification, you would need to consider the circumstance each time, since repeated spasm caused by AC could be more of a problem in some shock scenarios, where the DC spasm can cause you to be 'held on', similarly it can throw you off, the same is true for AC.

Simply saying DC is more dangerous than AC because it holds on where AC doesn't holds very little truth.

I can say for a fact that having been shocked by both AC and DC at varying voltages, the opposite has usually been true, when receiving an LV AC shock, it has been difficult to pull away from, where as an LV DC shock caused an immediate spasm, tensing the muscle and causing it to pull away from the live terminals.

It all depends on which muscle contracts, and where you're in contact with it, and the state of the muscles when you come into contact.

Either way, my advice would be to simply avoid coming into contact with anything live at all. Aside from some very special circumstances (battery connections being one), it is never a requirement to work live, and indeed there are the electricity at work regulations of the health and safety act that consider this specifically.

And on the topic of bridging,

Bridging has bigger issues than livening up a dead section, the issue arising from the likelyhood of a current sink being present in the dead section.

Lets say that a CRID (Current Rail Indicator Device) and SCD (Short Circuiting Device) have been placed down at either end of the dead section, and a train bridges into it, a full fault current will be drawn down from the local sub station, assuming that it is a double end fed section of course, now if we're near the sub station, this will be of an order of around 10,000A, with the 935mm^2 cable from the TxR (Transformer-Rectifier) feeding the track, lets assume new-ish CCR/ULLCR (Composite / Ultra Low Loss Conductor Rail), this would cause negligible loss compared with the next part of the circuit.

Shoegear drop leads are usually realised by 95mm^2 cable, or 150mm^2 on newer stocks, lets assume an older stock.

This will have 10 times the volt drop compared with the other feeders, the resistance of this being around 0.2mOhm/m. With around 20m of this cable between the 3 way box and the main fuse box, there's 4mOhm per pole of the circuit, so lets now come to our power calculation of I^2.R, 10,000A, squared, multiplied by 4mOhm, so there will be 400kW of power to disipate within the conduits in which this cabling is held. Now consider that the protective devices can take up to 5 seconds to trip, and can be auto re-closed multiple times, the insulation is very likely to have failed and case a flashover on the live voltage circuits of said train.