3rd Rail Legislation

[johnnychips]

They went and checked it out using an electric fence on Brainiac: Science Abuse once, but I forget what the conclusion was.

http://chicago.cbslocal.com/2012/04/23/man-dies-after-peeing-on-l-tracks-in-evanston/

It was on Mythbusters, and they found it impossible unless the rail was very close and the water flow was unrealistically large. In the above example, he could have fell on the rail.

However, I did find this:

http://www.dailymail.co.uk/news/art...urinating-750-volt-electric-railway-line.html

but there doesn't seem to be a witness.

 

[Mojo]

We often had "foreign drivers" bring a loco down to the Southern. When they got out and started crossing the track, they were totally paranoid about the 3rd rail - they'd step over, lifting their legs as high as possible, even where kick-boards were installed - was so funny to see.

Fact is, if you brush against the side of the 3rd rail, you'll get a kick up the @r5e. It's unlikely to kill you just from that. If you fall flat on it then you're likely to fry. It will burn, it might kill, might not. Once you touch the live rail, you discharge the current to earth and trip the circuit breakers in the Electrical Control Centre - the current goes off.

Slightly off-topic but do Toc staff who work on lines with electrified rails wear any insulating shoes? I only ask as I know on the Underground that staff wear shoes that would enable the wearer to stand on the juice rail and not get a shock. Admittedly the voltages on the Underground are quite a bit lower than on Network Rail.

 

[Class377/5]

No. It's like I said in the first post, people keep saying it's prohibited / illegal etc and I was just trying to find out if it really is prohibited, or if it's a case of people on various forums talking utter nonsense. It seems the latter is true.

I don't think you understand how it works. All new works require a case for doing so. In this you look at the implementation of the technology in this case wires vs 3rd rail.

Fact is trains fail and you need to be prepared to evacuate people when when starting from fresh it makes more sense to use OHLE rather than 3rd rail as passengers risk levels are supposed to be minimised where possible. If there is no need for adding power where passengers can touch it why do so? Infill is used as its extending what's already around it. Uckfield is a good example where services using any newly laid 3rd rail wouldn't ever see OHLE so the higher risk factor is used acceptable as it exists on part of the jounery anyway.

This is the thinking behind using OHLE rather than 3rd rail. That's without fact OHLE requires less sub stations so it cheaper to implement and makes track work simpler.

It's a while range of issues but it's clearly not banned. Just not preferred in planning.

 

[W230]

It's been a while since I was employed on the Southern and I can't remember the exact process, but ECC staff will end up waiting one minute before resetting the breakers - this gives time for staff to put a short circuit bar down and/or put out an emergency call - when ECC staff reset the breaker again, if current stays on, they leave it on (line will be clear) - if it trips again, they'll wait 3 minutes (I think) - and if it trips again, it doesn't get reset until someone has checked things out properly (track walk etc) (a current railway employee might be able to confirm / correct this)

I'd always thought that auto-reclosers were used on the 3rd rail but maybe it's only on OLE? The idea behind them being that they re-energise the circuit once tripped to 'blow' the fault clear.

I think the H&S argument though is not the full truth behind the lack of 3rd rail projects. I think it's far more likely, as already mentioned, that it is old technology, has high power loss and is just simply not as efficient as OLE. Certainly (well, at present) the AC traction motor seems to be the more efficient way to power the units. I'm not disagreeing that the 3rd rail is potentially less safe than OLE but I think lots of things try and hide under the umbrella of H&S law when it's not actually the case and that this talk with the 3rd rail is one of them! It's more simply that it's old technology.

 

[Mutant Lemming]

Slightly off-topic but do Toc staff who work on lines with electrified rails wear any insulating shoes? I only ask as I know on the Underground that staff wear shoes that would enable the wearer to stand on the juice rail and not get a shock. Admittedly the voltages on the Underground are quite a bit lower than on Network Rail.

You could walk barefoot on a juice rail (have seen it done) as long as you don't earth it.

It actually has me wondering if conductor rail electrification is actually safer for the general public. Have come across numerous incidences of people coming to no great harm after coming in to contact with a conductor rail yet most instances where someone comes in to contact with OHLE death usually ensues. Admittedly most who come in to contact with OHLE are either employees or people up to no good but am wondering how many people are electrocuted by conductor rail as opposed to OHLE in an average year.

 

[EMU_Man]

I think the answer to your question lies in ....

that's speculation, not fact

the DLR was allowed to use 3rd rail, but protected 3rd rail

the DLR uses "covered" 3rd rail ... some 3rd rail systems around the world use side or bottom contact not for "safety", but because ice forms on the top surface of 3rd rails in the winter ... ice is not a good conductor of electricity so shoe gear can ride on the surface of the ice and the train gets no power .... although if the ice is not constant (solid), there will be partial contact causing arcing ... this arcing can discharge the current to earth because the arc can reach across to the bogie or running rail ... current discharge will then trip the breakers and cause loss of power supply .... arcing can also cause serious damage to shoe gear

but that's all irrelevant to the original question
--- old post above --- --- new post below ---

It's not a case of "utter nonsense"- it's more a case of "poor understanding" or "ppoor summary". It is effectively banned (or near enough) as a result of the enactment of responsibilites under legislation- but there is no specific law saying "though shalt not build a 3rd rail railway". Saying that it is "prohbited" or even "illegal" is clumsy shorthand- though no doubt many people believe it to really be the case.

It's not as clear cut as you seem to want it to be.

i think it IS clear cut .... people on this forum and other forums "suggest" that further use of 3rd rail is "prohibited" .... which is quite simply "utter nonsense"
--- old post above --- --- new post below ---

I was under the impression that urine as a constant flow replicates rainfall by being in droplet form and does not conduct electricity.

correct .... ish ....
urine forms droplets like rain .... DC needs a continuous circuit in order to flow .... it can't jump like AC does .... so urination onto DC 3rd rail won't cause electric shock (although if someone is determined to get close enough, i'm sure they can do it)

there were rules for running trains through flood water .... i can't remember them exactly now, but i THINK that (in the long distant past) we were allowed to run through flood water that was touching the live rail but not covering it (water not being a good conductor of DC) .... and i think the rules changed after a couple of incidents (the DMMU that fell in the river in wales springs to mind) .... this was many many years ago though .....
--- old post above --- --- new post below ---

Slightly off-topic but do Toc staff who work on lines with electrified rails wear any insulating shoes? I only ask as I know on the Underground that staff wear shoes that would enable the wearer to stand on the juice rail and not get a shock. Admittedly the voltages on the Underground are quite a bit lower than on Network Rail.

I don't know what uniform is issued these days, but back in BR days, uniform was the same up and down the country .... we bought our own shoes, just normal shoes that we could get anywhere .... I don't remember any railway issue shoes way back then, although I know there were railway issue shoes more recently .... track workers wore steel toecapped boots .... not sure if they were railway issue or not ....

but the bottom line is, no, the shoes we wore were nothing special .... we didn't have to wear special shoes because of the 3rd rail or anything like that ....

the ONLY uniform thing i remember that was different on 3rd rail lines to elsewhere was that the long overcoats (below the knee) were not issued on the southern (because they could touch the live rail) .... we had shorter ones ....

 

[Eagle]

Relating to DC vs OHE. Which uses the most electricity to operate? I know AC is expressed as the route mean square value while DC is a constant value so the values aren't a direct comparison.

What do you mean by "most electricity"? Most energy, most power, most current? (And I assume you mean per mile as well, and of course it probably depends on how often trains pass it and how much current they draw.)

 

[EMU_Man]

I don't think you understand how it works. .... Fact is trains fail and you need to be prepared to evacuate people when when starting from fresh it makes more sense to use OHLE rather than 3rd rail as passengers risk levels are supposed to be minimised where possible.

This shows you have a very clear lack of understanding of railways ....

Train crew are trained for evacuation of trains in emergencies (and evacuation will only be done in an emergency, not because of a "failed train") .... there are Rules and Regulations that cover detraining of passengers and procedures to follow .... those procedures will include current isolation (ideally requesting it via signaller and ECC) and always using the short circuit bar to ensure the current cannot be switched back on .... the procedures will also include things like stopping all trains on other running lines, telling passengers how to alight safely down the ladder, how to walk on the track (step ballast to ballast, do not walk on sleepers or rails as they may be slippery), walk in the cess, etc etc etc etc etc .... the driver will always put the short circuit bar down, so the live rail is not live (but always treat it as if it IS live at all times) .... this sort of thing is drummed into train crews during their training and beyond ....

and if you're working under the wires, training includes the same things, but "beware of the overhead wires, treat them as live at all times" ....

next time you're at the station taking down numbers, take a closer look at the trains .... you'll see little yellow signs with a black lightning bolt .... they say something like "Danger: Overhead Wires" .... here's some i found for you, check the offside cab windows .... http://www.therailwaycentre.com/Pages EMU/Recognition EMU/IllusEMU_317.html

i haven't seen any yet saying "Danger: Live Rail" ....

 

[Eagle]

i haven't seen any yet saying "Danger: Live Rail" ....

I have. On pretty much every train that operates in the Southern region (including things like XC Voyagers and FGW 158s).

 

[EMU_Man]

I'd always thought that auto-reclosers were used on the 3rd rail but maybe it's only on OLE? The idea behind them being that they re-energise the circuit once tripped to 'blow' the fault clear.

To be honest, I don't know if they use auto-reclosers on 3rd rail lines these days .... it was always a manual reset back in the old days .... a manual reset was simply "pushing a button", nothing major ....

I think the H&S argument though is not the full truth behind the lack of 3rd rail projects. I think it's far more likely, as already mentioned, that it is old technology, has high power loss and is just simply not as efficient as OLE.

25kv AC allows more trains to draw more power than can be done via ~750v DC ..... there are considerably more trains running now than when the southern was first electrified, and the trains are longer and require more power .... these are the reasons why 25kv AC is preferred over 750v DC .... nothing whatsoever to do with safety ...

however, 750v DC is still perfectly capable of powering large numbers of trains .... look at the number of running lines into London Bridge etc .... it's just a case of providing sufficient power from the substations ....

some areas were electrified more recently (think eastleigh to fareham) using aluminium 3rd rail as this conducts electricity more efficiently, allowing greater distance between substations, therefore cheaper to set up .... however, the greater the distance between substations, the greater the voltage drop .... this creates restrictions on the amount of power that can be drawn (and therefore the number of trains that can run through that section at any one time) .... so installing 3rd rail "on the cheap" may have caused problems in some areas .... and other areas now have considerably more trains than the original substations were designed for .... in both cases, upgrading substations will cure the problems .... the technology exists, it's been around for decades .... it's just a case of replacing the gubbins (transformers?!?!) with more powerful ones .... and this has been done in numerous substations already ....

Certainly (well, at present) the AC traction motor seems to be the more efficient way to power the units.

i think most 3rd rail units on the southern use AC motors now .... Networkers certainly do, so fairly sure the newer swt/southern units do too .... 455/442 use DC motors

 

[John55]

that's speculation, not fact


there were rules for running trains through flood water .... i can't remember them exactly now, but i THINK that (in the long distant past) we were allowed to run through flood water that was touching the live rail but not covering it (water not being a good conductor of DC) .... and i think the rules changed after a couple of incidents (the DMMU that fell in the river in wales springs to mind) .... this was many many years ago though .....
--- old post above --- --- new post below ---


I don't know what uniform is issued these days, but back in BR days, uniform was the same up and down the country .... we bought our own shoes, just normal shoes that we could get anywhere .... I don't remember any railway issue shoes way back then, although I know there were railway issue shoes more recently .... track workers wore steel toecapped boots .... not sure if they were railway issue or not ....

but the bottom line is, no, the shoes we wore were nothing special .... we didn't have to wear special shoes because of the 3rd rail or anything like that ....

the ONLY uniform thing i remember that was different on 3rd rail lines to elsewhere was that the long overcoats (below the knee) were not issued on the southern (because they could touch the live rail) .... we had shorter ones ....

My comments about the Pringle and Weir Committees are true and do explain the situation with respect to the permissions to use various electrification systems. You may not like my phraseology but I thought the meaning was clear enough.

Please explain how the collapse of the Glanrhyd Bridge with a DMU on it has even the slightest relevance to the safe working depth for water adjacent to powered 3rd rail?

In addition could you explain how an electric current flowing through a human body providing a path from conductor rail to earth could bring out the 10kA circuit breakers when it is difficult enough to guarantee bringing them out with a short circuiting bar?

 

[Class377/5]

This shows you have a very clear lack of understanding of railways ....

Train crew are trained for evacuation of trains in emergencies (and evacuation will only be done in an emergency, not because of a "failed train") .... there are Rules and Regulations that cover detraining of passengers and procedures to follow .... those procedures will include current isolation (ideally requesting it via signaller and ECC) and always using the short circuit bar to ensure the current cannot be switched back on .... the procedures will also include things like stopping all trains on other running lines, telling passengers how to alight safely down the ladder, how to walk on the track (step ballast to ballast, do not walk on sleepers or rails as they may be slippery), walk in the cess, etc etc etc etc etc .... the driver will always put the short circuit bar down, so the live rail is not live (but always treat it as if it IS live at all times) .... this sort of thing is drummed into train crews during their training and beyond ....

and if you're working under the wires, training includes the same things, but "beware of the overhead wires, treat them as live at all

next time you're at the station taking down numbers, take a closer look at the trains .... you'll see little yellow signs with a black lightning bolt .... they say something like "Danger: Overhead Wires" .... here's some i found for you, check the offside cab windows .... http://www.therailwaycentre.com/Pages EMU/Recognition EMU/IllusEMU_317.html

i haven't seen any yet saying "Danger: Live Rail" ....

Seriously you really need to listen not argue with everyone on here. As for not understanding the railways. What a joke. I'm railway control staff so I'm fully aware of what needs to be done. In fact I used to be trainned for train evacuation.

Drop the attitude as some on here are far more experienced on here and if you want to ask a question do so but don't just be a idiot for the sake of it.

By the way the safety case will take into account what measures when a driver isn't about to perform his duties. It's the whole picture not the idea you have of a perfect situation where driver s time to complete needed work prior to getting people off. Cases like fire he may not have time and could order people off the train without delay to save lives. This means everyone off and get a block placed.

As for sitting on a station getting number, why be outside when I've full access to all IT for every train and can watch from above?

Couple of questions for you to answer instead of insulting if you can do so....

When did anyone state it's illegal? That wording please.

Also why is DLR 3rd rail not revelant to taking about 3rd but DMU incident is?

Seems your confused in trying to get the answers that agree with what you think.

 

[EMU_Man]

My comments about the Pringle and Weir Committees are true and do explain the situation with respect to the permissions to use various electrification systems. You may not like my phraseology but I thought the meaning was clear enough.

Yes, your comments about the committees may well be true and the meaning clear, but it was pure speculation about those being reasons for new 3rd rail being prohibited. I think we've established now that there is no legislation prohibiting the laying of new 3rd rail. However, there may, as pointed out by someone else, "policy" that new electrification schemes will be 25kv AC overheard, not for safety reasons, but for performance (and other) reasons.

Please explain how the collapse of the Glanrhyd Bridge with a DMU on it has even the slightest relevance to the safe working depth for water adjacent to powered 3rd rail?

From memory, rules about running through flood water were changed. At one time, I believe the old rules allowed running through flood water that was touching the live rail but not covering it. After some incidents (which included ballast being washed away, which couldn't been seen in deep flood water), I believe the rules were changed to the effect that trains were not allowed to run where water was flowing or covered the tops of running rails. Depths were specified but I can't remember the exact depths now, it's so long ago. I think the DMU incident was one of those that triggered the rule changes - the rule changes were nationwide as the rule book was national, therefore it had an effect on the southern as well as elsewhere.

In addition could you explain how an electric current flowing through a human body providing a path from conductor rail to earth could bring out the 10kA circuit breakers when it is difficult enough to guarantee bringing them out with a short circuiting bar?

I came on here to find information - if you really want to know things like this, try google.
--- old post above --- --- new post below ---

I'm railway control staff so I'm fully aware of what needs to be done. In fact I used to be trainned for train evacuation.
.....

Cases like fire he may not have time and could order people off the train without delay to save lives. This means everyone off and get a block placed.

Are you seriously telling me that you are railway staff and that the rule book says that drivers may evacuate passengers onto running lines BEFORE blocking other running lines???
The latter is a serious safety risk .... much more of a risk than delaying evacuation for a couple of minutes ....

"Yes, Your Honour, I let 100 passengers out on the main line because of a fire. I was worried they might get burnt so I evacuated them onto the track as quickly as possible. I was going to put my TC clips down and call the signaller to block the lines once the passengers were all off the train. I was helping a pregnant woman climb down the ladder onto the track when the express ran past on the adjacent line and ploughed through my passengers."

God help us ....
--- old post above --- --- new post below ---

Please explain how the collapse of the Glanrhyd Bridge with a DMU on it has even the slightest relevance to the safe working depth for water adjacent to powered 3rd rail?

In addition to my previous reply ....

What I said was:

i THINK that (in the long distant past) we were allowed to run through flood water that was touching the live rail but not covering it (water not being a good conductor of DC) .... and i think the rules changed after a couple of incidents (the DMMU that fell in the river in wales springs to mind)

This is the report into the glanrhyd accident:
http://www.railwaysarchive.co.uk/documents/DoT_Glanrhyd1987.pdf

paragraph 88 says about running through flood water - if water is 4 inches above the top of the running rail, it will be touching the live rail on the southern - now this was 25 years ago, and i'm pretty sure that back then, the water depths quoted applied nationally (they were in the General Appendix, which was "nationwide") - if so, then my statement about running through flood water that was touching the live rail was correct

paragraph 215 is recommendations for rule changes for movements in flood water .... so i was correct that there were rule changes and also about the glanrhyd accident being one of those incidents that led to the rule changes

i didn't specify what the rule changes were and have no idea if there have been other rule changes since

 

[TGV]

The answer to the question about the existence of legislation prohibiting new 3rd rail schemes was "no" in October 2009 when NR published their RUS electrification strategy. In section 3.1 it states that overhead AC electrification is "generally the first choice" when compared to 3rd rail DC systems on a non-electrified line. If it was prevented legally, this distinction would not be made, indeed, there wouldn't be a 2nd choice.


Although that was 2009, I'm not aware of anything being introduced since then that specifically bans new DC systems. So it seems the highly likely answer to your question is that there is no such legislation, only selection based on economical, safety, environmental or performance criteria.

 

[Surreyman]

The answer to the question about the existence of legislation prohibiting new 3rd rail schemes was "no" in October 2009 when NR published their RUS electrification strategy. In section 3.1 it states that overhead AC electrification is "generally the first choice" when compared to 3rd rail DC systems on a non-electrified line. If it was prevented legally, this distinction would not be made, indeed, there wouldn't be a 2nd choice.


Although that was 2009, I'm not aware of anything being introduced since then that specifically bans new DC systems. So it seems the highly likely answer to your question is that there is no such legislation, only selection based on economical, safety, environmental or performance criteria.

Assuming that TGVs answer is unchallenged, it is surely only relevant to a handful of lines?
The only lines likely to ever be considered for 3rd rail electrification would be Ashford - Hastings/Hurst Green - Uckfield/The various un-electrified sections between Wokingham - Redhill.
A few possible extensions to the Merseyrail network a possibilty perhaps and we shouldn't forget the LT 4th rail network - diversion/extension planned for Watford already agreed.
Have I missed anything? (Volks railway doesn't count by the way).
Everything else would be 25kv OHLE.

 

[OxtedL]

Assuming that TGVs answer is unchallenged, it is surely only relevant to a handful of lines?
The only lines likely to ever be considered for 3rd rail electrification would be Ashford - Hastings/Hurst Green - Uckfield/The various un-electrified sections between Wokingham - Redhill.
A few possible extensions to the Merseyrail network a possibilty perhaps and we shouldn't forget the LT 4th rail network - diversion/extension planned for Watford already agreed.
Have I missed anything? (Volks railway doesn't count by the way).
Everything else would be 25kv OHLE.

There are a couple of question marks over what would be better in the Romsey/Salisbury directions, although if OLE appears in Southampton then the question mark starts to disappear.

 

[D365]

The 171-operated gaps in the south could well be 25kV AC OHLE if the clearance is adequate and DV 377s are available. Ditto Merseyrail extensions when the new AC-compatible fleet comes online. Rail electrification should only be retained for metro systems in the long-term.

 

[Eagle]

There are a couple of question marks over what would be better in the Romsey/Salisbury directions, although when OLE appears in Southampton then the question mark starts to disappear.

FTFY. :P

Being as Basingstoke to Southampton is being converted to OHLE (mainly for the benefit of electric freight), and via Salisbury is an important alternative freight route to Southampton, and also that now if you did third-rail you'd end up with several miles of doubly-electrified line between Basingstoke and Worting, which is a Bad Thing for reasons I've never quite understood, I think third-rail to Salisbury is now a complete nonstarter.

 

[OxtedL]

FTFY. :P

I reserve the right to remain sceptical right up until they actually start doing it.

 

[455driver]

Once you touch the live rail, you discharge the current to earth and trip the circuit breakers in the Electrical Control Centre - the current goes off.

No they wont, the human body has enough resistance to prevent enough current flowing (and it needs to be several 1000 amps worth) to trip the circuit breakers and the current will continue to flow, the internal organs will warm up, the blood (well the water actually) will start to boil and you will probably die, I am aware of one individual that stood on the con rail and running rail and boiled for a few minutes before we got the juice off who suffered no long term effects but that probably shows how low he was on the evolutionary ladder rather than the normal outcome.
--- old post above --- --- new post below ---

Slightly off-topic but do Toc staff who work on lines with electrified rails wear any insulating shoes? I only ask as I know on the Underground that staff wear shoes that would enable the wearer to stand on the juice rail and not get a shock. Admittedly the voltages on the Underground are quite a bit lower than on Network Rail.

Normal steel toe capped safety shoes and the voltage on the underground is a nominal 660v DC made up of (on the underground sections) +440v in the 3rd rail and -220v in the 4th rail), Network rail is a nominal 750v DC.
but the underground carries a much lower current than NR, remember its the volts that jolts, the current that kills.

If anywhere new is to be electrified then it will be 25kv overhead because DC 3rd rail is very inefficient and so expensive to run compared to overhead AC, 3rd rail normally has to have a feeder station every 3 miles or so where-as 25kv its a lot lot further (sorry I cant remember off hand) and DC loses a lot of energy. So while the installation of the bits on the track are cheaper for 3rd rail by the time you factor in the substations and running cost etc then 25kv (as long as its designed and built to a decent standard) is much much cheaper in the long run.

 

[Class377/5]

Are you seriously telling me that you are railway staff and that the rule book says that drivers may evacuate passengers onto running lines BEFORE blocking other running lines???
The latter is a serious safety risk .... much more of a risk than delaying evacuation for a couple of minutes ....

"Yes, Your Honour, I let 100 passengers out on the main line because of a fire. I was worried they might get burnt so I evacuated them onto the track as quickly as possible. I was going to put my TC clips down and call the signaller to block the lines once the passengers were all off the train. I was helping a pregnant woman climb down the ladder onto the track when the express ran past on the adjacent line and ploughed through my passengers."

God help us ....

Why are you trying to make this a fight. In an incident like a fire, passengers won't wait for a driver but get themselves off the train as they may be in instant danger.

There has already been cases of people getting off the train without warning so expecting the driver to know in time for every event is madness. Fact is when planning, this is taken I to account in the risk factors.

Perhaps listen and discuss rather than attack.

 

[455driver]

I will do this post, I cant be bothered to pull the rest of them apart!

This shows you have a very clear lack of understanding of railways ....

Kettle and pot!

Train crew are trained for evacuation of trains in emergencies (and evacuation will only be done in an emergency, not because of a "failed train") .... there are Rules and Regulations that cover detraining of passengers and procedures to follow Blah blah blah

We are trained in 2 types of evacuation, controlled (as you describe) and emergency (the clue is in the name) or are you saying that we are to leave 100 people inside a coach of a packed peak hour train to burn to death while we get the juice turned off?

and if you're working under the wires, training includes the same things, but "beware of the overhead wires, treat them as live at all times" ....

As do we with the 3rd rail.

next time you're at the station taking down numbers, take a closer look at the trains .... you'll see little yellow signs with a black lightning bolt .... they say something like "Danger: Overhead Wires" .... here's some i found for you, check the offside cab windows .... http://www.therailwaycentre.com/Pages EMU/Recognition EMU/IllusEMU_317.html
i haven't seen any yet saying "Danger: Live Rail" ....

Next time you are on a train in 3rd rail land look inside the vestibule on the train or at the end of a station platform.

Oh in case you are wondering yes I am a mainline driver on the former Southern Region.

 

[Surreyman]

FTFY. :P

Being as Basingstoke to Southampton is being converted to OHLE (mainly for the benefit of electric freight), and via Salisbury is an important alternative freight route to Southampton, and also that now if you did third-rail you'd end up with several miles of doubly-electrified line between Basingstoke and Worting, which is a Bad Thing for reasons I've never quite understood, I think third-rail to Salisbury is now a complete nonstarter.

Agree with third rail to Salisbury being a non-starter, begs a question about Reading/Basingstoke to Southampton, we know that this has been given the go-ahead for 25kv but I assume that it will remain effectively 25kv AND 750DC.
1. Entire Desiro fleet has to access Siemens maintenance depot in Southampton and while they can in THEORY be converted to dual voltage the cost would be enormous.
(yes they could go via Fareham but thats a real run around).
2. Trains have to continue to Bournemouth/Weymouth on 750DC.
Can anyone comment on the technical issues of track electrified on 2 different systems?

 

[Eagle]

I don't know why dual electrification is a Bad Thing, but the plans are for the third rail to be ripped out from Basingstoke to Southampton (or wherever, it'll have to be at least Millbrook to access the western docks). So SWT is going to need a lot of dual-voltage stock...

(However, sending a third-rail-only unit from London to Northam via Guildford and Fareham isn't actually that much longer than going via the mainline.)

 

[AndyLandy]

Agree with third rail to Salisbury being a non-starter, begs a question about Reading/Basingstoke to Southampton, we know that this has been given the go-ahead for 25kv but I assume that it will remain effectively 25kv AND 750DC.
1. Entire Desiro fleet has to access Siemens maintenance depot in Southampton and while they can in THEORY be converted to dual voltage the cost would be enormous.
(yes they could go via Fareham but thats a real run around).
2. Trains have to continue to Bournemouth/Weymouth on 750DC.
Can anyone comment on the technical issues of track electrified on 2 different systems?

Last I heard, you can't run both 3rd rail and AC along the same length of track since the earths are different (One's fixed, the other uses a floating earth? Something along those lines.) I was under the assumption that the entire Desiro fleet (or at least a fair proportion of them) would be fitted with pantographs to operate as dual voltage units. I'd be surprised if the cost really is all that enormous in the grand scheme of things.

 

[Eagle]

I'd be surprised if the cost really is all that enormous in the grand scheme of things.

Economies of scale; the more you do at once the cheaper it turns out.

 

[AndyLandy]

Economies of scale; the more you do at once the cheaper it turns out.

That and the fact that the 444s and 450s were designed from the ground up to be easily converted to dual voltage. It should just be a case of (simply) fitting a pantograph and a transformer.

 

[Andyjs247]

I understand it's the 'Electricity at Work regulations' in the context of preventing access to live conductors by unskilled personnel which is usually alleged to be the reason for the so called ban, so it's a part of Health and Safety associated legislation.
...

Regulation 7 of the The Electricity at Work Regulations 1989 states...

Insulation, protection and placing of conductors

7. All conductors in a system which may give rise to danger shall either–

(a)be suitably covered with insulating material and as necessary protected so as to prevent, so far as is reasonably practicable, danger; or
(b)have such precautions taken in respect of them (including, where appropriate, their being suitably placed) as will prevent, so far as is reasonably practicable, danger.

In the railway context, the DC 3rd rail and AC 25kV OHLE contact wire are live conductors but are not covered with insulating material. The key phrase here is "suitably placed". In the generic case, danger is prevented by putting the conductor out of reach, which in practice means high up and/or protected by barriers (secure fencing?).

As has been stated elsewhere, there is no specific legislation as far as I am aware to prevent 3rd rail systems.

As well as the Health and Safety at Work Act 1974 and various H&S regulations (mentioned elsewhere in the context of electrical safety) there is also the IEEE Wiring Regulations (BS7671) which relate to design. If (heaven forbid) there was to be a fatal accident then the Corporate Manslaughter and Corporate Homicide Act 2007 may also be relevant.

I was under the impression that urine as a constant flow replicates rainfall by being in droplet form and does not conduct electricity.

Well put it this way, I wouldn't want to pee on the 3rd rail given that urine will conduct electricity better than water/rainwater.

You could walk barefoot on a juice rail (have seen it done) as long as you don't earth it.

You could; for the same reason as birds can perch on power lines (even ones which carry 400kV) and don't get fried. In effect what you have is an equipotential zone or Faraday cage. No potential difference; no current = safe.

urine forms droplets like rain .... DC needs a continuous circuit in order to flow .... it can't jump like AC does .... so urination onto DC 3rd rail won't cause electric shock ....

I beg to differ. Electricity can jump/arc (whether it is DC or AC). How far depends on the potential difference, and how big the gap is. Your petrol driven car requires a spark which comes from a DC battery for example.

No they wont, the human body has enough resistance to prevent enough current flowing (and it needs to be several 1000 amps worth) to trip the circuit breakers and the current will continue to flow.

Fact is it doesn't take much current to kill - as little as 50 - 80mA (milliamps) (0.05 - 0.08A) can have fatal consequences. Death is likely to occur as a result of ventricular fibrillation and severe internal and external burns. All new domestic electrical installations (230V) incorporate some form of RCD protection. The RCD will shut off the power and is normally triggered with a fault current of 30mA.

Normal steel toe capped safety shoes and the voltage on the underground is a nominal 660v DC made up of (on the underground sections) +440v in the 3rd rail and -220v in the 4th rail), Network rail is a nominal 750v DC.
but the underground carries a much lower current than NR, remember its the volts that jolts, the current that kills.

Higher voltage (potential) means a lower current is required for the same power output [Power = Volts x Amps]. Electricity can be distributed much more efficiently using AC. The voltage can be changed much more easily too using transformers. Higher transmission voltages (up to 400kV) means the current is less and transmission losses (voltage drop) is reduced / efficiency increased.

If anywhere new is to be electrified then it will be 25kv overhead because DC 3rd rail is very inefficient and so expensive to run compared to overhead AC, 3rd rail normally has to have a feeder station every 3 miles or so where-as 25kv its a lot lot further (sorry I cant remember off hand) and DC loses a lot of energy. So while the installation of the bits on the track are cheaper for 3rd rail by the time you factor in the substations and running cost etc then 25kv (as long as its designed and built to a decent standard) is much much cheaper in the long run.

I personally doubt if we will see any further 3rd rail installations, certainly not large scale. Depending on the outcome of Basingstoke-Southampton Port conversion to OHLE we may well see other conversions in the not too distant future. Channel Tunnel-Ashford-Tonbridge-Redhill-Guildford-Reading anyone?

 

[455driver]

Fact is it doesn't take much current to kill - as little as 50 - 80mA (milliamps) (0.05 - 0.08A) can have fatal consequences. Death is likely to occur as a result of ventricular fibrillation and severe internal and external burns. All new domestic electrical installations (230V) incorporate some form of RCD protection. The RCD will shut off the power and is normally triggered with a fault current of 30mA.

What has that got to do with the circuit breakers not opening in a sub station?

Your post has absolutely nothing to do with what we are talking about.

 

[island]

Last I heard, you can't run both 3rd rail and AC along the same length of track since the earths are different (One's fixed, the other uses a floating earth? Something along those lines.)

City Thameslink.