Chris125
Established Member
You get what you pay for, which in the case of the ECML is delays everytime it gets a bit breezy. It seems experience of BR's on-the-cheap wiring has shown that the long term costs outweigh any short term benefit.
Chris
-
Our new ticketing site is now live! Using either this or the original site (both powered by TrainSplit) helps support the running of the forum with every ticket purchase! Find out more and ask any questions/give us feedback in this thread!
Cost of electrification
- Thread starter TheWalrus
- Start date
- Status
You get what you pay for, which in the case of the ECML is delays everytime it gets a bit breezy. It seems experience of BR's on-the-cheap wiring has shown that the long term costs outweigh any short term benefit.
Chris
Sponsor Post - registered members do not see these adverts; click here to register, or click here to log in
R
RailUK Forums
Well yeah they come down a bit, although north of Bishop Stortford seems generally okay. I should hope therefore that the GWML overheard structures are made out of titanium for what its costing us
Old Timer
Established Member
Forget the GW its all a fantasy. Scorched economic earth policy.
There is a much better payback elsewhere and frankly there is little benefit in electrifying to Bristol, let alone into the wilderness beyond it.
There is a much better payback elsewhere and frankly there is little benefit in electrifying to Bristol, let alone into the wilderness beyond it.
Bishop Stortford isn't on the ECML. At least, it wasn't last time I checked
Very much on the West Anglia line.Bishop Stortford isn't on the ECML. At least, it wasn't last time I checked
I know, but it was electrified around the same time I believe and doesn't seem to be suffering massively despite not being electrified at a cost of a trillion pounds a inch.
Tbh I think its probably a good idea to electrify it and shove the pendolino's on there as it would reduce journey times significantly and save on costs in the long run.
Yes, your point being. . .
No need to put it so rudely! The point is that the tensioning and set up required for 125mph running and the wire/panto interaction are rather different compared to 90mph.
And I doubt that Pendolinos on the GW would save significant time for the most part compared to a non-tilt high speed electric train with the same installed power, considering how straight most of the line to Bristol is. Tilt can only save time by allowing a train to run 15% or so faster round curves.
And I doubt that Pendolinos on the GW would save significant time for the most part compared to a non-tilt high speed electric train with the same installed power, considering how straight most of the line to Bristol is. Tilt can only save time by allowing a train to run 15% or so faster round curves.
The wires on the ECML tend not to come down in isolation. They come down when winds combine with the vibrations that high speed services cause in the wires result in the pantographs tangling the wires. Slower speeds cause less vibrations, thus less problems
No offence intended man, well it still has significant enough curves to be worth them being used there, even if they wouldn't be as effective as on the WCML. Also with electrification possibly extending down toward Cornwall and Devon the Pendolinos could generate significant time savings on lines there.
I didn't think that was the problem? Its not a matter of more vibrations as such its a matter of the frequency of the vibrations creating reasonance which could bring wires down in the manner that you describe. This is also the reason why most electric trains go with one pantograph up, to avoid creating a standing wave. The problem seems to be that the supports holding the wires up are spaced too far apart so that there is more pressure upon each one, and hence under higher wind speeds they sometimes come down. However I don't think that would necassarily be to do with the speed of the trains on the line, as I should imagine the fundamental frequency the materials used is higher than that which could be created by the train.
No they don't... units in multiple need all their pantos up, class 91+mark4 sets only have one panto, Pendos only use one to avoid too much wear more than anything else, and 200mph+ Shinkansen operating in multiple can have four pantographs up.
It depends upon the tension used. The Eurostar goes with multiple pantographs up because its so long that the oscillations are damped sufficiently in between, but normal TGV's only opperate with the rear pantograph up to avoid creating a standing wave, unless they are running in multiple in which case two can be raised. On slower lines it doesn't create a problem because the train doesn't create a standing wave similar to the speed at which it is traveling, but as I said before its not about 'more' vibrations its about the frequency of those vibrations and in any case I don't think its that which is bringing down the lines on the ECML.
Ploughman
Established Member
I don't think its that which is bringing down the lines on the ECML.
From comments made by OHLE design staff in the mid 90s. the problem is down to money.
Increased mast spacing and standard of fixing used to secure the contact wire to the system being the main items.
The spacing created added stresses and increased the likelihood of the wires coming down.
From comments made by OHLE design staff in the mid 90s. the problem is down to money.
Increased mast spacing and standard of fixing used to secure the contact wire to the system being the main items.
The spacing created added stresses and increased the likelihood of the wires coming down.
ChrisCooper
Established Member
Another problem on the ECML can be that strong crosswinds will cause the midspan of the contact wire to offset to the point where it slips off the side of the pantograph. The pantograph then raises and before there is time even for the automatic dropping device to work the contact wire is pulled back towards the centreline by the next mast, passing under the pan head which then chops through the droppers and causes a nice mess. The main area where that occurs is on the part where it really does run along the East Coast. The spacing of the masts and the tension of the contact wire are both factors involved in this.
Yeah, thats what the problem seems to be, they should probably reduce the spacing along that problem section which you mentioned. It does seem to be a problem confined to the ECML though, and I guess this is down to it opperating in areas with higher wind speeds.
Its the mast spacing and design, not higher wind speeds that are the problem with the OHLE. How many more times does it have to be said?
IIRC, speed restrictions of 80mph(?) come in at a much lower wind speed on the ECML compared to, for instance, the WCML, which again IIRC, at 90/95mph? *
*I think this info was stated thus in the RAIB report in to the blown off empty containers incidents. But its a while ago since I read it.
I can't understand what your saying here? The Government doesn't dictate how fast the wind travels, thats an impossible suggestion. I've said its about too greater mast spacing, that is indeed the problem, but its made a particular problem on the ECML as opposed to say Bishop Stortford - Cambridge because, particularly in the north it travels through some areas such as along the coast near Berwick which consistantly have higher wind speeds which which either (and prehaps someone could clarify which) bring down the wires by sheer force or by causing vibrations at fundamental frequency.
asylumxl
Established Member
Or London Overground for that matter!
Or First Capital Connect TL. You are usually greeted with a full train from just Bedford lol.
Old Timer
Established Member
There is no one specific underlying reason for the problem with the OHL north of Peterborough, it is simply a combination of factors which over the years have come together.
Criticism of the original OHL Engineers is unfair as without their efforts we may well not have had a fully electrified route to Edinburgh.
Firstly it must be remembered that the extension of the OHL beyond Peterborough was carried out using "spare" equipment from previous electrification projects. It was NOT a haphazard collection, as craftily the man in charge of OHL construction at the BRB had knowingly over-ordered a lot of equipment, and so had a strategic stockpile for which the other Projects had paid.
The issue was that in those times, a properly costed scheme would never have gotten off the ground, so cleverly the spare capacity of the OHL design office was used to carry out surveys and prepare a lot of the behind the scenes work. The effect of this was to produce a scheme where the upfront costs were considerably lower and stood a better chance of approval. In addition OHL Construction equipment and resources that were standing "spare" were used initially to start the works off.
The Equipment design was Mk3b, which in those days was a design that had been developed for a maximum of 100mph linespeed. The downside of this was that the Structure spacing was determined by that, as was the tensioning of the equipment. In those days there was no specific design for 125 mph running.
In order to achieve 125 mph running, the tension of the OHL was increased, however the Equipment was still designed to operate at a lower tension and this meant that the various fittings were going to have a shorter lifespan as a consequence.
The train service at that time was less than it is now, being if I recall correctly being three Class 1s an hour (Leeds/Newcastle/Edinburgh). The power demands were of course much less at that time, so the design worked.
The scheme was always going to require an upgrade if the services were going to materially increase in frequency, consequently increasing power demands.
Of course this is what has happened over the years but in fairness to Network Rail, both the GN Inner Suburban and the Midland Suburban schemes have reached their end of life, and in the case of the GN, there have been unexpected dilapidations to the headspan and cross span wires which have resulted in the need for all these to be replaced. In the case of the Midland, some stretching of these wires has been experienced but the bigger issue there is that the power demands are considerably greater than designed for.
In addition both routes have now experienced considerable wear in the Contact wire and wear in the bridles of the Catenary wire (a bridle is the arrangement where the Catenary wire passes over the Upper Cross span wire).
This together with the well known problems of the GE have swallowed up considerable financial resources which means that the GN main line has been de-prioritised.
Unfortunately the OHL systems tend to be installed and forgotten about.
Other issues that have caused the GN main line to be more prone to problems, is the subjective belief that the weather has worsened, with more instances of strong winds and temperature variations which in turn put strains onto the Equipment.
People have commented on what is technically known as "blow-off", the situation where the OHL contact wire is blown off the pantograph head.
This is normally a situation which is more likely on curves, although it can occur on the straight too. As should be known already, the contact wire is "staggered" across the four foot from the centre line of the track so as to equalise the wear on the pantograph head.
The precise measurement includes a calculation of the potential movement under wind loading towards one side of the track, although bearing in mind the fact that the mid-point of the wire should always be zero as it is at maximum stagger at the registration fitting.
Because however the track is never perfectly straight, 0mm stagger can, and does, ofter occur to one end of the wire span. This practically gives different values at each registration point and in the very worst cases (normally curves) can result with the wire being at maximum deviation from the centreline of the pantograph.
Because this effect is well known and the stagger adjusted to manage the issue, a problem will normally only occur when there are sudden wind gusts above those which the design has been developed to withstand. It is certainly the case that higher windspeeds are being experienced in comparison with those when the system was designed, although "blow-off" dewirements are quite rare.
A bigger issue is the mechanical failure of the system which is caused by high power demands, especially when the pantograph is losing contact with the contact wire. The efffect is the generation of an arc which in turn leads to mechanical and metallurgical damage to the stainless steel droppers. These then fail in due course allowing the contact wire to hang loose, and in some cases allowing it to be hooked up by the pantograph horns.
There are other more complex issues but this is a very very simplified thumbnail sketch of the principal issues, and will hopefully give an understanding of the reasons.
Remediation will not be easy because as a consequence of Network Rail's attitude towards its Contractors, considerable numbers of highly experienced OHL Construction staff have now emigrated to other Countries where their skills are better recognised and more respected.
Unfortunately Network Rail believe that OHL maintenance staff can construct the equipment. The fact is that they cannot. They may be good at restoring equipment to a workable state, but Construction requires very different skills which these people do not have, and this can be seen by some of the "cock-ups" that have occurred when they have been used for that.
Future demands for skilled OHL engineers and linesmen in the UK far outstrips existing supply and no-one who has moved away from working on Network Rail jobs wants to come back. As a consequence of their actions Network Rail have contributed to the biggest contraction of skilled people in the Industry ever, and have set the scene for future reductions in electrification schemes through the lack of skilled resources.
Criticism of the original OHL Engineers is unfair as without their efforts we may well not have had a fully electrified route to Edinburgh.
Firstly it must be remembered that the extension of the OHL beyond Peterborough was carried out using "spare" equipment from previous electrification projects. It was NOT a haphazard collection, as craftily the man in charge of OHL construction at the BRB had knowingly over-ordered a lot of equipment, and so had a strategic stockpile for which the other Projects had paid.
The issue was that in those times, a properly costed scheme would never have gotten off the ground, so cleverly the spare capacity of the OHL design office was used to carry out surveys and prepare a lot of the behind the scenes work. The effect of this was to produce a scheme where the upfront costs were considerably lower and stood a better chance of approval. In addition OHL Construction equipment and resources that were standing "spare" were used initially to start the works off.
The Equipment design was Mk3b, which in those days was a design that had been developed for a maximum of 100mph linespeed. The downside of this was that the Structure spacing was determined by that, as was the tensioning of the equipment. In those days there was no specific design for 125 mph running.
In order to achieve 125 mph running, the tension of the OHL was increased, however the Equipment was still designed to operate at a lower tension and this meant that the various fittings were going to have a shorter lifespan as a consequence.
The train service at that time was less than it is now, being if I recall correctly being three Class 1s an hour (Leeds/Newcastle/Edinburgh). The power demands were of course much less at that time, so the design worked.
The scheme was always going to require an upgrade if the services were going to materially increase in frequency, consequently increasing power demands.
Of course this is what has happened over the years but in fairness to Network Rail, both the GN Inner Suburban and the Midland Suburban schemes have reached their end of life, and in the case of the GN, there have been unexpected dilapidations to the headspan and cross span wires which have resulted in the need for all these to be replaced. In the case of the Midland, some stretching of these wires has been experienced but the bigger issue there is that the power demands are considerably greater than designed for.
In addition both routes have now experienced considerable wear in the Contact wire and wear in the bridles of the Catenary wire (a bridle is the arrangement where the Catenary wire passes over the Upper Cross span wire).
This together with the well known problems of the GE have swallowed up considerable financial resources which means that the GN main line has been de-prioritised.
Unfortunately the OHL systems tend to be installed and forgotten about.
Other issues that have caused the GN main line to be more prone to problems, is the subjective belief that the weather has worsened, with more instances of strong winds and temperature variations which in turn put strains onto the Equipment.
People have commented on what is technically known as "blow-off", the situation where the OHL contact wire is blown off the pantograph head.
This is normally a situation which is more likely on curves, although it can occur on the straight too. As should be known already, the contact wire is "staggered" across the four foot from the centre line of the track so as to equalise the wear on the pantograph head.
The precise measurement includes a calculation of the potential movement under wind loading towards one side of the track, although bearing in mind the fact that the mid-point of the wire should always be zero as it is at maximum stagger at the registration fitting.
Because however the track is never perfectly straight, 0mm stagger can, and does, ofter occur to one end of the wire span. This practically gives different values at each registration point and in the very worst cases (normally curves) can result with the wire being at maximum deviation from the centreline of the pantograph.
Because this effect is well known and the stagger adjusted to manage the issue, a problem will normally only occur when there are sudden wind gusts above those which the design has been developed to withstand. It is certainly the case that higher windspeeds are being experienced in comparison with those when the system was designed, although "blow-off" dewirements are quite rare.
A bigger issue is the mechanical failure of the system which is caused by high power demands, especially when the pantograph is losing contact with the contact wire. The efffect is the generation of an arc which in turn leads to mechanical and metallurgical damage to the stainless steel droppers. These then fail in due course allowing the contact wire to hang loose, and in some cases allowing it to be hooked up by the pantograph horns.
There are other more complex issues but this is a very very simplified thumbnail sketch of the principal issues, and will hopefully give an understanding of the reasons.
Remediation will not be easy because as a consequence of Network Rail's attitude towards its Contractors, considerable numbers of highly experienced OHL Construction staff have now emigrated to other Countries where their skills are better recognised and more respected.
Unfortunately Network Rail believe that OHL maintenance staff can construct the equipment. The fact is that they cannot. They may be good at restoring equipment to a workable state, but Construction requires very different skills which these people do not have, and this can be seen by some of the "cock-ups" that have occurred when they have been used for that.
Future demands for skilled OHL engineers and linesmen in the UK far outstrips existing supply and no-one who has moved away from working on Network Rail jobs wants to come back. As a consequence of their actions Network Rail have contributed to the biggest contraction of skilled people in the Industry ever, and have set the scene for future reductions in electrification schemes through the lack of skilled resources.
Last edited:
Old Timer
Established Member
The pantograph is held against the contact wire by an upwards force of about the same as a 2lb bag of sugar. A properly balanced pan can therefore be literally controlled by one's little finger
The OHL catenary system is a little more rigid, but cupped in the palm of the hand it is possible to move the wire upwards.
On a good piece of track, with the pan in good order and the aerofoils working, the pantograph will be held firmly against the wire, and the catenary system will lift and fall as the train passes through. This is known as "system uplift", and is partly due to the airflow of the train and partly due to the upwards pressure of the pantograph.
The faster you go the more uplift, the slower, the less.
Where the track is not in good vertical and lateral condition, eg, poor track geometry, then the pantograph will reflect that.
Where the cross-level between the rails (the "top") is poor any inbalance across the rails is magnified by a factor of 3.5, therefore for every 1mm difference, the pantograph will move sideways by 3.5mm. Added to this sway of the vehicle, there will also be a vertical response, in that as the vehicle sways to one side, it will cause the pantograph to raise slightly.
Add to this the fact the almost without doubt the along track geometry will invariably be poor and you can add a factor on for vehicle "bounce".
In turn this will cause the pantograph to develop a sinusoidal waveform into the catenary system.
This will lead to pantograph bounce, where at some point the pantograph will be out of contact with the contact wire. This can be seen most at junctions where the track condition is not good.
As the pantograph bounces under load, it causes a break and make arc. This causes a current surge which is generally drawn down through the stainless steel droppers thus leading to a deterioration of the dropper and its fittings. Arcing over a long period of time will cause the contact wire to become pitted and eventaully either it or the dropper will fail.
So in answer to your question, yes vertical "resonance" in the wire will lead to wear and damage over time.
Another very simplified answer as it is not all as cut and dried as I suggest but you will understand the basic principles.
The OHL catenary system is a little more rigid, but cupped in the palm of the hand it is possible to move the wire upwards.
On a good piece of track, with the pan in good order and the aerofoils working, the pantograph will be held firmly against the wire, and the catenary system will lift and fall as the train passes through. This is known as "system uplift", and is partly due to the airflow of the train and partly due to the upwards pressure of the pantograph.
The faster you go the more uplift, the slower, the less.
Where the track is not in good vertical and lateral condition, eg, poor track geometry, then the pantograph will reflect that.
Where the cross-level between the rails (the "top") is poor any inbalance across the rails is magnified by a factor of 3.5, therefore for every 1mm difference, the pantograph will move sideways by 3.5mm. Added to this sway of the vehicle, there will also be a vertical response, in that as the vehicle sways to one side, it will cause the pantograph to raise slightly.
Add to this the fact the almost without doubt the along track geometry will invariably be poor and you can add a factor on for vehicle "bounce".
In turn this will cause the pantograph to develop a sinusoidal waveform into the catenary system.
This will lead to pantograph bounce, where at some point the pantograph will be out of contact with the contact wire. This can be seen most at junctions where the track condition is not good.
As the pantograph bounces under load, it causes a break and make arc. This causes a current surge which is generally drawn down through the stainless steel droppers thus leading to a deterioration of the dropper and its fittings. Arcing over a long period of time will cause the contact wire to become pitted and eventaully either it or the dropper will fail.
So in answer to your question, yes vertical "resonance" in the wire will lead to wear and damage over time.
Another very simplified answer as it is not all as cut and dried as I suggest but you will understand the basic principles.
Old Timer
Established Member
The solution is a mixture of closer Structure spacing, UK1 OHL Equipment (which is designed for high speed running and will include thicker Contact wire), and possibly a power upgrade.
The problem that presents itself however is that since the OHL was installed, the method of calculating tye loading of structures has changed out of all recognition with factors of safety being further factored. The bottom line is that although those Structures will not move in a thousand years, the designers calculations will "prove" that they will fall over in the next high breeze. They then may well not be capable of being used to support the new equipment, and in any case are probably going to be inadequately spaced against the new spacing requirements, so will need to be replaced.
Mostly though they will need to be replaced because the fear of litigation has now so paralysed the design fraternity that they load factor of safety upon factor of safety until the Structure becomes so enormous as to be obvious silly, yet no-one dare challenge even the most blindingly obvious of over-engineering because their Insurers may consider that this invalidates the professional indemnity Insurance.
It truly is a mad "Alice in Wonderland World" to take anything through adesign process in the UK. Elsewhere in Europe and abroad, common sense still prevails, and there is not this fear of litigation.
It is this which results in signal bases being capable of supporting a block of flats, and OHL Structure piles so deep that occasionally they run the risk of causing a rupture the inner core of the earth. But only in the UK. :roll: :roll: :roll:
I wonder if the recent volcanic activity was not brought about by the installation of a signal post somewhere.
The problem that presents itself however is that since the OHL was installed, the method of calculating tye loading of structures has changed out of all recognition with factors of safety being further factored. The bottom line is that although those Structures will not move in a thousand years, the designers calculations will "prove" that they will fall over in the next high breeze. They then may well not be capable of being used to support the new equipment, and in any case are probably going to be inadequately spaced against the new spacing requirements, so will need to be replaced.
Mostly though they will need to be replaced because the fear of litigation has now so paralysed the design fraternity that they load factor of safety upon factor of safety until the Structure becomes so enormous as to be obvious silly, yet no-one dare challenge even the most blindingly obvious of over-engineering because their Insurers may consider that this invalidates the professional indemnity Insurance.
It truly is a mad "Alice in Wonderland World" to take anything through adesign process in the UK. Elsewhere in Europe and abroad, common sense still prevails, and there is not this fear of litigation.
It is this which results in signal bases being capable of supporting a block of flats, and OHL Structure piles so deep that occasionally they run the risk of causing a rupture the inner core of the earth. But only in the UK. :roll: :roll: :roll:
I wonder if the recent volcanic activity was not brought about by the installation of a signal post somewhere.
Agree with you about concrete-plating of structures. When Manchester Metrolink was routed through Victoria station there were some ridiculously over-engineered concrete protective barriers installed, in case a runaway tram should destroy everything in its path. Nothing done to protect against (significantly heavier) runaway trains though.
Peter Mugridge
Veteran Member
Now that reminds me of the hugely embarrasing accident BR had with the Thames Water London Ring Main when they were building the Stewart's Lane flyover for the Eurostar link to Waterloo...
Old Timer, you make me smile! I just want to thank you for your excellent technical summary of OLE which I found really interesting and helpful. I'd never understood why the ECML electification seemed so much cheaper to implement.
Jon
Pendys could probably save some considerable time on the Berks and Hants, probably running at 125 for much of the route. The line needs resignalling anyway (headways are a bit of a problem) and might get wires as far as Newbury unless that gets cut. If you include the whole route to Penzance, there's a chance of cutting an hour off the time.
Curiously, if Brunel had had electric traction available instead of the atmospheric railway, the South Devon may have been given a third rail when new.
Stations!
Have a look at Waterloo or Victoria at the available platform when the train is berthed, not all platforms at termini can take 12 coach trains.
cyclebytrain
Member
- Joined
- 11 Jul 2009
- Messages
- 311
Old timer, what is the load case here? I see wire weight, structure weight and bending with shear up to the force required to fail the wire in tension as the starting point for the load case. I've just looked at one as this Pendo coasts painfully slowly through Rugby and it looks like an extruded I section so it's not exactly going to break the bank to make it stupidly thick anyway.
I am surprised that indemnity insurance plays such a part in decisions in the railways industry -I have a quote framed "There's no indemnity insurance that will do your jail time for you. If it's wrong, don't sign it." Do you have one that's actually worth having?
Teaboy1
Member
As usual the British are handicapped by their own invention, ie H&SE and rendered thus ineffective. My industry (power, oil&gas) is about as bad as it gets today!
The French as usual show how its done;
http://www.faiveley.com/uk/categorie.php?ID=23
hit the 3 downloads and there you see how it should be done. As regard mast spacing, obviously more is better, but the old adage is that one gets what one pays for applies!!
Naturally to use full track width support (sides and top) is more costly initially but cheaper in the long run, just like the Japan rail folk use.
Short term -v- long term benefits etc, sure we have heard it a thousand times before.
When railway engineers are super-ceded by accountants and lawyers, then its time to get out.
We really are our own worst foe!!
The French as usual show how its done;
http://www.faiveley.com/uk/categorie.php?ID=23
hit the 3 downloads and there you see how it should be done. As regard mast spacing, obviously more is better, but the old adage is that one gets what one pays for applies!!
Naturally to use full track width support (sides and top) is more costly initially but cheaper in the long run, just like the Japan rail folk use.
Short term -v- long term benefits etc, sure we have heard it a thousand times before.
When railway engineers are super-ceded by accountants and lawyers, then its time to get out.
We really are our own worst foe!!
- Status