Why no longer Third Rail Electrification?

[lancastrian]

If there is already a thread about this, I am sorry to ask the question again.

My question is basically simple, why can we not extend the 3rd Rail systems on the Southern Region and Merseyrail? Neither will be massive extensions just fill in sections.

Also it would not require massive infrastructure work in raising bridges, etc.
So why can we not do these 3rd Rail extensions.

 

[GRALISTAIR]

The pinned thread at the top of the page is your friend

http://www.railforums.co.uk/showthread.php?t=138487


I have also taken the liberty of extracting two threads on the issue - it has been discussed to death

http://www.railforums.co.uk/showthread.php?t=128993

http://www.railforums.co.uk/showthread.php?t=130877

 

[yorksrob]

All straw man arguments.

There's no good reason why we cannot extend the third rail to existing networks as has been the case for several decades.

 

[futureA]

All straw man arguments.

There's no good reason why we cannot extend the third rail to existing networks as has been the case for several decades.

Why would you bother extending an outdated standard?

 

[najaB]

All straw man arguments.

I think you don't understand what a straw man argument is...

 

[455driver]

Why would you bother extending an outdated standard?

Why would you extend a 3rd rail network using 25KV overhead?

Extensions to existing 3rd rail networks are allowed, new 3rd rail networks are not.

 

[158756]

Why would you bother extending an outdated standard?

Because the ruinously expensive current standard won't be being extended anywhere either soon.

 

[D365]

Because it's a ludicrous and archaic system for anything other than low speed metros.

Because the ruinously expensive current standard won't be being extended anywhere either soon.

What current standard?

 

[Tio Terry]

Because it's a ludicrous and archaic system for anything other than low speed metros.



What current standard?

At a guess, the Energy Technical Standard for Interoperability.

 

[najaB]

Because the ruinously expensive current standard won't be being extended anywhere either soon.

The revised OLE standard isn't ruinously expensive if you design to it from the start. The expense has come in because work was started to the old standard and needs to be redone to the new. There isn't much difference in the cost of raising a bridge by 50cm vs 75cm, but it's expensive to raise it by 50cm and then raise it again by 25cm.

 

[Verulamius]

This publication from the Office of Rail and Road is relevant: http://orr.gov.uk/__data/assets/pdf_file/0017/17621/dc-electrification-policy-statement.pdf

ORR’s most significant concern in regard to legacy third rail systems (the “legacy network”) is the running of bare, live conductors through publicly accessible areas. These conductors are not insulated or shrouded. The legacy network does not allow quick, secure isolations, and exposes individuals to a range of risks whilst carrying out isolations. Due to the difficulty in obtaining isolations on the legacy network, a lot of work tends to be carried out on or near the live conductor, further undermining safety and weakening compliance with the applicable legislation. This is not an abstract or theoretical risk: the harm done to both workers and members of the public by the legacy network occurs significantly more frequently than on the overhead AC network. A duty holder proposing the laying of new bare third rail (as used across the legacy network) would therefore have to make a compelling case that it had considered all other possibilities and could satisfactorily demonstrate that all such possibilities would be grossly disproportionate in comparison to using third rail.

 

[D365]

The revised OLE standard isn't ruinously expensive if you design to it from the start. The expense has come in because work was started to the old standard and needs to be redone to the new. There isn't much difference in the cost of raising a bridge by 50cm vs 75cm, but it's expensive to raise it by 50cm and then raise it again by 25cm.

Is this what has been happening on the Great Western?

 

[najaB]

Is this what has been happening on the Great Western?

In part. But the Great Western has its own unique issues to deal with too.

 

[3141]

This publication from the Office of Rail and Road is relevant: http://orr.gov.uk/__data/assets/pdf_file/0017/17621/dc-electrification-policy-statement.pdf

Thanks for that - very interesting. Since I live between Basingstoke and Salisbury I'd like to see my line electrified, and the simplest approach would be another 35 miles of third rail. Doing it with 25kv AC overhead would require new trains, or at the very least special modifications to existing ones, for an operation that amounts to a very small fraction of the south western network. That contrasts with the Ashford - Hastings situation, where trains with all the equipment to run on OHLE already exist. Looking at the amount of new housing that will be built at several locations along the line, and also west of Salisbury, it would be frustrating if a straightforward extension of third rail could not take place because ORR has decided to have a presumption against it, while the AC alternative looks completely unlikely.

 

[swt_passenger]

Doing it with 25kv AC overhead would require new trains, or at the very least special modifications to existing ones, for an operation that amounts to a very small fraction of the south western network.

The 450 and 444 fleets are 3 phase AC traction units that currently get their power from third rail only, but they were delivered AC fit to receive (capable), and so are the 707s.

It isn't actually a 'special modification' at all really. But they'd all be needed for their existing diagrams anyway.

But I'm getting a sense of deja vu here, how many times has the presumption against third rail extensions been discussed since 2012?

 

[rebmcr]

Thanks for that - very interesting. Since I live between Basingstoke and Salisbury I'd like to see my line electrified, and the simplest approach would be another 35 miles of third rail. Doing it with 25kv AC overhead would require new trains, or at the very least special modifications to existing ones, for an operation that amounts to a very small fraction of the south western network. That contrasts with the Ashford - Hastings situation, where trains with all the equipment to run on OHLE already exist. Looking at the amount of new housing that will be built at several locations along the line, and also west of Salisbury, it would be frustrating if a straightforward extension of third rail could not take place because ORR has decided to have a presumption against it, while the AC alternative looks completely unlikely.

Why would any electrification scheme cover only the 35 miles from your station to the closest electrified section...?

 

[ExRes]

Because it's a ludicrous and archaic system for anything other than low speed metros.

I'm never quite sure what 'low speed' is supposed to mean, is 100mph low speed?

 

[rebmcr]

I'm never quite sure what 'low speed' is supposed to mean, is 100mph low speed?

No, and hence the existing installation is ludicrous and archaic (at least for some routes).

 

[D365]

Third rail shouldn't really be used for speeds greater than 75mph, and even that's pushing it.

 

[455driver]

Third rail shouldn't really be used for speeds greater than 75mph, and even that's pushing it.

Why?
It is routinely used every day up to 100mph so I dont understand your point!

 

[ExRes]

Third rail shouldn't really be used for speeds greater than 75mph, and even that's pushing it.

I don't understand your reasoning, as an example we did DC testing on 325s between Ashford and Paddock Wood, 0-100-0-100-0 without a single problem, 73 hauled TPOs at line speed, no problem, the much venerated Wessex Electrics did their thing for years and so on, why a 75mph limit?

 

[D365]

I don't understand your reasoning, as an example we did DC testing on 325s between Ashford and Paddock Wood, 0-100-0-100-0 without a single problem, 73 hauled TPOs at line speed, no problem, the much venerated Wessex Electrics did their thing for years and so on, why a 75mph limit?

In terms of efficiency, DC electrification is much more wasteful. The main benefit to using it on metro systems is that each train does not have to carry a transformer/pantograph/inverter.

 

[AM9]

I don't understand your reasoning, as an example we did DC testing on 325s between Ashford and Paddock Wood, 0-100-0-100-0 without a single problem, 73 hauled TPOs at line speed, no problem, the much venerated Wessex Electrics did their thing for years and so on, why a 75mph limit?

Those lines where higher speeds are regularly run using 3rd rail require higher maintenance levels and much higher current capability than elsewhere. The SWML and BML have very intense maintenance regimes and still there are problems occasionally. Add that to the requirement to cripple most modern EMUs/Locos to prevent them overloading the supply, which then brings operational limitations that wouldn't exist on all but the most basic OLE routes.

 

[Deepgreen]

Because it's a ludicrous and archaic system for anything other than low speed metros.

Possibly, but it copes OK with 90-100mph running - about right for the ex-Southern Region network. Given the number of OHLE failures of late, I find myself questioning both systems. I understand the safety aspect that stands against third rail, but it tends to be less susceptible to the major weather problem in the UK, i.e. wind (rather than snow/ice, which are the downfall of third rail). The electrical efficiency aspects are vital too, of course.

Essentially, we have two type of electrification in the UK, and 25kv OHLE will probably be the 'winner' in the long term, but to convert the third rail network will be horribly expensive. There has been huge debate about the definition and likelihood of third rail extension, with some saying there will never be another route foot of it laid, while others foresee substantial in-fills (North Downs line, etc.). There has also been a great deal of discussion about the over-engineering of the latest schemes (e.g. GWR) compared with much less visually-intrusive equipment for much faster line speeds elsewhere (e.g. French high-speed routes).

 

[D365]

If we're converting a 100mph section of third rail to 100mph OHLE, such as from Basingstoke southwards, I imagine that it won't need to be engineered to the same standard as the Great Western electrification.

 

[rebmcr]

Possibly, but it copes OK with 90-100mph running - about right for the ex-Southern Region network. Given the number of OHLE failures of late, I find myself questioning both systems. I understand the safety aspect that stands against third rail, but it tends to be less susceptible to the major weather problem in the UK, i.e. wind (rather than snow/ice, which are the downfall of third rail). The electrical efficiency aspects are vital too, of course.

Essentially, we have two type of electrification in the UK, and 25kv OHLE will probably be the 'winner' in the long term, but to convert the third rail network will be horribly expensive. There has been huge debate about the definition and likelihood of third rail extension, with some saying there will never be another route foot of it laid, while others foresee substantial in-fills (North Downs line, etc.). There has also been a great deal of discussion about the over-engineering of the latest schemes (e.g. GWR) compared with much less visually-intrusive equipment for much faster line speeds elsewhere (e.g. French high-speed routes).

The same 'over-engineering' that you decry in your second paragraph is the answer to the weather-based unreliability in your first!

 

[Deepgreen]

The same 'over-engineering' that you decry in your second paragraph is the answer to the weather-based unreliability in your first!

I didn't necessarily decry it, I was comparing the GWR example of OHLE with, for example, the French high-speed infrastructure - does that suffer a large amount of weather (wind) disruption owing to its 'minimalist' nature (I don't know - a genuine question)?

 

[Chester1]

Merseyrails new trains have been designed to make it straightforward to convert them to dual volt. If the Merseyrail network is extended it will be much cheaper to do it with overhead wires than third rail. The loop and link tunnels do not have the height to install overhead wires but I expect the rest of the network will switch to overhead electrification when the current systems become life expired. What is the benefit of extending the third rail network or replacing life expired third rail rather than using dual volt stock?

 

[D365]

What is the benefit of extending the third rail network or replacing life expired third rail rather than using dual volt stock?

Bridge clearances are the only real cost saving.

 

[Camden]

In terms of efficiency, DC electrification is much more wasteful. The main benefit to using it on metro systems is that each train does not have to carry a transformer/pantograph/inverter.

I don't believe this is either true or clear cut. For higher speed lines with infrequent stops (south) AC is more efficient, however for lower speed lines with frequent stops (Merseyrail) DC is more efficient.