Should lines electrified with 3rd rail convert to 25Kv ac

[D365]

So you are saying that in the event of major work at Euston (remember the rider in the post that you responded to) a mix of 3rd rail and OHLE should be retained.

How many third rail platforms will be retained at Euston? Are there any regular diagrams at the moment where London Overground units switch to OHLE on the platform approach?

 

[GRALISTAIR]

Only after a number of beneficial electrification schemes are completed to lines with no electrification at all.

Exactly - unless it was part of strategic freight e.g. Southampton port to Basingstoke. Non electrified lines MUST imho be given priority.

 

[VT 390]

I definitely think that routes which have no electrification at all such as TransPennine routes should get priority over converting lines which already have electrification so that as many diesel services can be removed from the network as possible.

 

[mr_jrt]

The only reasonable case for conversion is as part of renewals, and that's because it can cost as much to renew the DC infrastructure as to replace it with new AC kit, with the advantage that you could install much of the AC kit alongside the DC, so ignoring it in favour of unelectrified lines doesn't really make sense, as the already-electrified lines are llikely to be those most intensely used already, so being able to increase their capacity by enabling more frequent, and longer, and faster trains than the DC can supply (due to greater current being available) is going to give greater benefits than switching over a more lightly-used diesel line elsewhere to AC.

Primary obstacles that increase costs are a) signalling - i.e. is it suitable for use with AC, and are the signals themselves in suitable locations once the masts go up? b) ...and tunnels (including the very short tunnels we call bridges ). The signalling issue can be dealt with as part of renewals of that separately (are all new signalling installations suitable for use with AC now?), and tunnels are usually dealt with as part of gauge enhancement improvements for freight. Where there isn't any notable containerised freight then it becomes more problematic.

As an additional consideration, when it comes to working out how to switch over viable routes you recover DC assets from lines suitable for conversion that aren't life expired and use them to renew those in problematic areas that aren't. Eventually the DC network contracts back to the inevitable core of the central London area and you just need one almighty push to finish it off, everything being dual-voltage these days really helps here. Just gotta get those extremities of the network switching over...

 

[Mark B]

Does the increased battery potential/usage on new trains make AC/DC changeover easier by allowing a "gap" between, rather than having to have a problematic/expensive dual voltage section like Thameslink? This might make "piecemeal" conversion more viable.

 

[swt_passenger]

Does the increased battery potential/usage on new trains make AC/DC changeover easier by allowing a "gap" between, rather than having to have a problematic/expensive dual voltage section like Thameslink? This might make "piecemeal" conversion more viable.

Thameslink is a special case, covering two successive stations. The complexity there isn’t a requirement for every potential future changeover location.

 

[klass43]

All mainline EMUs ordered since the noughties have been either dual system ready or convertible. Look at the DC-only class 375, 376, 377, they have pantograph wells and suspension set up for a transformer. Most ac-only EMUs have passive provision for 3rd rail collection, - fitting of shoes is a minor depot operation. A 750V DC bus is now the norm for system design.

That's how I understand the situation and it's a good idea for future-proofing.

I agree that non-electrified lines should take priority over third rail, but in the long term, DC third rail should be converted to AC OLE for safety reasons and better performance.

 

[Meerkat]

I agree that non-electrified lines should take priority over third rail, but in the long term, DC third rail should be converted to AC OLE for safety reasons and better performance.

Yes for outer suburban but would the gains be worth the huge disruption further in (lots of low bridges there!)?

 

[AM9]

Yes for outer suburban but would the gains be worth the huge disruption further in (lots of low bridges there!)?

well 'the long term' would include infrastructure repalcement for other reasons, e.g. road overbridges too narrow/not strong enough/or just beyond their working life. The difference in cost between a bridge with OLE clearance compliant with current standards and just replacing the existing limited clearance structure with the same would in many cases be negligible. Replacing worn out bridges is pretty disruptive anyway.

 

[Meerkat]

well 'the long term' would include infrastructure repalcement for other reasons, e.g. road overbridges too narrow/not strong enough/or just beyond their working life. The difference in cost between a bridge with OLE clearance compliant with current standards and just replacing the existing limited clearance structure with the same would in many cases be negligible. Replacing worn out bridges is pretty disruptive anyway.

what fraction of bridges need replacing? I suggest a rather small percentage. And fixing inner urban ones are very tricky, with limited clearance, lots of utilities, too many stations and under bridges for track lowering, and infrastructure meaning it’s hard to raise the road.

 

[AM9]

what fraction of bridges need replacing? I suggest a rather small percentage. And fixing inner urban ones are very tricky, with limited clearance, lots of utilities, too many stations and under bridges for track lowering, and infrastructure meaning it’s hard to raise the road.

It depends on how one interprets 'the long term' as I indicated above. Much of the 3rd rail non-track infrastructure is over 100 years old and approaching 180 years now. The railway has been building new and replacement bridges to dimensions that could accommodate OLE for some years now.

 

[The Ham]

Whilst I agree that we should be focusing on building new OHLE rather than replacing 3rd rail, we should also look to (over time) replacing 3rd rail where it means that it would be better to do so.

For instance it could be better to replace that through Basingstoke station when the line towards Salisbury is electrified so as to avoid a long interface between the two systems. That might mean re-electrifying Winchester to Farnborough (the latter could also help with the OHLE of the Reading/Guildford line) so that the change over is on plane track and so that feeder stations can provide backup to the other section of track.

Likewise replacing the electrification of Bournemouth to Weymouth could allow more services to run on that line

As well as being able to look at 110mph running to improve journey times (as the current services to Portsmouth now take longer than they did 30+ years ago).

 

[VT 390]

If any 3rd rail were to be replaced by overhead electrification then the Northern part of the South Western seams like the best option, not just because of improved journey times and more trains but if the Heathrow southern link goes ahead it would be easier to have through services to Paddington.

 

[klass43]

All mainline EMUs ordered since the noughties have been either dual system ready or convertible. Look at the DC-only class 375, 376, 377, they have pantograph wells and suspension set up for a transformer. Most ac-only EMUs have passive provision for 3rd rail collection, - fitting of shoes is a minor depot operation. A 750V DC bus is now the norm for system design.

Also, I may be wrong, 313s/315s (?) running on the North London Line (now London Overground) used 3rd rail, could also be fitted with pantographs.

 

[Saperstein]

Also, I may be wrong, 313s/315s (?) running on the North London Line (now London Overground) used 3rd rail, could also be fitted with pantographs.

313s are dual voltage yes, although I believe the ones Southern are using were converted to DC only?

They used to switch over from AC to DC and vice versa at a few locations on the North London Line and I’m sure other lines.

315s are AC only.

There’s a list here https://en.m.wikipedia.org/wiki/List_of_British_Rail_electric_multiple_unit_classes

 

[PTR 444]

The only third rail lines that I would seriously consider converting to OHLE are the SWML between Farnborough and Bournemouth, and the West Coastway between St Denys and Portsmouth Harbour. I say these because these are the only ones which have regular scheduled diesel services that also run under wires for another part of their journey. Converting these routes to OHLE would avoid the need for dual voltage bi-mode (or tri-mode) trains during the interim period before the entirety of the Wessex Main Line and Cross Country routes are electrified.

Basingstoke to Farnborough does not have diesel trains but I think this would be good to convert as it would permit 125mph running on this section which is largely straight. Ideally I would extend the electrification all the way to Waterloo but that would require all the existing DC units to be replaced with dual voltage, so best keep the suburban lines as third rail and make do with dual voltage for services to Basingstoke, Salisbury, Poole and Weymouth.

I know I mentioned in another thread about building a new OHLE electrified line between BSK and SOU allowing the existing SWML to remain third rail, but now I actually think it might be better to just upgrade the existing SWML between the Hampshire towns/cities since there is plenty of room for four-tracking.

 

[mr_jrt]

What DC-only stock is still in use nowadays? All the Electrostar-deriviatives are dual voltage, as are the Siemens units, which is pretty much everything on the Southern region these days, so switching over isn't a big issue. Aside from the electric spine's conversion of Basingstoke to Southampton, IIRC the rough plan proposed was to convert the extremities beyond the HS1 services extended around the coast, so everything beyond Ashford to Dover and Margate, and same beyond Ebbsfleet to Margate. You then had a logical extension of Ashford to Ore, and maybe on to Hastings with a bit of conversion.

If I were to draw up an ordered list to minimise dual-electrified sections it'd probably look a little like this in the west:

• Weymouth and Lymington to Southampton (changeover at Southampton)
  
• Southampton to Basingstoke (changeover at Basingstoke or St Denys)
• Southampton to Portsmouth and Havant (changeover at Havant)
  
• Havant to Ford & Bognor (changeover at Ford)
  
• Littlehampton to Arundel and Hove (changeover at Arundel or Hove)

...this in the east:

• Ebbsfleet/Gravesend to Sheerness & Faversham (changeover at Faversham)
  
• Faversham to Margate (changeover at Margate)
  
• Faversham to Dover Priory (changeover at Dover)
• Dover Priory to Margate and Minster (changeover at Dover or Minster)
  
• Ashford to Minster
  
• Ashford to Dover Priory
• Ashford to Hastings (changeover at Hastings)
• Hastings to Pevensey and West St. Leonards (changeover at West St. Leonards or Pevensey)
  
• Pevensey, Eastbourne and Seaford to Lewes (changeover at Lewes)
  
• Lewes to Brighton (changeover at Brighton for the depot)
  
• Lewes to Wivelsfield (changeover in two new outer platforms from the grade separation project)

...and that then leaves just the central mainlines, slowly working your way towards London. Havant to Guildford for changeover, Arundel to Warnham and Three Bridges for changeovers, Brighton to Three Bridges for changeover, etc.

 

[HSTEd]

And how many decades and how many tens of billions were you expecting to expend on this?

Almost all of the Southern region has stop spacings and traffic densities that make the advantages of >100mph marginal at best.

The third rail system functions and, for the most part, achieves what is asked of it.
The money would better spent on accelerating the programme of capacity upgrades that is apparently always running behind schedule.

 

[mr_jrt]

A simple incremental programme would be more than enough. The DC kit will need renewal at some point anyway. Do the design work now, when signalling is renewed do so so it's ready. Most of that you'd be paying for regardless. A few years out from the DC renewal date, start putting in the masts and doing any gauge enhancements needed. Then once you've prepared as much as you can, start working your way in, sticking any kit with useful working life left in it into storage for renewals of life-expired bits in more awkward areas. You'd be paying to renew the DC kit anyway, you're just moving some of the cost forward by a few years.

It's not all about faster speeds - you get better regenerative performance over larger sections, and you can deliver more current, enabling more and longer trains too. It's just a much better system.

 

[Railwaysceptic]

A simple incremental programme would be more than enough. The DC kit will need renewal at some point anyway. Do the design work now, when signalling is renewed do so so it's ready. Most of that you'd be paying for regardless.

There's the little matter of tunnels and overbridges which you would not be paying for regardless.

 

[Bald Rick]

What DC-only stock is still in use nowadays? All the Electrostar-deriviatives are dual voltage, as are the Siemens units, which is pretty much everything on the Southern region these days, so switching over isn't a big issue.

Most of the rolling stock operating on the D.C. network is D.C. only. Most of the electrostars and desirous are capable of being converted to AC, but they are missing transformers, cabling and various elements of the control system necessary to operate on AC. For the cost of converting them, given their remaining life, it would be cheaper to buy new.

It’s all irrelevant, anyway, as conversion of the D.C. Network isn’t going to happen in the remaining life of these trains.

 

[duffield]

Most of the rolling stock operating on the D.C. network is D.C. only. Most of the electrostars and desirous are capable of being converted to AC, but they are missing transformers, cabling and various elements of the control system necessary to operate on AC.
...

For older stock, would suitable/compatible items - particularly the control system elements even be available any more?

 

[Bald Rick]

For older stock, would suitable/compatible items - particularly the control system elements even be available any more?

You’d use new kit, like for the 455 traction upgrade.

 

[London Trains]

What DC-only stock is still in use nowadays?

Most of the stock is DC only, but it is capable of modifications to be AC.

However trains such as the 455s and 456s are not, but at least the SWR ones will be scrapped soon anyway.

 

[Meerkat]

Most of the stock is DC only, but it is capable of modifications to be AC.

However trains such as the 455s and 456s are not, but at least the SWR ones will be scrapped soon anyway.

Even if there was a conversion programme I reckon it would be a long long long time before it reached the inners

 

[mr_jrt]

There's the little matter of tunnels and overbridges which you would not be paying for regardless.

Well, yes. Some of those will have been dealt with for gauge enhancements for freight, which deals with those between Basingstoke and Southampton, leaving just the Bincombe Tunnel to cover off between Weymouth and Basingstoke, which appears to be generously-gauged, so hopefully shouldn't need much, if any, additional work. There are no tunnels between St Deny's and Hove, so that covers the west coastway off quite nicely. Overbridges are of course another matter, but following on from the GWML and MML projects, Network Rail have got those down pretty well, I think. Regardless, they can be done long before any conversion works need to happen as simple gauge enhancement as many are probably due for renewal anyway, and those works factor in OHLE clearances.

On the Kent side of things there are a fair few more tunnels, but I suspect nothing insurmountable. Fundamentally it's no different to electrifying a diesel line in that respect, it's just the western side of things would be relatively simpler to achieve so should probably be the starting point.

 

[HSTEd]

Anything gauge cleared before about 2010 is however likely to need to be cleared a second time given the changes in the regulations.

 

[klass43]

Most of the rolling stock operating on the D.C. network is D.C. only. Most of the electrostars and desirous are capable of being converted to AC, but they are missing transformers, cabling and various elements of the control system necessary to operate on AC. For the cost of converting them, given their remaining life, it would be cheaper to buy new.

It’s all irrelevant, anyway, as conversion of the D.C. Network isn’t going to happen in the remaining life of these trains.

If it's cheaper to buy new, why projects like class 769 and 230 conversions.

 

[Bald Rick]

If it's cheaper to buy new, why projects like class 769 and 230 conversions.

Because these two are conversions of existing electric trains to bolt on a diesel, which supplies electricity to existing kit. Notably neither of them involve installing large heavy transformers, racks of power electronics and HV cabling.

In any event, neither of the 2 classes are exactly setting the world on fire. (Or, Rather, one of them is, which is part of the problem).

 

[AM9]

... In any event, neither of the 2 classes are exactly setting the world on fire. (Or, Rather, one of them is, which is part of the problem).

And it looks like the impact of the epidemic might run for long enough for the 769s to not be introduced into service, especially in the North-west. TfW might be the main users of them.