Discontinuous Electrification - RUK's thoughts?

[eldomtom2]

I recently read a Garry Keenor thread on Mastodon where he is severely critical of the idea of discontinuous electrification, particularly as a method of avoiding having to raise clearances. What are RUK's thoughts on discontinuous electrification? Does it have a place?

 

[Lucy1501]

I believe the South Wales metro project will be using this in places, so yes, it evidently does have a place.

 

[GRALISTAIR]

I don't like discontinuous electrification but economic reality etc has forced us into this situation. Bridge and tunnel clearance is a huge cost so I understand why it is being considered.

 

[waterboo]

Midland Metro tramway extensions also have discontinuous electrification.

 

[Energy]

Earthed overhead wire has been mostly superseded by insulating paint, which similarly reduces electrical clearances to be below mechanical clearance but without the need for on board batteries.

Discontinuous electrification with the pan dropping before bridges is unrealistic, and bridge swaps aren't particularly expensive.

Using batteries to extend services beyond wires however does have a place.

Garry Keenor's threads are excellent and very informative but he does also have a vested interest since he works in electrification at Atkins.

 

[snowball]

Earthed overhead wire has been superceded by insulating paint, which similarly reduces electrical clearances to be below mechanical clearance but without the need for on board batteries.

Discontinuous electrification with the pan dropping before bridges is unrealistic, and bridge swaps aren't particularly expensive.

Using batteries to extend services beyond wires however does have a place.

Garry Keenor's threads are excellent and very informative but he does also have a vested interest since he works in electrification at Atkins.

Apart from the fact that the word is superSeded, I think your first sentence is an exaggeration. If it were true, it would mean that insulating paint is a better choice than earthed overhead wire at every location. But as I understand it, earthed overhead wire is being used at several places on the Core Valley Lines.

 

[Energy]

Apart from the fact that the word is superSeded, I think your first sentence is an exaggeration. If it were true, it would mean that insulating paint is a better choice than earthed overhead wire at every location.

No solution is perfect for every location, though I'm struggling to think of a situation in which earthed OHLE is suitable but insulating paint isn't.

But as I understand it, earthed overhead wire is being used at several places on the Core Valley Lines.

Indeed, though the design work for the core valley lines would have been done years ago, before insulating paint was well proven on the Severn Tunnel.

 

[MarkyT]

No solution is perfect for every location, though I'm struggling to think of a situation in which earthed OHLE is suitable but insulating paint isn't.

One on routes where all the trains will have at least some battery capacity fitted, which I think will be expedient on many future fleets to manage power demand and provide operational resilience for isolations, both planned and emergency.

Indeed, though the design work for the core valley lines would have been done years ago, before insulating paint was well proven on the Severn Tunnel.

I'm sure the project would have reconsidered changing this if expedient during the construction cycle. The new stock needed batteries for through working onto network rail infrastructure that, for now, is not planned to be wired.

 

[Nottingham59]

No solution is perfect for every location, though I'm struggling to think of a situation in which earthed OHLE is suitable but insulating paint isn't.

One of the problems is that an insulated layer applied to the underside of a bridge makes it much more difficult to inspect that bridge for corrosion or other structural damage.

 

[snowball]

Indeed, though the design work for the core valley lines would have been done years ago, before insulating paint was well proven on the Severn Tunnel.

Wasn't it the Cardiff intersection bridge, not the Severn tunnel, where the insulating paint was used? A metal structure. Has insulating paint been used for non-metal structures?

 

[RailWonderer]

A lot of the Victorian infrastructure does not lend itself to electrification and in some places new lines would have to be built so discontinuous is a lot more pragmatic.

Battery tech will improve and regional battery units are operating relatively successfully on the continent so it’s a matter of time before the UK follows suit. It’s all progress.

 

[43074]

A lot of the Victorian infrastructure does not lend itself to electrification and in some places new lines would have to be built so discontinuous is a lot more pragmatic.

That claim clearly doesn't stand up to scrutiny when some of the oldest Intercity railways in the world (Euston to Birmingham, Liverpool to Manchester via Chat Moss, Great Western to Cardiff) are all electrified.

The only reason discontinuous electrification is seen as more pragmatic is because of the cost of electrification, that is why it has been used on the Valley Lines for instance.

 

[Snow1964]

That claim clearly doesn't stand up to scrutiny when some of the oldest Intercity railways in the world (Euston to Birmingham, Liverpool to Manchester via Chat Moss, Great Western to Cardiff) are all electrified.

The only reason discontinuous electrification is seen as more pragmatic is because of the cost of electrification, that is why it has been used on the Valley Lines for instance.

At the moment, freight is not using electric locos in Wales. Of course historically most of those lines were built to carry coal.

If you start operating electric heavy freight on them there you are going to get serious coupling snatching, or having to trundle along coasting if the wire has lots of dead sections.

How far the solution is pragmatic to get line part done, vs a longer term full decarbonisation where subsequently need to back and sort a bit other bits to make it fully electric is still to be seen.

 

[GRALISTAIR]

The only reason discontinuous electrification is seen as more pragmatic is because of the cost of electrification, that is why it has been used on the Valley Lines for instance.

Exactly.

 

[Nottingham59]

I recently read a Garry Keenor thread on Mastodon where he is severely critical of the idea of discontinuous electrification, particularly as a method of avoiding having to raise clearances. What are RUK's thoughts on discontinuous electrification? Does it have a place?

Gary K is saying that a BEMU fleet will cost twice that of a purely electric fleet. I find that very hard to believe.

 

[Kingston Dan]

Midland Metro tramway extensions also have discontinuous electrification.

I was in Brum a couple of months ago and noticed this - why wouldn't you just wire down places like Broad Street?

 

[snookertam]

Am I right in saying the Paisley Canal branch beyond Corkerhill is discontinuous electrification - hence why it went up so quickly?

 

[Bald Rick]

I was in Brum a couple of months ago and noticed this - why wouldn't you just wire down places like Broad Street?

Why would you if batteries are cheaper?

 

[Dr Hoo]

I was in Brum a couple of months ago and noticed this - why wouldn't you just wire down places like Broad Street?

I can accept that Broad Street itself isn't much of an architectural gem but buildings like the Hall of Memory, Baskerville House, the Town Hall and the Council House are a bit more iconic. The original electric tram network didn't run via this area either. Once you've got batteries you may as well use them a bit further - Wolverhampton Station for example.

(Statement of personal interest - I was born and brought up in Birmingham.)

 

[fishwomp]

I recently read a Garry Keenor thread on Mastodon where he is severely critical of the idea of discontinuous electrification, particularly as a method of avoiding having to raise clearances. What are RUK's thoughts on discontinuous electrification? Does it have a place?

It has a place, but limited. At one point there was horror at electrifying the Royal Border bridge at Berwick, because of it's beauty, and daft ideas like gaps and coasting..

Couldn't we describe Bristol or Cardiff -Swansea as discontinuous electrification.. there is no reason to assume battery as the other power source.. Penzance, sure it's already electrified.. just discontinuously.

Ideally rationality would return to clearance requirements - much higher than historical but yet electrity is the same as it always has been, and alternatives like the paint would also be deployed. Then there can be cheaper, lighter rolling stock and the job considered done.

 

[Falcon1200]

Am I right in saying the Paisley Canal branch beyond Corkerhill is discontinuous electrification - hence why it went up so quickly?

Depends what is meant by discontinuous! There are a couple (I think) of low bridges where, to avoid the cost of rebuilding, short dead sections were installed instead, but the line is wired throughout and battery-fitted EMUs are not necessary.

 

[HSTEd]

It is all very well to complain about discontinuous electrification, but the reality is the railway has utterly failed to deliver the "proper" electrification that it desires at reasonable cost.

 

[Trainbike46]

The way I see it, both continuous and discontinuous electrification have a role to play. At current rates, continuous electrification will take too much time, especially if it is the only tool we would be using. What is needed is:
- More electrification located to maximise the reduction in diesel use, considering the option of using BEMUs
- New BEMUs to take over from DMUs that reach end of life (the 150s, are getting near that point, and the other sprinters aren't that far behind. And apparently the 16x fleets may need to be replaced as well)
-Where DMUs need replacing but (B)EMUs aren't currently suitable, use cascaded DMUs or expedite works that would make BEMUs suitable. Build no more new diesel stock.

 

[6Gman]

A lot of the Victorian infrastructure does not lend itself to electrification and in some places new lines would have to be built so discontinuous is a lot more pragmatic.

Battery tech will improve and regional battery units are operating relatively successfully on the continent so it’s a matter of time before the UK follows suit. It’s all progress.

We have a fair amount of electrification and I'm struggling to think of many examples of new lines having to be built.

In fact, Harecastle Tunnel is the only example to immediately come to mind.

Any other examples?

 

[Dr Hoo]

Woodhead Tunnel was an obvious one. I think that Thurgoland needed a new bore too.
Penmaenshiel Tunnel tragically collapsed during track lowering (albeit for taller containers initially) and had to be replaced with a deviation.
Farnworth Tunnel had to be filled with concrete and then re-bored, so effectively ‘new’.

 

[Magdalia]

We have a fair amount of electrification and I'm struggling to think of many examples of new lines having to be built.

In 1983 Clapton tunnel was closed for three weeks while the track was lowered to provide increased clearances for the OHL to be converted from 6.25kV to 25kV. New line was built, but it was moved vertically not horizontally!

 

[willgreen]

That claim clearly doesn't stand up to scrutiny when some of the oldest Intercity railways in the world (Euston to Birmingham, Liverpool to Manchester via Chat Moss, Great Western to Cardiff) are all electrified.

it may have made them more expensive, though - and that cost will inevitably damage the business case of wiring less intensively used lines.

 

[RailWonderer]

We have a fair amount of electrification and I'm struggling to think of many examples of new lines having to be built.

In fact, Harecastle Tunnel is the only example to immediately come to mind.

Any other examples?

The Hope Valley and the Valley lines in Wales. I never said a new line would have to be built, precisely it wouldn't given the prohibitive cost.

 

[6Gman]

The Hope Valley and the Valley lines in Wales. I never said a new line would have to be built, precisely it wouldn't given the prohibitive cost.

Where have they had to build new lines (or opted for discontinuous) in the Valleys for electrification?

Of lines currently being discussed as electrification projects a deviation might end up being necessary at Christleton if Crewe-Chester was wired.

 

[Ken H]

1. Discontinuous electrification will mean that the main circuit breaker will operate more. It may need a higher spec and or become a maintenance liability. I am sure there will be other stressed components to consider.
2. We have lots of bi modes - electric and diesel. If most of the route is electric then running a diesel engine for the unwired bit may be cost effective. Voyager replacement would be electric/diesel bimodes because there would be some heroic unwired stretches for a BEMU, I think.
BUT, the rail industry should not make it too easy for government to wriggle out of wiring our network properly. The best solution is routes fully wired so we can have simple electric trains with no diesel or battery power supply.