Discontinuous electrification schemes should be replaced by continuous electrification

[Lawner]

That's what I meant. I understand they use PTFE-coated non-conducting contact rods in neutral sections to provide the sliding characteristics needed.

In many cases a low over-bridge will not have clearance to allow sufficient gap between the pantograph and the structure, and between the pantograph and the vehicle. But a non-conducting contact wire or rod that could push the pan down enough to achieve mechanical clearance would be enough not to have to rebuild the bridge.

Provided that all electric stock on the line had a traction battery with sufficient range to self-rescue a stranded train, I still don't see why neutral sections longer than two train lengths cannot be used to save the cost of rebuilding low bridges when appropriate to do so.

In the case where mechanical clearances are achievable then the use of surge diverters and insulating coating should get the wire through the bridge whilst keeping it energised.

Rail engineer have an article on the technology I'm talking about.

Overcoming the clearance issue - Rail Engineer

Listen to this article Whilst third rail and other low-level current collection systems add a lot of equipment to a railway at ground level, the general approach to electrification across the world has involved the adoption of overhead contact systems. In the UK, the early schemes tended to...

www.railengineer.co.uk

There might be a few hints here:-

Signed, an industry source (who has actually done some of this stuff).

Having been responsible and a budget holder for track maintenance in the past, I can confirm that the changes to track maintenance costs from electrification are there on paper…. But not on steel, ballast and concrete. It doesn’t reduce inspection frequencies, nor tamping frequencies or the rate of track faults. The cost changes are essentially negligible in the whole scheme of things,

and an electrification business case (Which I have also been responsible for writing).

Sounds as though Bald Rick has a lot of experience from which to make his statements. As an observer of this particular discussion, I'm wondering if you have anything similar on your CV, or, like me, are just an lay observer?

Oh, and a reminder that IW didn't mention the Cardiff Valleys discontinuous electrification once in the article you cited as evidence. As the only such scheme well under way, I find it curious that he didn't reference it at all, as it would have been the obvious thing to do.

As I have already said, I've worked in the industry for years with a lot of that in electrification. It's not reasonable to just say somethings wrong or saying you disagree without any expansion or evidence. Why Walmsley didn't mention the valleys I don't know but it isn't immune to the issues he has raised. I could bring up issues I've heard about the project through conversation but obviously it's better to use publicly available, reliable sources as this is an anonymous forum.

 

[JKF]

How many routes converted wholly to light rail in the UK can you name that have subsequently converted back to heavy rail?

East London Line?

 

[Nottingham59]

In the case where mechanical clearances are achievable then the use of surge diverters and insulating coating should get the wire through the bridge whilst keeping it energised.

Rail engineer have an article on the technology I'm talking about.

Overcoming the clearance issue - Rail Engineer

Listen to this article Whilst third rail and other low-level current collection systems add a lot of equipment to a railway at ground level, the general approach to electrification across the world has involved the adoption of overhead contact systems. In the UK, the early schemes tended to...

www.railengineer.co.uk

I have taken a keen interest in the Cardiff bridge insulation, but that article contains new information, so thank you for the reference. And of course if you can get under a bridge with energised catenary using insulated bridge coatings and surge suppresors, then you should do that.

But as the article says, you still need 20mm above the wire and 70mm between pan and the train body. The point I'm trying to make it that you could do better than Cardiff if necessary:

• You don't need the insulating coating which is at least 3-4 mm thick
• unenergised non-conducting slider rods can be fixed to the bridge itself, giving you another 19mm. You might need more than one slider if the bridge is arched.
• the slider rod can be wider across and thinner vertically, giving you 5 mm or so
• the pan can be even closer to the train body if it is de-energised, giving you up to 69mm more. (provided the neutral section is longer than the train, so that even trains with a high-voltage bus and two pans, like class 395 Javelins, can pass safely.

But to do this successfully, any EMUs will need a traction battery of some sort to self-rescue, if they ever get trapped in the extend neutral section. I've not seen any sign that NR have looked at this possibilty for electrifying the very lowest bridges.

 

[stuu]

East London Line?

That has never been light rail

 

[JKF]

That has never been light rail

What do we class underground as? It went from heavy rail to that (arguably both for a while when freights were still running) then back to heavy rail. Sort of analogous to light rail at least.

 

[eldomtom2]

The Underground is heavy rail by most definiitions. If "heavy rail" is taken to mean "mainline only", then it's a metro/subway.

 

[stuu]

What do we class underground as? It went from heavy rail to that (arguably both for a while when freights were still running) then back to heavy rail. Sort of analogous to light rail at least.

The underground is heavy rail, it has no characteristics of light rail at all: no low platforms, sharp corners, lighter track/structures. The A Stock trains used when it was part of the Underground were the widest trains in the whole country

 

[Bald Rick]

What is your basis for saying Walmsley is wrong?

In short, because a lot of people have spent a lot of time investigating this subject. Obviously I can’t go into too much detail. I’ll leave it there.