Great Western Main Line electrification - ongoing discussion

[whole diary]

[TonyK]

Alas, the article has hidden behind a paywall. Presumably Tranche 0 should be first?

To quote my son, who tends to be rather direct: Yes, that's how numbers work!

I am again indebted.

I can access the MR^▸ (Midland Railway) article intermittently - sometimes the paywall blocks it, sometimes it doesn't.

So far, no good. I'll try on my phone when it has some electrification of its own.

The article refers to Tranch 0 as the 'Hendy tail' - schemes removed from GWEP^▸ (Great Western Electrification Program) following the review of the CP5^▸ (Control Period 5 - the five year period between 2014 and 2019) enhancements by Network Rail Chair Sir Peter Hendy:

The strategy notes that electrification from Chippenham to Bristol can utilise spare capacity in the feeder station at Thingley and could cut journey times by up to 2.5 minutes. On Filton bank (Bristol Parkway to Temple Meads), the potential for South Wales to Bristol EMUs^▸ (Electric Multiple Unit) is noted, as are the environmental benefits of decarbonisation in an urbanised area.

Labelling this 'Tranch 0' does sort of imply that it should have happened already. MR says the NR^» (Network Rail - home page) report describes these schemes as ‘mature’, with power supply in place and signalling immunised in readiness for electrification.

Is the shaving of 2.5 mins off journey times really a key selling point though? I would have thought the environmental benefits would be an easier sell...

I agree entirely, especially with Bristol's new clean air zone in operation. That said, whilst I can manage the extra 2.5 minutes when travelling from 'Nam to Temple Meads wityhout noticing, that sort of margin could be significant in terms of schedules for other services.

[Electric train]

The re-signalling of the ECML^▸ (East Coast Main Line) has been in development for a number of years, projects like the dive under at Peterborough, Kings Cross remodelling even the Hitchin flyover are all part of the bigger plan.   The ECML was re-signalled South of Hitchin in the early 1970's for the Electrification the rest of the ECML re-signalling follow fairly quickly after that, so it is at the end of its life.   There are lot of issues with the existing signalling equipment, wire insulation degradation, silver migration in relays and general obsolescence  

What's "silver migration in relays"?

When an electrical circuit with inductance (a coil for instance), is broken, the current drops suddenly. The inductance therefore tries to oppose this by producing a large inverse voltage. This is sufficient to cause a spark across opening contacts. At such high energies small particles of the (silver alloy) metal surface are transferred with the spark. You can see this also in a traditional car ignition system. Over years of frequent operation even highly rated railway relay contacts therefore start to lose their initial shape, producing some resistance between them when closed.

ISTR^▸ (I seem to recall/remember) that railway policy was to replace them every 21 years but condition monitoring was not used, so heavily used ones were not changed any more often than lightly used ones. Modern practice is to use more solid state devices and to use strategies such as "Zero volt/current switching" in ac circuits.

Our esteemed ET member could give a clearer more precise description.

OTC

Not certain that this is correct. Contact wear in relays is undoubtedly a problem as described above, it may be reduced in various ways.
SILVER MIGRATION is however a different phenomena. It is an electrolytic process whereby in the presence of traces of moisture, silver is dissolved to form ions, which then migrate under under an electric field, and form metallic silver in some place other than the original location of the original silver contact.
This can result in maloperation, and in extreme cases even in a wrong side failure of signaling.

Silver migration is the result of a DC^▸ (Direct Current) voltage, it wont occur on AC circuits.
It may be reduced by physically larger equipment with greater clearances, and by excluding damp.
It may be eliminated by not using silver contacts.

Contact wear from sparking has been known about since the very beginning of the electrical age, well over 100 years ago.

Silver migration was not recognised until the 1950s, and not fully understood until some years after that.

Railway signaling schemes that use miniature relays are vulnerable.

Silver migration is an electrolysis process where the sliver plating on the relay contacts migrates from contact to the other contact this increases the electrical resistance of the contacts due to oxidisation, can lead to burning of the contact faces all this has can lead to wrong side failures.

 

[onthecushions]

I promised that ET would have the final and best word!

OTC

[stuving]

This Wales and Western Regional Traction Decarbonisation Strategy is now available on that link, but only if you are logged on as a user of RailUKForums. It was liberated by a rather rapid FoI request.

[ChrisB]

Surely FOI^▸ (Freedom of Information) requests ,make documents PUBLIC? Not to be restricted to just some members of the public?

[grahame]

This Wales and Western Regional Traction Decarbonisation Strategy is now available on that link, but only if you are logged on as a user of RailUKForums. It was liberated by a rather rapid FoI request.

Surely FOI^▸ (Freedom of Information) requests ,make documents PUBLIC? Not to be restricted to just some members of the public?

Hmmm ... we do similar on the Coffee Shop.  Our achieve holds around 1,000 indexed .pdf files (and others that need indexing) but only 100 are whitelisted.  It's not that the other 900 are not out there in public - it's just that with the complexity of copyrights, etc, I only authorise something in public from a web site I manage if I'm certain that I'm allowed to.

Edit - you fill find lots of Decarbonisation Strategy stuff in our members archive -
http://www.firstgreatwestern.info/research.html?search=decarbonisation+strategy

[stuving]

Just over a year ago we were puzzling over the significance of this line item in the "National Infrastructure and Construction Pipeline":

PS (edit) Also line 418 "Reading Independent Feeder"

That spreadsheet identified* the funding profile for that as:
Status August 2021:    "planning and consents"
2021/22: £M27.3    2022/23:  £M25.4   2023/24:  £M5.6
Due in service 2023.

So, it should be half done by now, yes? Well, not so far as the view from space shows it, but National Grid are just getting into their stride with digging holes and (no doubt) trucking transformers. This is their announcement of the works, mainly for the benefit of the neighbours:

Project overview

To support Network Rail to reinforce, future-proof, and decarbonise its electrical network, earlier this year, National Grid began work to install a Supergrid transformer at Bramley substation and connect it to a new trackside feeder station at Holly Cross.

Construction work began in April 2022 with completion expected in mid-2023.

Project update - Road closure – Oliver’s Lane, Bramley 9 January 2023 – 1 February 2023
20th December 2022 - Infrastructure

National Grid is continuing work to connect Bramley substation to a new trackside feeder station near Oliver’s Lane.

The next stage of work will involve the building of a temporary construction road, then to dig a trench and install cables. Oliver’s Lane in Bramley will be closed from Monday 9 January 2023 – Wednesday 1 February 2023 in order to ensure work can be carried out safely and efficiently.

Letters were distributed to residents in Bramley informing them of the planned works on Wednesday 14 December. 

There will be no access through Oliver’s Lane for the entire duration of the works, including nights and weekends.

Advanced notice signs will be put in place and the diversion route is detailed in the map below. The closures and traffic management has been agreed with the local Highways Authority.

Some of the other text does rather lay it on with a JCB about decarbonising the world, when this project is really about providing robustness to the electric railway.

* It's a record of government departments' allocated funding, not a policy document the allocates funds itself.

[stuving]

While looking back at this thread I was reminded of this odd-looking concept: "A fully automated net positive submarine fleet, powered entirely on green hydrogen...". At the time we were rather taken with green submarines, but this time I'm baffled by "net positive". What does (or should) that - and the rarely used net negative - mean? Well, here's an explanation from the Low Carbon Hub (and what could be more up-to-date than a hub?) - those of a logical disposition should probably look away now:

What is carbon positive / negative?  

Carbon negative or positive mean the same thing and are simply an add-on to being carbon neutral. 

[Noggin]

Just over a year ago we were puzzling over the significance of this line item in the "National Infrastructure and Construction Pipeline":

PS (edit) Also line 418 "Reading Independent Feeder"

That spreadsheet identified* the funding profile for that as:
Status August 2021:    "planning and consents"
2021/22: £M27.3    2022/23:  £M25.4   2023/24:  £M5.6
Due in service 2023.

So, it should be half done by now, yes? Well, not so far as the view from space shows it, but National Grid are just getting into their stride with digging holes and (no doubt) trucking transformers. This is their announcement of the works, mainly for the benefit of the neighbours:

Project overview

To support Network Rail to reinforce, future-proof, and decarbonise its electrical network, earlier this year, National Grid began work to install a Supergrid transformer at Bramley substation and connect it to a new trackside feeder station at Holly Cross.

Construction work began in April 2022 with completion expected in mid-2023.

Project update - Road closure – Oliver’s Lane, Bramley 9 January 2023 – 1 February 2023
20th December 2022 - Infrastructure

National Grid is continuing work to connect Bramley substation to a new trackside feeder station near Oliver’s Lane.

The next stage of work will involve the building of a temporary construction road, then to dig a trench and install cables. Oliver’s Lane in Bramley will be closed from Monday 9 January 2023 – Wednesday 1 February 2023 in order to ensure work can be carried out safely and efficiently.

Letters were distributed to residents in Bramley informing them of the planned works on Wednesday 14 December. 

There will be no access through Oliver’s Lane for the entire duration of the works, including nights and weekends.

Advanced notice signs will be put in place and the diversion route is detailed in the map below. The closures and traffic management has been agreed with the local Highways Authority.

Some of the other text does rather lay it on with a JCB about decarbonising the world, when this project is really about providing robustness to the electric railway.

* It's a record of government departments' allocated funding, not a policy document the allocates funds itself.

AIUI^▸ (as I understand it) National Grid have a 5-year lead time on feeder stations. Transformer was delivered in September 2022, apparently held up by low river levels in Germany.

https://www.nationalgrid.com/electricity-transmission/infrastructure-projects/bramley-network-rail/latest-news/new-transformer-arrives-bramley

From what I can see, the idea is that it mainly provides redundancy for maintenance etc, but doubtless it does provide extra capacity and once it's in place I suppose that NR^» (Network Rail - home page) can more confidently extend electrification, particularly west from Newbury. 

One question is how it will feed into the GWML^▸ (Great Western Main Line), seems like it could need an awfully long extension cable but wasn't it Market Harborough where NR decided it was more cost effective to just extend MML^» (Midland Main Line. - about) electrification, so perhaps they might do that?

Looking at this optimistically, a lot of things seem to be coming to fruition that would enable the "Hendy Tail" to be completed at reasonable cost.

[Bmblbzzz]

While looking back at this thread I was reminded of this odd-looking concept: "A fully automated net positive submarine fleet, powered entirely on green hydrogen...". At the time we were raher taken with green submarines, but this time I'm baffled by "net positive". What does (or should) that - and the rarely used net negative - mean? Well, here's an explanation from the Low Carbon Hub (and what could be more up-to-date than a hub?) - those of a logical disposition should probably look away now:

What is carbon positive / negative?  

Carbon negative or positive mean the same thing and are simply an add-on to being carbon neutral. 

"LOL^▸ (laughing out loud)" and "AAAAAAAAAGH"!

This reminds me of a joke from Hitchhiker's Guide to the Galaxy, where, having made God disappear in a puff of logic, man goes on to prove that black is white and white is black; then gets himself killed on the next zebra crossing.

However... perhaps in this case negative is positive because a net removal of carbon from the atmosphere is a positive thing? Whether it's a possible for a submarine to effect a net removal of carbon seems doubtful to me, but that's a separate issue.

[stuving]

AIUI^▸ (as I understand it) National Grid have a 5-year lead time on feeder stations. Transformer was delivered in September 2022, apparently held up by low river levels in Germany.

https://www.nationalgrid.com/electricity-transmission/infrastructure-projects/bramley-network-rail/latest-news/new-transformer-arrives-bramley

From what I can see, the idea is that it mainly provides redundancy for maintenance etc, but doubtless it does provide extra capacity and once it's in place I suppose that NR^» (Network Rail - home page) can more confidently extend electrification, particularly west from Newbury. 

One question is how it will feed into the GWML^▸ (Great Western Main Line), seems like it could need an awfully long extension cable but wasn't it Market Harborough where NR decided it was more cost effective to just extend MML^» (Midland Main Line. - about) electrification, so perhaps they might do that?

Looking at this optimistically, a lot of things seem to be coming to fruition that would enable the "Hendy Tail" to be completed at reasonable cost.

Ah - the picture I was looking at was from November 2011, not 2022, hence the lack of visible progress. But this was always going to be needed once GWML electrification was committed to, well over five years ago. At the start it was part of the Electric Spine project, then it was rescued from the sinking of that and lumped in with the Thames Valley branches, and when they were taken out of scope it was put in its own little project because it is still needed.

With no Electric Spine*, it needs its own wires to the Reading ATFS. I have a vague memory that was to take the form of three wires on poles along the line, and the same applied to the similar link from Thingley Junction ATFS to Royal Wootton Bassett ATFS. But in that case it was run in conduit all the way, so this one may be too.

The NG^▸ (Natural Gas) words refer to one transformer, which is unlike all the other OLE^▸ (Overhead Line Equipment, more often "OHLE") feeds that have two. I presume that is because this is a back-up to a back-up, and not to be used permanently for its capacity. Standard design rules for power distribution require that every component (including connecting cables) can be taken out of use without loss of anyone's supply.

* It's possible that a separate interconnector was always intended, even with OLE in place along the route. Otherwise, it's hard to see why Reading and Royal Wootton Bassett are labelled as ATFS, as neither has any other power input. There is another such link - the Welsh Independent Feeder - from Newport (St Brides ATFS, near Imperial Park NG) to Cardiff (Canton ATFS). But in that case of course the OLE is installed.

[Electric train]

One question is how it will feed into the GWML^▸ (Great Western Main Line), seems like it could need an awfully long extension cable but wasn't it Market Harborough where NR^» (Network Rail - home page) decided it was more cost effective to just extend MML^» (Midland Main Line. - about) electrification, so perhaps they might do that?

It will be a cable route alongside the railway to Reading ATFS.  The distribution Voltage is 25-0-25kV effectively 50kV.   The main purpose is to allow Reading and the Berks n Hants becoming an island, especially Reading Train Care Facility, in the event of a double outage Didcot and Kensal Green which is has come close to happening, also with Cross Rail the capacity at Kensal is limited in the event one of the Grid transformers there being out of service

If the supply had been put in for the "Spine" then there would have been 2.

The commissioning of 400kV transformer is long process and commissioning a new Grid site on to the railway is not a quick process even onto an already electrified railway.  Testing will need to be done on the line to Basingstoke to check there is no compromise to signalling and rise in Earth potential under normal and fault conditions 

[Trowres]

DfT^» (Department for Transport - about) has publised a report by Systra, evaluating the outcomes of the Great Western Route Modernisation programme. It's scope extends beyond electrification.


https://assets.publishing.service.gov.uk/government/uploads/system/uploads/attachment_data/file/1166248/great-western-route-modernisation-first-post-opening-evaluation-final-report.pdf

I will leave others to comment...

[FarWestJohn]

More waffle.

[Electric train]

More waffle.

That's as as may be ..........

However politicians, policy influencers, DfT^» (Department for Transport - about) etc will use this report to support their particular objective regarding railway electrification for many years to come