Great Western Electrification Progress

GRALISTAIR · 21 Oct 2016

GazK said:
If the forum can hold on about a month I will be publishing a free ebook on the subject which is more comprehensive, factually correct and importantly has been written and peer-reviewed by electrification engineers. Give me a prod mid November if a link hasnt appeared here.

Outstanding - I look forward to clicking on the link and reading it when ready as I am sure many on here will too.

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jimm · 22 Oct 2016

GazK said:
My point was that they are not called tension arms, and thats because their purpose is not to provide tension. They are there to register the contact wire, i.e. provide horizontal restraint. Hence "registration".

A simple mistake on my part after a series of very long, tiring days compounded by a series of missed connections getting me home 60 to 90 minutes later than planned each time as well. I have previously referred to registration arms back up the thread and will try to remember to do so in future...

themiller · 22 Oct 2016

GRALISTAIR said:
Outstanding - I look forward to clicking on the link and reading it when ready as I am sure many on here will too.

I'll second that.

HowardGWR · 22 Oct 2016

Thanks. I found the Baxter report very helpful, however amateurly produced. GazK's 'ebook' will be appreciated of course.

How does the sub-station at Melksham (of all places) get the juice to the GWML? It is south of the real GWML at Chippenham, although the said juice will initially be required at Somerford and the Branch from Dauntsey is no more.

LNW-GW Joint · 22 Oct 2016

HowardGWR said:
How does the sub-station at Melksham (of all places) get the juice to the GWML? It is south of the real GWML at Chippenham, although the said juice will initially be required at Somerford and the Branch from Dauntsey is no more.

http://www2.nationalgrid.com/UK/In-your-area/Projects/melksham-gwm-connections/

To make the connection in Melksham, we will use 25kV underground cables to carry the electricity. Two lines of cables will run from the existing National Grid substation off Westlands Lane and connect to the railway further north at Thingley Junction.

The connection will take around a year to install and work will be carried out in sections. The cables will be laid down into trenches within a working area about 20m wide. To go under streams along the route, the cables will be drilled horizontally underground as a small tunnel, rather than laid into trenches. When the work is complete, we’ll return the land to how it looked before

GazK · 22 Oct 2016

HowardGWR said:
Thanks. I found the Baxter report very helpful, however amateurly produced. GazK's 'ebook' will be appreciated of course.

How does the sub-station at Melksham (of all places) get the juice to the GWML? It is south of the real GWML at Chippenham, although the said juice will initially be required at Somerford and the Branch from Dauntsey is no more.

There's a set of buried supply cables which run along the alignment of the HV pylon route from Melksham to Thingley. They did that because the wayleave already exists and it was easier than getting planning permission for a new tap-off pylon at Thingley.

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swt_passenger · 22 Oct 2016

HowardGWR said:
How does the sub-station at Melksham (of all places) get the juice to the GWML? It is south of the real GWML at Chippenham, although the said juice will initially be required at Somerford and the Branch from Dauntsey is no more.

The National Grid facility at Melksham (just to the northwest to be accurate) is a significant pre-existing site, and not actually related to the presence of the railway at Melksham.

So the electrification grid supply is named for the distribution network end of the link, not its physical position on the railway, as the link posted earlier shows.

HowardGWR · 22 Oct 2016

swt_passenger said:
The National Grid facility at Melksham (just to the northwest to be accurate) is a significant pre-existing site, and not actually related to the presence of the railway at Melksham.

So the electrification grid supply is named for the distribution network end of the link, not its physical position on the railway, as the link posted earlier shows.

Thanks. I still find it difficult to imagine there being no connection on the Badminton route. Mr Baxter's diagram shewed nothing between Wales and Didcot (by implication) on that route, as of course Thingley is on the Chippenham route, the true 'GWML'.

How far apart do these substations need to be? I would have thought one at Filton, say, would have been required.

swt_passenger · 22 Oct 2016

HowardGWR said:
Thanks. I still find it difficult to imagine there being no connection on the Badminton route. Mr Baxter's diagram shewed nothing between Wales and Didcot (by implication) on that route, as of course Thingley is on the Chippenham route, the true 'GWML'.

How far apart do these substations need to be? I would have thought one at Filton, say, would have been required.

The OHLE guide suggests substations are 'about' 60 km apart, Didcot - Melksham is only marginally further in a straight line, so each substation is having to reach about 30 km either side of itself. So the Melksham substation connection at Thingley will cover the distances required along the Badminton route from both ends as it is all a connected system, the benefits of the auto transformer feeder system allow the substations to be further apart than on a traditional installation anyway.

PHILIPE · 22 Oct 2016

Severn Tunnel done. Re-opened today.

GRALISTAIR · 22 Oct 2016

PHILIPE said:
Severn Tunnel done. Re-opened today.

When you say done does that mean it is wired and everything? Obviously not energized but ....

GazK · 22 Oct 2016

swt_passenger said:
The OHLE guide suggests substations are 'about' 60 km apart, Didcot - Melksham is only marginally further in a straight line, so each substation is having to reach about 30 km either side of itself. So the Melksham substation connection at Thingley will cover the distances required along the Badminton route from both ends as it is all a connected system, the benefits of the auto transformer feeder system allow the substations to be further apart than on a traditional installation anyway.

There will be a pair of 25kV feeder cables running from Thingley Feeder Station to Wootton Bassett Feeder Station, so that Wootton Bassett is able to feed the Badminton lines. These "independent feeders" are currently being installed - look out for the light grey troughing being laid out between Chippenham and WB.

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HowardGWR · 22 Oct 2016

GazK said:
There will be a pair of 25kV feeder cables running from Thingley Feeder Station to Wootton Bassett Feeder Station, so that Wootton Bassett is able to feed the Badminton lines. These "independent feeders" are currently being installed - look out for the light grey troughing being laid out between Chippenham and WB.

Ah, I'm there now, thanks. I didn't realise there was to be one at WB. The diagram I saw had nothing between Cardiff and Didcot via Badminton.

Some of the replies made me wonder whether some were unaware that there were two parallel widely-separated railway lines from WB to Bristol.

edwin_m · 22 Oct 2016

themiller said:
I'll second that.

Thirded (?). Is one of the errors the suggestion that neutral sections switch themselves from one supply to the other as the train passes through?

GazK · 22 Oct 2016

edwin_m said:
Thirded (?). Is one of the errors the suggestion that neutral sections switch themselves from one supply to the other as the train passes through?

Yes it is. I think that they were intending to describe the function of a carrier wire neutral section, which will be installed for the first time on GW. However there is no switching involved, the train is simply transferred from PS1 onto a non-energised wire run and then back onto PS2. They talked to a number of OLE engineers before writing the report but looks like it got lost in translation.

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PHILIPE · 22 Oct 2016

GRALISTAIR said:
When you say done does that mean it is wired and everything? Obviously not energized but ....

Obviously not energised yet but structures in place

D1009 · 22 Oct 2016

Does the conductor bar come outside the tunnel?

GazK · 22 Oct 2016

D1009 said:
Does the conductor bar come outside the tunnel?

No it stops just inside. When the conventional wiring is installed at the tunnel mouth the transition arrangement will be added between the two.

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--- old post above --- --- new post below ---

D1009 said:
Does the conductor bar come outside the tunnel?

See the photo here:

https://twitter.com/FurrerFreyGB/status/788429970737692672

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swt_passenger · 22 Oct 2016

GazK said:
There will be a pair of 25kV feeder cables running from Thingley Feeder Station to Wootton Bassett Feeder Station, so that Wootton Bassett is able to feed the Badminton lines. These "independent feeders" are currently being installed - look out for the light grey troughing being laid out between Chippenham and WB.

That still suggests to me that Wooton Bassett is fed from the Melksham grid supply, just that there are additional 25 kV supplies running to that location alongside but separate to the overhead system.

Or is there a separate grid supply AT Wooton Bassett?

GazK · 22 Oct 2016

swt_passenger said:
That still suggests to me that Wooton Bassett is fed from the Melksham grid supply, just that there are additional 25 kV supplies running to that location alongside but separate to the overhead system.

Or is there a separate grid supply AT Wooton Bassett?

You're right, there isnt. But it means that the Badminton lines can be fed independently of the Chippenham line, so you can have one route out for maintenance and keep running trains on the other.

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swt_passenger · 22 Oct 2016

GazK said:
You're right, there isnt. But it means that the Badminton lines can be fed independently of the Chippenham line, so you can have one route out for maintenance and keep running trains on the other.

Thanks, that makes it clearer. The reason I ask is that there is a description of something called the "Bramley independent feeder" in the CP5 enhancement plans, and AIUI that has two possible options, one is a supply from Didcot, and the other is a separate grid supply?

I think there's a risk of terminology confusion, i.e. a feeder station isn't the same as a substation or grid supply point?

GazK · 22 Oct 2016

swt_passenger said:
Thanks, that makes it clearer. The reason I ask is that there is a description of something called the "Bramley independent feeder" in the CP5 enhancement plans, and AIUI that has two possible options, one is a supply from Didcot, and the other is a separate grid supply?

I think there's a risk of terminology confusion, i.e. a feeder station isn't the same as a substation or grid supply point?

Bramley grid supply will be south of Reading, on the Basingstoke line. Completely different site, but would have the same independent feed to Reading AT site.

A feeder station is a site that has an incoming supply, either from the national grid or from another feeder station via independent feeders. The word substation tends to be used as a generic term meaning either a feeder station or an auto transformer site. A grid supply point is the national grid location feeding the railway.

Its all very confusing I agree.

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HowardGWR · 23 Oct 2016

GazK said:
Bramley grid supply will be south of Reading, on the Basingstoke line. Completely different site, but would have the same independent feed to Reading AT site.

A feeder station is a site that has an incoming supply, either from the national grid or from another feeder station via independent feeders. The word substation tends to be used as a generic term meaning either a feeder station or an auto transformer site. A grid supply point is the national grid location feeding the railway.

Its all very confusing I agree.

Hopefully this further question is not leading to an answer that you plan to give anyway in what you will kindly make for us in November.

Where is the neutral section between South Wales feeder station (was it Cardiff IIRC?) and Wootton Bassett on the Badminton line? Do these sections define the 'border', as it were, between such feeders?

smiffy9373 · 23 Oct 2016

All posts now up on Maidenhead viaduct.

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leomartin125 · 24 Oct 2016

smiffy9373 said:
All posts now up on Maidenhead viaduct.

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Are they the same round posts they used on the viaduct just outside Goring & Streatley?

Quark999 · 24 Oct 2016

First wires up on main and relief through Taplow station as well. Just one direction each.

smiffy9373 · 24 Oct 2016

leomartin125 said:
Are they the same round posts they used on the viaduct just outside Goring & Streatley?

They look similar. Not sure as it was dark on my runs past last night.

snowball · 24 Oct 2016

No doubt there'll be pictures of the Maidenhead bridge in the magazines soon.

Meanwhile, a volley of press releases about the Severn Tunnel works:

http://www.networkrailmediacentre.c...les-mainline-for-electrification-is-completed

http://www.networkrailmediacentre.c...re-opens-to-rail-passengers-following-upgrade

http://www.networkrailmediacentre.c...tunnel-electrification-project-are-from-wales

http://www.networkrail.co.uk/News/2...es-Mainline-for-electrification-is-completed/

HowardGWR · 24 Oct 2016

snowball said:
No doubt there'll be pictures of the Maidenhead bridge in the magazines soon.

Meanwhile, a volley of press releases about the Severn Tunnel works:

http://www.networkrailmediacentre.c...les-mainline-for-electrification-is-completed

http://www.networkrailmediacentre.c...re-opens-to-rail-passengers-following-upgrade

http://www.networkrailmediacentre.c...tunnel-electrification-project-are-from-wales

http://www.networkrail.co.uk/News/2...es-Mainline-for-electrification-is-completed/

Amazed how clean the brickwork was after the 'de-sooting' they did.

D1009 · 25 Oct 2016

Anyone know any details of what was done in the Patchway tunnels?

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