GWML Electrification progress: Newbury-Reading B&H section

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swtandgw

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It's been a while since I've posted on the forums (I've been busy with other commitments), but I've noticed something whilst I was taking some spring cleaning down to the new Padworth recycling facilities. Since the bridge by Aldermaston station has been closed off for works, I was wondering if electrification work has already commenced? I've not yet seen OHLE appear on the line, but I think it looks like they're starting off with taking care of bridge clearances first.
 
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themiller

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It's been a while since I've posted on the forums (I've been busy with other commitments), but I've noticed something whilst I was taking some spring cleaning down to the new Padworth recycling facilities. Since the bridge by Aldermaston station has been closed off for works, I was wondering if electrification work has already commenced? I've not yet seen OHLE appear on the line, but I think it looks like they're starting off with taking care of bridge clearances first.
This is normal practice so that the teams installing the OHLE have a straight run at it (especially as the plain line work is to be done using the HOOP train. The idea is to complete the civil (concrete and shovel) work before the expensive electrical (masts and wires) part.
 

HSTEd

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Once the wiring train goes to work it will be over in a matter of a couple of months, so it will likely be the last thing on the list.
 

John55

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This is normal practice so that the teams installing the OHLE have a straight run at it (especially as the plain line work is to be done using the HOOP train. The idea is to complete the civil (concrete and shovel) work before the expensive electrical (masts and wires) part.
While it does vary from route to route it is probably wrong to assume the wires and masts are the expensive bit. The UK has very high numbers of over bridges and tunnels along railway lines which can be very expensive to modify or replace and the costs of providing a bulk supply point can be astronomical and then there is the cost of work to the signaling system if that needs replacement or immunisation.
 

swtandgw

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Also, wouldn't they have to make preparations on where the transformer stations/feeders/neutral sections are going to go? I probably think that might be the next step before the HOOP train starts the wiring work, although I don't know as I'm not familiar on how previous large-scale electrification projects work.
 

swt_passenger

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Isn't Basingstoke 3rd rail? How does that mesh with high voltage overhead?
You'd just need a suitable changeover section with both supplies overlapping. Standard technology as is seen on Thameslink and at various points on the NLL and WLL.

The only debate is really how complex you make it, which is why it is often suggested that it is better to do the changeover on the branch at a place where all trains stop, rather than in a multiplatformed station like Basingstoke with complex junctions at both ends.

Like in the ongoing discussion about Reading, it might be less complex to changeover in the single track eastern underpass, rather than in X number of platforms.
 

jopsuk

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Much of Ashford International is dual voltage too- served by some OHL-only stock these days (Eurostars have all lost their 3rd rail shoes since St Pancras Int opened). Also dual voltage on the high level platforms at Ebbsfleet, and before HS1 was completed, Eurostars were able to change on the move on a long section from just south of Ebbsfleet onto the 3rd rail network. Obviously some dual voltage sections near Dollands Moor for Channel tunnel freight, and there's Drayton Park on the Moorgate line. Dual voltage sections aplenty!
 

ole man

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Change of location, Sydney Gardens in Bath has to be the best unspoilt area to watch all kinds of traction.

What will happen when this area gets OLE, will we be subject to the ugly pallaside fencing, and over the top safety measures?
 

Kentish Paul

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Yes, platforms 5 and 6 at Ashford International are the changeover points for C395 from OH to 3rd rail. Takes about 30 secs. Faringdon is the Thameslink changeover point.
 

atillathehunn

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I'm sorry this isn't strictly on the topic of the GWML electrification, but this seems to have devolved into a discussion on voltage changes which makes this somewhat relevant.

It is quite straight forward, it seems, to change from 3rd rail DC to overhead AC, but how complicated is it to change voltages within an entirely overhead system? In all the many train journeys I have taken around Europe and the world I'm sure it has happened on a train I have been on, but I clearly wasn't paying attention at that point (can't say the overhead equipment is my primary source of interest on a journey!). Does a diesel shunter come and change you from one platform to another which has the correct voltage overhead, or can you have different systems operating in the same platform and you have a small 'last mile home' diesel engine which allows you to shunt forward into the new section? Probably should put the beer down and pay more attention in the future!

Hope this made sense...
 

Nym

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You can just install some clever power electronics on the roof that detect the source and changeover automatically, potentially at speed by use of neutral sections.
 

transmanche

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You can just install some clever power electronics on the roof that detect the source and changeover automatically, potentially at speed by use of neutral sections.
We used to have changeover between 6.25kV AC and 25kV AC on the fly; on the GEML, LTS and around Glasgow.
 

Nym

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We used to have changeover between 6.25kV AC and 25kV AC on the fly; on the GEML, LTS and around Glasgow.
Yup, that's surprisingly simple by using tap changing relays, a baseline rectifier and a solenoid selector.

Use a small transformer to step down to something sensible, pass it through a coil, rectified if you like, and then have a solenoid in this coil that controls your switchover relays on the tap changer for the main transformer.

And if you're running with a tap changer by default, even more simple, jyst integrate it into the Power Controller.
 

LNW-GW Joint

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It is quite straight forward, it seems, to change from 3rd rail DC to overhead AC, but how complicated is it to change voltages within an entirely overhead system? In all the many train journeys I have taken around Europe and the world I'm sure it has happened on a train I have been on, but I clearly wasn't paying attention at that point (can't say the overhead equipment is my primary source of interest on a journey!). Does a diesel shunter come and change you from one platform to another which has the correct voltage overhead, or can you have different systems operating in the same platform and you have a small 'last mile home' diesel engine which allows you to shunt forward into the new section?
TGVs do it all the time on the move from Paris Gare de Lyon (on DC) to reach the LGV SE (on AC), then again when they leave the LGV to reach eg Lyon/Marseille/Dijon etc on DC again.
And again approaching Brussels on every Thalys service (and yet again to reach Amsterdam/Cologne).
It's no problem.
Same in Italy...Spain... The old network is DC and high speed lines are AC.
Eurostars do it like TGVs approaching Brussels, Avignon and the Alps.
Siemens ICEs do the same leaving Germany for Belgium and France.
 

atillathehunn

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Thanks all for the replies. Didn't think it was that easy to do! From the journeys you listed I must be on a train that changes the voltage really rather frequently and have never noticed.
 

L&Y Robert

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We used to have changeover between 6.25kV AC and 25kV AC on the fly; on the GEML, LTS and around Glasgow.
Now you come to mention it, wasn't the very first AC electric main line Manchester-Crewe? I remember now, reading then, that the overhead was energised at a lower AC voltage in the urban area because of the proximity of structures, trees and wot not. The full 25kv was only applied "Out in the country". Another point about it was that the early overhead apparatus on this line contained a "stitch wire", that is, an intermediate wire between the catenary, and the contact wire. I note that modern installations do not contain a stitch wire, and the support arms are at ashallower angle than they were at first. Learning from experience, is it?
 

ole man

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That wire is called auxillary catenary, and is still used on RBS2 Stafford - Bushbury Junction, and a few other places that havent been upgraded to UK1 style OHLE
 

ole man

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It was MK1 Equipment that had Auxillary Catenary wire.

To achieve either of these higher speeds, the auxiliary wire will be removed from Mark I OLE at the same time as the contact wire and all the droppers are renewed. The catenary wire will not be replaced, even at 225 km/h, because there are no dynamic changes. This simplifies the upgrade, because unlike the contact and auxiliary wires, the catenary wire passes over rather than under the portal structures typically used on four-track sections.

The cross-section of the hard-drawn copper-silver contact wire will be increased from 105 to 120mm2 in order to accommodate the rise in tension from 10 to 14 kN. This will also offset the loss of conductivity in the former auxiliary wire.

Another important modification that applies to Mark III as well as Mark I OLE is replacement of the cantilevered registration arms - this is already in progress north of Weaver Junction. The new, lighter assembly using aluminium tube and polymeric insulators has a haunched profile, which allows the pantograph greater uplift. The contact wire stagger will be reduced to minimise the risk of dewiring


Taken from Railway Gazette.
 

Monty

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Which is a shame since it further reduces the number of dmu's required to operate service around Reading & the Thames Valley
It would make more sense to lay down the third rail on that line plus a small section at Reading itself. That way the branch could be worked by SWT and the route used for diversions during engineering works.
 

swt_passenger

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It would make more sense to lay down the third rail on that line plus a small section at Reading itself. That way the branch could be worked by SWT and the route used for diversions during engineering works.
It is explicitly down for AC in the NR electrification RUS as a part of the XC routes - the problem is that they will already have OHLE between Reading Station and Southcote Jn (for the B&H) by the time the line down to Basingstoke is to be electrified. Running DC into Reading from the west on all the various routes that will exist after the remodelling would be pretty complex and probably unnecessary. Also, AC electrification fits in with starting back Reading to Paddington peak busters at Basingstoke, as discussed in the London and SE RUS.

I also see that a recent post in wnxx suggests Basingstoke wiring may be sooner than expected...
 

fgwrich

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Three bridges in the Aldermaston area are being raised
And making a pretty good job of it apparently, with what was supposed a similar job to the bridge clearances on the Waterloo - Salisbury line, now involving a complete bridge rebuild at Aldermaston as the original abutments now apparently couldn’t take the weight.

As for the electrification, i still think it's a shame that its only going as far as Newbury, as yes there’s some nice countryside between Newbury and Bedwyn, but most of the through services Newbury gets are the Bedwyn services, So really the only diesel operated services it will eliminate is the Reading to Newbury shuttle, usually worked by a 2 car 165.
 

swt_passenger

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As for the electrification, i still think it's a shame that its only going as far as Newbury, as yes there’s some nice countryside between Newbury and Bedwyn, but most of the through services Newbury gets are the Bedwyn services, So really the only diesel operated services it will eliminate is the Reading to Newbury shuttle, usually worked by a 2 car 165.
But as some of us have discussed at length before, the service patterns following electrification could be completely diffferent, as is explained in the GW RUS.

The Bedwyn terminators could easily be replaced by additional through services, such as stops by the additional (bimode IEP operated) Taunton semifasts.
 

LE Greys

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It is explicitly down for AC in the NR electrification RUS as a part of the XC routes - the problem is that they will already have OHLE between Reading Station and Southcote Jn (for the B&H) by the time the line down to Basingstoke is to be electrified. Running DC into Reading from the west on all the various routes that will exist after the remodelling would be pretty complex and probably unnecessary. Also, AC electrification fits in with starting back Reading to Paddington peak busters at Basingstoke, as discussed in the London and SE RUS.

I also see that a recent post in wnxx suggests Basingstoke wiring may be sooner than expected...
I'd expect that the Reading bay at Basingstoke will be a.c. Depending on whether they would want changeover platforms specifically (remembering that XC will probably use electro-diesel traction on diesel mode) then most likely the wires would run into two out of four through platforms. Alternatively, run third rails up the branch for a couple of block sections to allow 92s etc. to change over on the move. Two questions though. Would e-Voyagers be able to start up on the move? Will whatever their replacement is be capable of d.c. operation? I suppose they could fit the Voyagers with shoes as well, but that would just make the arrangement even more complicated and add cost for a comparatively short distance, Basingstoke-Poole is not that far.
 

turbo mick

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The bridges in the aldermaston area should have been complete in May but due to structuring issues will be complete in september its been giving grief to us locals who normally use for road access
 

DXMachina

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Can't see dual-voltage voyagers happening - apart from anything else going over 90mph on 3rd rail is problematic and over 100 extremely difficult (Unless you're a 4-REP running light, re recent posts)

Voyagers would lose the most useful 35mph of their speed capacity through running on 750v. Even without the problem that their traction motors need a higher voltage than that
 
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