Electrification system islands.

[plugwash]

I started wondering about "islands" of electrification, where a line or small group of lines is electrified with a given system, but is not connected to the main area that uses that system.

There are two major electrification systems in the UK, 25KV overhead and 750V third rail.

25KV is used on the ECML, the WCML, HS1 , the southern portion of the MML, the eastern portion of the GWML, the northern part of thameslink and various branches/suburban lines connected to those mainlines.750V is mostly used in the area south of London.

Looking at my trackatlas (2018 edition I think, don't have it in front of me riggh), It seems that the ECML, WCML and HS1 all have electrified connections between them at the London end, The northern part of Thameslink joins in to both the ECML and the MML, so all of these lines are linked.

There seem to be several islands of 750V, a couple in north london (the Watford DC line and part of the northern city line), merseyrail in liverpool and of course the isle of wight.

At least according to my 2018 trackatlas the GWML seems to be an island of 25KV. At the London end It comes very close to and is even crossed by other 25KV lines, but the connection between them seems to be non-electrified, is this still the case?

are there any other such islands.

 

[Ianno87]

Merseyrail is something of an "island" of third rail.

 

[Gloster]

The Isle of Wight is an island in the sense that it is an actual, physical island, but all the nearby lines are to the same voltage; go south and the first ones you hit are 25 kV. I believe that the current is controlled from the mainland, possibly Eastleigh.

 

[Halish Railway]

Although not major, the Rotherham Tram-train line with 750 V DC wiring and parts of the Network Rail maintained network in the Northeast have 1.5 KV DC wiring, both constituting as electrification islands.

 

[zwk500]

At least according to my 2018 trackatlas the GWML seems to be an island of 25KV. At the London end It comes very close to and is even crossed by other 25KV lines, but the connection between them seems to be non-electrified, is this still the case?

The link between the GWML and the WCML/WLL at Acton is not wired, but the GWML will be connected to the GEML 25kv through Crossrail. I'm not sure if that's currently live, or if you were thinking of open lines only.

 

[Watershed]

There is currently no AC link from the MML to the rest of the AC electrified network, nor from the GWML. In both cases there is an unelectrified chord to the North London Line. In both cases it's less than a mile of wiring that's missing.

Whilst the GWML will be linked to rest of the electrified network by Crossrail once it opens, it's difficult to envisage through running of anything other than Crossrail or (at a push) engineering trains. And whilst Thameslink gives the MML an electrified link to the rest of the network, it only does so on 750V DC.

 

[zwk500]

There is no AC link from the MML to the rest of the AC electrified network, nor from the GWML. In both cases there is an unelectrified chord to the North London Line. In both cases it's less than a mile of wiring that's missing.

Not quite - as the OP pointed out, the OLE-Equipped Thameslink lines connect at St Pancras Thameslink to the OLE-Equipped ECML via Canal Tunnels.

 

[Mag_seven]

Swansea Maliphant IET depot is wired at 25kv AC and not connected to anything else due to the decision to cancel Cardiff - Swansea electrification.

 

[Ianno87]

Not quite - as the OP pointed out, the OLE-Equipped Thameslink lines connect at St Pancras Thameslink to the OLE-Equipped ECML via Canal Tunnels.

Prior to the Canal Tunnels, the MML was an AC island (the short track connection to HS1 at St Pancras isn't electrified).

 

[zwk500]

Prior to the Canal Tunnels, the MML was an AC island (the short track connection to HS1 at St Pancras isn't electrified).

Indeed - I took the OP to be asking about current Islands, not ones that were bridged 3 years ago. The status of Crossrail bridging the gap to the GWML is open to debate.

 

[Watershed]

Not quite - as the OP pointed out, the OLE-Equipped Thameslink lines connect at St Pancras Thameslink to the OLE-Equipped ECML via Canal Tunnels.

True, but the restrictions on its use (including the need to reverse in the Core) are so onerous as to prevent its use for most non-conventional purposes. But yes, technically it's not an island.

 

[ANDREW_D_WEBB]

Prior to being connected to the GWML was North Pole an island of 25kv?

Old Dalby test track is an island of (IIRC) 25kv, 750 dc and LUL style 4th rail. I believe there is similar at Litchurch Lane, Derby.

Waterloo and City Line has been an isolated island of electrification on both BR and London Underground.

 

[zwk500]

True, but the restrictions on its use (including the need to reverse in the Core) are so onerous as to prevent its use for most non-conventional purposes. But yes, technically it's not an island.

Yes, operationally it's not feasible. It makes the announcement about OLE being descoped from EWR even more frustrating.

Prior to being connected to the GWML was North Pole an island of 25kv?

North Pole was on the very edge of the OLE for NLL/WCML/WLL. However, it was not possible to run AC-Only trains into or out of North Pole without a reversal at North Pole Jn.

 

[Mag_seven]

Prior to being connected to the GWML was North Pole an island of 25kv?

Well now that you come to mention North Pole there is still a connection to the West London Line and there are wires at that connecting point so maybe the GWML isn't actually isolated at all?

 

[snowball]

Swansea Maliphant IET depot is wired at 25kv AC and not connected to anything else due to the decision to cancel Cardiff - Swansea electrification.

Maliphant has stanchions and gantries for wiring but the last I heard it didn't have any actual wires.

 

[zwk500]

Well now that you come to mention North Pole there is still a connection to the West London Line and there are wires at that connecting point so maybe the GWML isn't actually isolated at all?

It appears that yes, the GWML is not an island although as with Crossrail and the MML at Thameslink, it's not much use to passenger trains.

On a slight tangent, at Reading there is no electrified connection between the AC and DC systems.

 

[themiller]

The Tyne & Wear metro is wired down the Durham coast from Pelaw to Sunderland creating an island of 1500V DC on NR metals.

 

[Mag_seven]

Maliphant has stanchions and gantries for wiring but the last I heard it didn't have any actual wires.

My mind might be playing tricks on me as it has been quite a while since I've been down that way but I'm sure I saw wires there!

 

[snowball]

There were no wires when the Streetview car was there in June 2019.

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I haven't been to Swansea since 1993 but I remember the absence of wires being mentioned on here two or three years ago.

 

[Greybeard33]

On a slight tangent, at Reading there is no electrified connection between the AC and DC systems.

Likewise, at Allerton there is no electrified connection between the AC WCML and the Merseyrail DC line to Hunts Cross. The 25kV overrun from Allerton Junction terminates before the DC line joins the CLC line at Hunts Cross West Junction. An AC electrified headshunt from Allerton Depot runs alongside the Merseyrail track for some distance, but there is no crossover between them.

Best to avoid AC and DC electrification of the same track where possible, to avoid grounding/stray current issues.

 

[Bald Rick]

There is currently no AC link from the MML to the rest of the AC electrified network, nor from the GWML. In both cases there is an unelectrified chord to the North London Line. In both cases it's less than a mile of wiring that's missing.

Being extremely pedantic, whilst there is a link between the MML and North London Line, it’s 4 miles long, and not a ‘chord’.

 

[snowball]

Likewise, at Allerton there is no electrified connection between the AC WCML and the Merseyrail DC line to Hunts Cross. The 25kV overrun from Allerton Junction terminates before the DC line joins the CLC line at Hunts Cross West Junction. An AC electrified headshunt from Allerton Depot runs alongside the Merseyrail track for some distance, but there is no crossover between them.

Best to avoid AC and DC electrification of the same track where possible, to avoid grounding/stray current issues.

My 2013 Quail/Trackmaps map shows a little bit of purple (dual electrified track) in the Allerton/Hunts Cross area.

 

[Greybeard33]

My 2013 Quail/Trackmaps map shows a little bit of purple (dual electrified track) in the Allerton/Hunts Cross area.

2013 was before the re-electrification of Allerton Depot for Northern's 319s. The track layout was changed at that time. I think there used to be an eastern exit from the depot towards Hunts Cross, that crossed the DC track. That was changed to a segregated 25kV headshunt with new OLE masts and wiring.

The original WCML OLE used to extend further towards Hunts Cross on the CLC main line than it does now, past Hunts Cross West Junction, so at that time the junction was indeed dual electrified. The old masts, minus wires, are still in place for a short distance west of the junction on the Merseyrail line, where there used to be a 25kV overrun.

 

[LNW-GW Joint]

The WCML and ECML are of course linked via several wired routes in Scotland, originally with Edinburgh-Carstairs (there are now several alternative routes).
The WCML is linked to HS1 via the NLL and a chord into St Pancras (via a single Eurostar platform) - never used as far as I can tell.

 

[matchmaker]

The Glagow subway is the only 3rd rail system in Scotland.

 

[zwk500]

The WCML is linked to HS1 via the NLL and a chord into St Pancras (via a single Eurostar platform) - never used as far as I can tell.

I believe the triangle was used, ironcially by a diesel train, when the Orient Express did a PR stunt for the Murder on the Orient Express film

 

[SargeNpton]

Likewise, at Allerton there is no electrified connection between the AC WCML and the Merseyrail DC line to Hunts Cross. The 25kV overrun from Allerton Junction terminates before the DC line joins the CLC line at Hunts Cross West Junction. An AC electrified headshunt from Allerton Depot runs alongside the Merseyrail track for some distance, but there is no crossover between them.

Best to avoid AC and DC electrification of the same track where possible, to avoid grounding/stray current issues.

Slows lines out of Platforms 9 & 10 at Euston to Primrose Hill Tunnel seem to have managed okay for the last 50+ years.

 

[AlistairCowell]

The North Clyde Line running from Helensburgh / Balloch / Milngavie to Springburn / Airdrie via Glasgow QS Low Level was a 25kv AC island until 1979, when the Argyle Line re-opened that links with electrified Lanarkshire suburban lines and the WCML.

Before the WCML was electrified between Crewe and Glasgow in May 1974, Cathcart Circle and Inverclyde Lines were also an electrified island.

In fact, there were two electrified railway islands in Glasgow!

Manchester to Bury line back in its BR days was also an electrified island, but it wasn’t majorly a big deal as it used the unique side contract 1200v DC 3rd Rail. The trains were Class 504 two-car EMU. This was the line became part of the Manchester Metrolink in 1992.

 

[Tom Quinne]

Swansea Maliphant IET depot is wired at 25kv AC and not connected to anything else due to the decision to cancel Cardiff - Swansea electrification.

Not any more, the depot was fully wired ready to plug into the Mainline scheme only to be dewired later.

 

[paul1609]

I believe the triangle was used, ironcially by a diesel train, when the Orient Express did a PR stunt for the Murder on the Orient Express film

I don't think there are any locos that are fitted with the KVB signalling system fitted in St Pancras (HS1). I believe one of the freight operating companies has a safety case exemption to allow its class 66 to work there without protection under special protection for special purposes. I think that any traction unit/ mu going from HS1 to the UK electrification systems has to have a system for selecting different heights of the overhead wire between the two systems.