Electrification at a terminus station

[TravisM]

At a large terminus station which has lines coming in from two different directions, one line having overhead catenary, would the whole station be wired up or just the platforms that brought the overhead lines into the station?

[Dagworth]

Probably only the platforms that can be accessed from the electrified lines. 
 

Andi

[ikcdab]

36 minutes ago, Dagworth said:

Probably only the platforms that can be accessed from the electrified lines. 
 

Andi

Obviously thats the right answer as there is no sense electrifying lines that can't be reached by electic locomotives.

However, taking it a step further,how is it decided what the layout will be. That is purely down to the traffic department who will decide on the timetable and what trains will run.That will dictate how many platforms are required by the electric services.

[Jeremy Cumberland]

Manchester Piccadilly famously had two different overhead electrification systems that were completely separate, even though (I think) non-electric trains could go from the ac side to the dc side and vice versa in both directions, and there are plenty of shared overhead/third rail stations where the different electrification systems are kept apart. The only example I can think of with both ac overhead and dc third rail is London Euston platforms 9 and 10 (apart from changeover points on Thameslink and Moorgate lines).

 

Obviously there is no point electrifying tracks that trains from the electric line could not reach, but apart from that I think the general principle was to electrify everything (unless it was particularly difficult), for ease of operating convenience. Wasn't pretty much all of Paddington was electrified when the Heathrow Express line was put in?

 

I can't think of any example where the end of an overhead electric railway joins a more important non-electrified line. Where this might have happened, such as the 1978 GNR electrification continuing to Cambridge, the usual practice seems to have been to truncate the electric line short (Royston), rather than spending lots of money electrifying a main station for a relatively minor service.

Edited April 10, 2023 by Jeremy C

[TheSignalEngineer]

1 hour ago, Jeremy C said:

Manchester Piccadilly famously had two different overhead electrification systems that were completely separate, even though (I think) non-electric trains could go from the ac side to the dc side and vice versa in both directions, and there are plenty of shared overhead/third rail stations where the different electrification systems are kept apart. The only example I can think of with both ac overhead and dc third rail is London Euston platforms 9 and 10 (apart from changeover points on Thameslink and Moorgate lines).

Manchester Oxford Road also had two systems for a while until the MSJ&A was converted to 25Kv.

Watford Junction has a section on the Down Fast to enable dual voltage units to be moved on and off the DC Lines.

[Wickham Green too]

1 hour ago, Jeremy C said:

... The only example I can think of with both ac overhead and dc third rail is London Euston platforms 9 and 10 (apart from changeover points on Thameslink and Moorgate lines). ...

... also various places where the CTRL interfaces  - or used to interface - with the Southern : Ebbsfleet, Ashford & Dollands Moor.

[25kV]

It would largely depend on how close to the terminus the two lines converged and, as others have said, what the operating requirements would be.  While Leeds (City) is not a terminus, when it was first electrified in 1988 or so, only the 'undercover' through platforms (and associated bays) were wired.  The terminating Aire Valley platforms remained unelectrified, as did the Trans-Pennine through platform and goods loops on the south side of the station as well as the parcels bays.  Later the whole station was wired with extensions to electrification in the area.  Interestingly a spur leading onto the old Holbeck viaduct was electrified in the initial wiring program, though later removed - and probably never used by an electric train in the meantime!  

[melmerby]

The Euston AC/DC lines extend as far as Camden where the 750v DC third rail route splits off to South Hamstead and eventually Watford and the AC continues as the Up & Down Slows.

There's another change at Kilburn High Road where the DC lines change from 750v DC third rail to 630v DC fourth rail, to suit the "tube" stock joining at Queen's Park.

[Wickham Green too]

Is there anywhere at Reading where a DC/AC changeover could be made ?

[The Stationmaster]

37 minutes ago, Wickham Green too said:

Is there anywhere at Reading where a DC/AC changeover could be made ?

Effectively no - but it could possibly be done on the unelectrified line between Reading East Jcn and Reading Southern Jcn if a train coasts downhill between the two systems and has a clear run at the bottom of the incline onto the 3rd rail area;  however i doubt if anyone would ever authorise that in this day & age.   The other link - Reading New Jcn to Reading Spur Jcn -  is fairly level and it too  isn't electrified on either system.

 

13 hours ago, jools1959 said:

At a large terminus station which has lines coming in from two different directions, one line having overhead catenary, would the whole station be wired up or just the platforms that brought the overhead lines into the station?

St Pancras International was initially planned for any train from any line to access a variety of platforms thus there was some spread of electrification onto what would otherwise be non-electrified lines and there would have been one shared platform which could handle either MML or CTRL trains.  However this was all cut out of the specification - after a lot of money had been spent on initial design estimates - in order to reduce the cost of rebuilding the station.

 

11 hours ago, Wickham Green too said:

... also various places where the CTRL interfaces  - or used to interface - with the Southern : Ebbsfleet, Ashford & Dollands Moor.

But these are/were really no more than changeover locations because whichever way you are going a train which can only run on one of the systems will run out of juice once it leaves its own supply system.

 

Another example is between Mitre Bridge/sire of North Pole Jcn and the Westway overbridge on the West London Line which was (and probably still is? ) dual electrified on the south side of the GWML.   Basically a traction changeover arrangement but the dual powered section is quite long.

[45655]

11 hours ago, melmerby said:

There's another change at Kilburn High Road where the DC lines change from 750v DC third rail to 630v DC fourth rail, to suit the "tube" stock joining at Queen's Park.

Presumably the fourth rail is bonded to the running rails on this section (and there is a train length dead section for tube stock at the transition) as the DC lines stock is third rail only.

 

Another Keith

Alton.

[russ p]

I know of a couple of oddities platform 6 at Norwich isn't wired and neither is platform 4 at York. 

One of the first 91 hauled trains into York was actually signalled into it and the locomotive de wired resulting in damage I believe 

[Grovenor]

18 hours ago, Jeremy C said:

Manchester Piccadilly famously had two different overhead electrification systems that were completely separate, even though (I think) non-electric trains could go from the ac side to the dc side and vice versa in both directions, ....

 

Obviously there is no point electrifying tracks that trains from the electric line could not reach, but apart from that I think the general principle was to electrify everything

 

I can't think of any example where the end of an overhead electric railway joins a more important non-electrified line.

Go back to when it was Manchester London Rd. Then the platforms serving the ex LNW lines were not electrified but those few on the East side serving the ex GC were electrified at 1500V DC and the lines serving the Althincham lines on the West side were also 1500V Dc but there was no provision for through running between the two 1500V Dc lines.  I would say the general principle was to wire up what was needed.

Surely the London Rd example was very much the end of an overhead electrified railway (well two of them) joining a more important non-electrified line, ie the West Coast Main line.

[Michael Hodgson]

19 hours ago, Jeremy C said:

I can't think of any example where the end of an overhead electric railway joins a more important non-electrified line. Where this might have happened, such as the 1978 GNR electrification continuing to Cambridge, the usual practice seems to have been to truncate the electric line short (Royston), rather than spending lots of money electrifying a main station for a relatively minor service.

Cambridge and Royston are of course both through stations.  As the gaps beyond Royston to Cambridge and beyond Hitchin to Peterborough (also a through station but the commuter terminus) weren't wired in the 1970s, but some of the commuter service had to serve them there had to be diesel hauled trains as well and DMU shuttles until the wires were extended decades later.  This combination was presumably operationally a bit less efficient and more expensive than just using one form of traction.  The practice of stabling two electric trains in each platform at Royston overnight must have been inconvenient as it removed the GNR Cambridge route from the ECML diversionary options; at least Hitchin had a stabling siding for that DMU.

[Compound2632]

10 hours ago, Wickham Green too said:

Is there anywhere at Reading where a DC/AC changeover could be made ?

 

Per @Stationmaster's reply. But in addition, there's no dual-system electric stock for miles around. I'm not sure even Voyagers work through that way to Brighton any more?

[Compound2632]

22 hours ago, Jeremy C said:

I can't think of any example where the end of an overhead electric railway joins a more important non-electrified line. Where this might have happened, such as the 1978 GNR electrification continuing to Cambridge, the usual practice seems to have been to truncate the electric line short (Royston), rather than spending lots of money electrifying a main station for a relatively minor service.

 

I hadn't known that had been the case - my travels to Cambridge started after the GE route had been electrified, though I always went from Kings Cross. But equally, I only recently discovered that the Hitchin - Cambridge line hadn't been Great Northern all the way to Shelford Junction but only to a point about a mile east of Shepreth station, the remainder being Great Eastern.

[Peter Kazmierczak]

23 hours ago, Jeremy C said:

Obviously there is no point electrifying tracks that trains from the electric line could not reach, but apart from that I think the general principle was to electrify everything (unless it was particularly difficult), for ease of operating convenience. Wasn't pretty much all of Paddington was electrified when the Heathrow Express line was put in?

 

 

I think it was platforms 3 - 11 which were initially electrified at Paddington, though HEX generally only used 6 & 7. Of course, platforms 15 & 16 were also on the juice, but as part of the Hammersmith & City line.

[jim.snowdon]

9 hours ago, 45655 said:

Presumably the fourth rail is bonded to the running rails on this section (and there is a train length dead section for tube stock at the transition) as the DC lines stock is third rail only.

 

Another Keith

Alton.

Correct, as far as the negative rail bonding is concerned, but the Watford DC Lines are still only 650V on account of the limitations of 1972 tube stock, which cannot cope with 750V (and was never designed to, unlike some later LU stocks).

[jim.snowdon]

1 hour ago, Compound2632 said:

 

Per @Stationmaster's reply. But in addition, there's no dual-system electric stock for miles around. I'm not sure even Voyagers work through that way to Brighton any more?

Virtually all modern electric stock is capable of dual voltage operation, essentially because the control equipment operates on DC. The GWR's 387s are even equipped with shoegear, normally strapped up, and did some of their early testing on the Brighton Line. The problem is not engineering the AC/DC changeover, but managing the differences between an AC system that has earthed running rails and a DC system where the rails are intentionally not earthed, as well as the issues affecting the signalling equipment, although that problem is disappearing with the general adoption of axle counters in place of track circuits.

[Compound2632]

3 minutes ago, jim.snowdon said:

Virtually all modern electric stock is capable of dual voltage operation, essentially because the control equipment operates on DC. The GWR's 387s are even equipped with shoegear, normally strapped up, and did some of their early testing on the Brighton Line. 

 

I am now better informed. Mrs Compound will be pressing for electrification of the connecting link at Reading along with the Oxford line once the Nuneham Viaduct is repaired, with direct Earley - Oxford trains.

[melmerby]

1 hour ago, Compound2632 said:

 

I am now better informed. Mrs Compound will be pressing for electrification of the connecting link at Reading along with the Oxford line once the Nuneham Viaduct is repaired, with direct Earley - Oxford trains.

Didcot to Oxford was part of the GWML electrification but AFAIK has been completely dropped. Everything's based on Bi-mode these days

Shame really as that could've help push the E-W rail to be electrified, as then the MK - Oxford service could be pure electric stock.

[phil-b259]

4 hours ago, Michael Hodgson said:

 This combination was presumably operationally a bit less efficient and more expensive than just using one form of traction. 

 

But it saved the need to fit a new electric substation at  Cambridge and resigned the later!

 

What people often forget is that you don't put substations at each end of electrification schemes - they are done on a 'star' configuration with lots of stub ends! of course on a larger scheme or where a second scheme buts onto the first two of those stub ends are connected,  but if you are only doing a single scheme having stub ends is bay far the most efficient way of doing it.

 

Thus with the GN scheme Royston was as far as they could reasonably get without the need for an extra substation (Royston being a stub fed from Hitchin)  extension onwards towards Cambridge would have to wait for Cambridge to get done as part of its own scheme - which NSE duly did in the late 1980s.

[phil-b259]

3 hours ago, Compound2632 said:

 

Per @Stationmaster's reply. But in addition, there's no dual-system electric stock for miles around. I'm not sure even Voyagers work through that way to Brighton any more?

 

As has been discussed MANY times before the Voyagers are fundamentally unsuited to any form of electric traction because they lack the all important HV bus line running the length of the set! Any attempts to replace / supplement the diesel engines is thus a non starter as the coasts of completely re-wiring the units is a non starter half way through their design life.

 

The 800 series units however were designed form the outset to be hydrids so have far more scope to mix power sources and more importantly this can be done at pretty much any point in their service life

 

And as for Voyagers running to Brighton - that stopped around 15-20 years ago now!

[Compound2632]

6 hours ago, phil-b259 said:

As has been discussed MANY times before the Voyagers are fundamentally unsuited to any form of electric traction

 

You misunderstand me - I was merely saying that as things stand only diesel units can work through. But that doesn't happen, except for service moves - the Gatwick turbos run from the Waterloo platforms.

[Edwin_m]

19 hours ago, 45655 said:

Presumably the fourth rail is bonded to the running rails on this section (and there is a train length dead section for tube stock at the transition) as the DC lines stock is third rail only.

The gap only needs to be one coach long.  Main line units have a bus cable linking the shoes within the unit, but tube stock only links the shoes on an individual car.