Should the third rail ban be lifted?

[swt_passenger]

On the national Network in seperate projects with seperate justifications (AIUI), there are at least the following:

East London Line from Shoreditch to Dalston Junction and New Cross Gate flyover
East London Line from Dalston Junction to Highbury & Islington
East London Line from Silwood Jn to Old Kent Road Jn
Three Bridges Depot - access lines and sidings

Examples on the underground too - Northern extension, Jubilee extension, T5 extension etc.


Uckfield and Ashford - Ore are ideal for batteries too.

Eastleigh ‘up freight loop’ (as it was originally described), but also used by up stopping passenger services, is relatively minor in length but shows a new third track added alongside the existing lines would be powered by third rail.

I’d always assumed any sensible three or four tracking of existing routes would be allowed third rail as a matter of course.

 

[JonathanH]

That may be, but the issue is also one of principle - replacing the current DMU fleets with restricted use sub-fleets is a seriously sub-optimal way of resourcing these lines. The objective should be to have a common fleet, and benefit from the economies of scale that supported the NSE & Scotrail 1980s electrifications.

How does it differ from Southern having eight 377/7s for three West London Line diagrams?

 

[35B]

How does it differ from Southern having eight 377/7s for three West London Line diagrams?

Operationally - it doesn't.

The real difference is that a compromise has to be made because it joins two pre-existing electrified networks, which means that a compromise is necessary to allow the service to run. For Uckfield or Romney Marsh, there would be a specific decision to embed that inflexibility in the long term where there is an option to avoid that.

 

[zwk500]

Would a BEMU obtain sufficient charge between London and Hurst Green to run to Uckfield and back? If not, an extension of sufficient length to recharge would be necessary, in which case an extra length of third rail from Hurst Green would seem to be the logical option.

For all the currently unelectrified lines, I would hope that a short extension of third rail 'around the corner' (so to speak) was permitted to allow trains to get up to speed on the juice, and to be held prior to the junction on an electrified section so they can get charging. Wouldn't need to be any longer than a couple of hundred meters though.

The 48 miles for a round trip between Hurst Green and Uckfield is within the quoted ranges of international BEMUs. FLIRT Akku claimes 150km/93miles. The new Irish Rail 90,000 Class expect 80km/50 mile ranges even at end of life.

Operationally - it doesn't.

The real difference is that a compromise has to be made because it joins two pre-existing electrified networks, which means that a compromise is necessary to allow the service to run. For Uckfield or Romney Marsh, there would be a specific decision to embed that inflexibility in the long term where there is an option to avoid that.

These services already operate with a microfleet of 17x 171s, of course. Which was a specific decision to embed the inflexibility of needing diesels to operate those services. At least if your BEMUs were the same platform as the EMUs there'd be commonality of maintenance arrangements and so forth.

You could even choose to buy an All-BEMU fleet sufficient to operate all longer-distance services so that diagramming and allocations could be completely flexible. Which would also mean that if the power was disrupted for any reason, services could keep moving.

 

[tbtc]

This is how conspiracies start, people start to believe there's some "agenda" against their favourite option just because governments haven't agreed with things that electrical enthusiasts assume should be "simple"/"obvious"

To give context, whilst we argue about the merits of putting Third Rail on lines with hourly trains (Uckfield etc), there are plenty of lines elsewhere in the country seeing significantly more which remain unwired - that doesn't mean there's a ban on overhead electrification, just that not everything we view as a "slam dunk" or "shovel ready" happens

For example, there are plenty of services that see a DMU running so far under the wires, just like Uckfield services currently have pure DMUs running on the Third Rail north of Hurst Green, yet nobody claims there's a conspiracy about why e.g. Buxton or Windermere remain unwired

Reading - Redhill sees DMUs running on Third Trail track at both ends, sure, rather similar to e.g. Lime Street - Warrington Central - Oxford Road services or Leeds - Harrogate - York trains which depart and arrive under the wires but the middle sections haven't been done

In the long term, Basingstoke to Exeter might have a case, but there's a lot of much bigger stations that remain unelectrified (Temple Meads, Oxford, Moor Street/ Snow Hill, Nottingham, Derby, Sheffield, Dundee, Aberdeen...) - the hourly service west of Salisbury doesn't seem like a national priority when you consider the shopping list the government has

If The Powers That Be had insisted on even East London Line infills being overhead electrification then I could understand the arguments being made here, but I can't think of an example of any lines where we've used AC rather than DC without there being an obvious reason (e.g. Reading to Basingstoke would mean the overhead GWML meeting the Third Rail services out of Waterloo, so any option would have been imperfect - same with Thameslink)

 

[zwk500]

yet nobody claims there's a conspiracy about why ... Windermere remain unwired

Perhaps a bad example, as there is claim and counter-claim about whether or not the National Park/Local Residents did actually claim eyesore to prevent the line being wired.

 

[GRALISTAIR]

I agree with short infill sections that are no-brainer common sense. However, there should be no more lengthy 3rd rail installations. Basingstoke to Salisbury/Exeter, should be an absolute no-no as far as I am concerned.

In the long term, Basingstoke to Exeter might have a case,-----

For 25kV AC OHLE yes.

 

[Harpo]

BEMUs would probably constitute a sub-fleet but if it leads to elimination of niche ICE & liquid fuel facilities, the addition of traction batteries to EMU maintenance is surely a much better fit?

 

[Magdalia]

That may be, but the issue is also one of principle - replacing the current DMU fleets with restricted use sub-fleets is a seriously sub-optimal way of resourcing these lines. The objective should be to have a common fleet

How does it differ from Southern having eight 377/7s for three West London Line diagrams?

These services already operate with a microfleet of 17x 171s, of course. Which was a specific decision to embed the inflexibility of needing diesels to operate those services. At least if your BEMUs were the same platform as the EMUs there'd be commonality of maintenance arrangements and so forth.

The microfleet argument is a red herring, as the existing dual voltage EMUs demonstrate.

When the Southern class 377 fleet comes up for renewal it will be easy to have a fleet consisting mostly of straight EMUs with a subfleet with batteries, that can also operate just like a straight EMU. These would be used on all of Marshlink, Uckfield and North Downs, with the flexibility of also being capable of performing as a straight EMU on other services. It would even be possible to go back to having Uckfield/East Grinstead trains splitting at Oxted.

 

[Halifaxlad]

If it was lifted in it's entirety we would end up with suggestions such as using 3rd on the Harrogate line or worse the Calder Valley Line.

What we need is less train types not more!

 

[nw1]

There is zero case for any of these, whatever the financial circumstances. All of them will be electrified much more cheaply and much more safely with electric/battery bimode trains.

I would say there is a case, but presumably not enough money to do so at the moment. They're all in the "Southern" and within third-rail land. It thus would make perfect place to third-rail them if the economic situation was better and stock was available.

I'd have said the ideal time to electrify all these routes was during the stock renewal around 2004, but the opportunity was not taken. The economic situation was IIRC better, and they could have just ordered more 377s, 450s, etc.

 

[35B]

The microfleet argument is a red herring, as the existing dual voltage EMUs demonstrate.

When the Southern class 377 fleet comes up for renewal it will be easy to have a fleet consisting mostly of straight EMUs with a subfleet with batteries, that can also operate just like a straight EMU. These would be used on all of Marshlink, Uckfield and North Downs, with the flexibility of also being capable of performing as a straight EMU on other services. It would even be possible to go back to having Uckfield/East Grinstead trains splitting at Oxted.

And that is precisely why I am so hostile to the unforced error of embedding use of a microfleet. You can achieve precisely the same outcome by electrifying the lines, and enabling a common fleet (currently cl. 377) to operate flexibly across all of those - and without requiring dedicated maintenance and diagramming to provide the service.

 

[Tetragon213]

Imo, the regulations surrounding 3rd rail warrant some easing. I do think there is a business case for electrifying Worting Jn-Salisbury-Exeter with 3rd rail, as well as doing Reading-Basingstoke or even Liverpool-Wigan-Manchester.

As it stands, the regulations seem a bit too stifling, compared to the benefits of electrifying with the cheaper 3rd rail option. I'd wager the deaths caused on the roads by people being priced out of rail or unable to make journeys due to itineraries not matching up, far outweighs the risks associated with trespassers frying themselves. On that note, as harsh as it sounds, I struggle to have sympathy for idiots who knowingly break through a fence panel, ignore the "Do not trespass on the Railway Penalty £1000" signs, and promptly turn themselves into a 1000-ohm resistor.

 

[yorksrob]

I agree with short infill sections that are no-brainer common sense. However, there should be no more lengthy 3rd rail installations. Basingstoke to Salisbury/Exeter, should be an absolute no-no as far as I am concerned.


For 25kV AC OHLE yes.

I sort of agree. I could see an argument for third rail as far as Salisbury, so that stoppers could be more easily integrated into the rolling stock pool. However a long distance stretch, such as onwards to Exeter should be OLE.

 

[Autspectorder]

Here is a slightly crazy idea. Electrify with 750V overhead wire and put pantographs on some of the third-rail units.

 

[Bletchleyite]

Here is a slightly crazy idea. Electrify with 750V overhead wire and put pantographs on some of the third-rail units.

Is there any benefit of doing that? It is done for trams, but that probably has more to do with safety relating to overhead lines in towns rather than on the line of route, plus not needing a big heavy transformer on a lightweight vehicle.

If you're putting wires up on heavy rail surely it might as well just be 25kV? Pretty much all third rail stock in current operation is capable of having a pantograph and transformer fitted aside from the Merseyrail battery fitted units as the batteries go where the transformer would.

 

[Autspectorder]

Is there any benefit of doing that? It is done for trams, but that probably has more to do with safety relating to overhead lines in towns rather than on the line of route, plus not needing a big heavy transformer on a lightweight vehicle.

You avoid the safety issues that comes with third rail electrification.

 

[35B]

Is there any benefit of doing that? It is done for trams, but that probably has more to do with safety relating to overhead lines in towns rather than on the line of route, plus not needing a big heavy transformer on a lightweight vehicle.

If you're putting wires up on heavy rail surely it might as well just be 25kV? Pretty much all third rail stock in current operation is capable of having a pantograph and transformer fitted aside from the Merseyrail battery fitted units as the batteries go where the transformer would.

Absolutely - especially as adopting 25kV gives other significant savings.

== Doublepost prevention - post automatically merged: 6 Mar 2026 ==

You avoid the safety issues that comes with third rail electrification.

While adding some others, making installation more expensive and forfeiting the other gains from adopting 25kV. There are very few places where this is really relevant.

 

[Magdalia]

You can achieve precisely the same outcome by electrifying the lines

It isn't precisely the same outcome because electrification costs more than equipping a subfleet of EMUs with batteries. Furthermore it is an upfront capital project with financing costs and opportunity costs because those funds can't be used elsewhere. It is only precisely the same outcome with a bottomless pit of free money, and the railway doesn't have that.

a common fleet (currently cl. 377) to operate flexibly across all of those

The class 377s fleet doesn't operate flexibly across all lines. Dual voltage units have to be provided for trains that need OHL. Battery equipped units would actually be better than dual voltage units because there would be more of them, and they could be used on the West London trains too, dispensing with the need for dual voltage units.

 

[Tetragon213]

Here is a slightly crazy idea. Electrify with 750V overhead wire and put pantographs on some of the third-rail units.

Not a bad idea, as that's pretty much what all the trams run on. It would make re-engineering slightly easier for the new units, at least.

I sort of agree. I could see an argument for third rail as far as Salisbury, so that stoppers could be more easily integrated into the rolling stock pool. However a long distance stretch, such as onwards to Exeter should be OLE.

West of Salisbury is very stop-start, so you'd never really get the benefit of the higher speed available with OLE. Not to mention Salisbury is NIMBY central, full of narrow-minded, selfish busybodies with nothing better to do than complain about change and launch legal challenges against the winds of time. Not to mention they seem to always have money to spend on legal challenges, but never enough to pay their own rounds. You'd struggle to get OLE up in any reasonable time frame.

 

[zwk500]

Imo, the regulations surrounding 3rd rail warrant some easing. I do think there is a business case for electrifying Worting Jn-Salisbury-Exeter with 3rd rail, as well as doing Reading-Basingstoke or even Liverpool-Wigan-Manchester.

Reading-Basingstoke should be OLE. The interaction at Reading is considerably more complex than sending the wire into P5 at the south end. Would also be better suited for 93 or 99-hauled freight.

Worting-Salisibury-Romsey-Eastleigh/Redbridge for 3rd rail I could see, but beyond to Exeter is not for third rail.

You avoid the safety issues that comes with third rail electrification.

If you're putting up DC overheads, then it'd be at 3KV, which is the 2nd most popular electrification system globally for heavy rail, or 1.5KV, which is also a very popular system and used often by high-density metro networks.

 

[Snow1964]

Imo, the regulations surrounding 3rd rail warrant some easing. I do think there is a business case for electrifying Worting Jn-Salisbury-Exeter with 3rd rail.

I don't but there is a strong case for extending third rail from Worting Junction to Andover (and adding a turn back at Andover), extending the trains that currently terminate at Basingstoke.

Simply because of the number of homes that have been built since mid 1960s (when Bournemouth electrification was done) at west Basingstoke and Andover area (and which might get the proposed new town at Laverstoke).

Beyond Andover would look at 25kv, unless the 25kv electric spine (Reading - Basingstoke - Southampton docks via Winchester and Laverstoke spur is revived)

 

[Tetragon213]

I don't but there is a strong case for extending third rail from Worting Junction to Andover (and adding a turn back at Andover), extending the trains that currently terminate at Basingstoke.

Simply because of the number of homes that have been built since mid 1960s (when Bournemouth electrification was done) at west Basingstoke and Andover area (and which might get the proposed new town at Laverstoke).

Beyond Andover would look at 25kv, unless the 25kv electric spine (Reading - Basingstoke - Southampton docks via Winchester and Laverstoke spur is revived)

Oh yeah, Andover has grown massively. However, if you're going to extend to Andover, you might as well go all the way to Salisbury. Helpfully, there is already a crossover siding at Andover, and space for reinstatement of the passing lines for a Dewsbury-esque layout if needed.

 

[35B]

Oh yeah, Andover has grown massively. However, if you're going to extend to Andover, you might as well go all the way to Salisbury. Helpfully, there is already a crossover siding at Andover, and space for reinstatement of the passing lines for a Dewsbury-esque layout if needed.

Why the obsession with 3rd rail to Salisbury, given that transition there would still risk the NIMBYs? I can see good logic in the Andover idea, avoiding transition effects at the major junction of Basingstoke/Worting, and accepting the need for 25kV on major lengths.

However, I still come back to the presumption and the lack of need for DC 3rd rail - what’s being suggested here is a commercial need, not a hard physical one.

 

[stuu]

Here is a slightly crazy idea. Electrify with 750V overhead wire and put pantographs on some of the third-rail units.

I would suggest looking at the size of conductors which 1.5kV DC needs to move a train and then working out how big a 750V conductor would need to be. Effectively it would need to be an aerial conductor rail

 

[GRALISTAIR]

If you're putting wires up on heavy rail surely it might as well just be 25kV?

Absolutely agree.

 

[MarkyT]

Eastleigh ‘up freight loop’ (as it was originally described), but also used by up stopping passenger services, is relatively minor in length but shows a new third track added alongside the existing lines would be powered by third rail.

It's been policy for many years to treat lines intended mainly for freight as passenger lines from a signalling POV in new schemes, and there have been several smaller projects to upgrade individual loops using the existing signalling systems.

Historically, there were certain cost-saving shortcuts the railway could employ on goods lines, including avoiding overlaps and Facing Point Locks. In early power signalling, there were slightly less complex variants of common point machines available without the internal FPL mechanism, while today NR only buys machines with an FPL or equivalent (except for a few specialised motorised non-passenger yard points that can be trailed through in the opposite position without damage).

That these goods lines and loops weren't fully signalled to passenger standards never stopped them being used for diversions, but it meant additional resources and time consuming measures were necessary, such as having staff on site to manually clip and padlock the points for facing passenger movements. Adopting passenger signalling standards by default (at very little additional cost in practice) protects bigger and faster modern freight trains as well the other traffic it must interact with en route. When a passenger diversion is necessary, a reroute to the freight loop can be achieved any time the line is clear, with no need to organise trackside staff or caution drivers (assuming they have the route knowledge!).

I’d always assumed any sensible three or four tracking of existing routes would be allowed third rail as a matter of course.

Yes, but for very extensive work, I'd also expect additional safety measures in the final power system for all tracks in the corridor. That could include removal of level crossings, fencing improvements, more sophisticated isolation for maintenance, emergency, etc. A fleet with all emus equipped with a small battery that could power through larger conductor rail gaps could also allow much simplification of the 3rd rail infrastructure around junctions, and conductor might also be omitted from certain plain track areas where justified for safety reasons, or only energised when a train is present or signalled.

 

[zwk500]

Absolutely agree.

I can see an argument for the pragmatic side of keeping the DC area still on DC. The French certainly felt it was worth exploring for their 9KV trial.

 

[Autspectorder]

I would suggest looking at the size of conductors which 1.5kV DC needs to move a train and then working out how big a 750V conductor would need to be. Effectively it would need to be an aerial conductor rail

Here is an example of how 750V DC electrification can look like.

 

[zwk500]

Here is an example of how 750V DC electrification can look like.

If you are going to the effort of installing OLE, you would up the voltage. I can see the logic in staying DC and going to 3KV DC rather than the full-fat 25KV AC, but I cannot see any justification for the cost of installing overhead lines at the same voltage as the current system.

(Although personally, installing OLE on the southern region would only be worth it if you took the opportunity to harmonise on the 25KV AC standard).