Why no longer Third Rail Electrification?

[Roast Veg]

Set against this is that the AC trains are a bit more expensive - and of course the much-discussed costs of raising bridges etc.

Out of curiosity, is that more expensive to run or to build, and if it's to run then is it only on AC sections? I ask because we are now well into an era in which all EMUs are being bought with full capacity to be converted to AC.

 

[edwin_m]

Out of curiosity, is that more expensive to run or to build, and if it's to run then is it only on AC sections? I ask because we are now well into an era in which all EMUs are being bought with full capacity to be converted to AC.

I think this refers to the transformer and pantograph that would be provided on AC-capable units. Many of these don't provide the equipment itself, just the mountings and cabling so it can be added later if required. In that case the extra cost at build time is likely to be minimal compared to the cost of the unit as a whole.

If the AC equipment itself isn't fitted, then a weight is (usually, maybe not always) fitted instead so the weight distribution isn't affected. As I posted above, the extra cost of hauling either the equipment or the weight around must be around a percent or two on energy costs, and energy costs are only a part of running costs. This would however be a cost when running on DC as well as AC.

 

[AM9]

I think this refers to the transformer and pantograph that would be provided on AC-capable units. Many of these don't provide the equipment itself, just the mountings and cabling so it can be added later if required. In that case the extra cost at build time is likely to be minimal compared to the cost of the unit as a whole.

If the AC equipment itself isn't fitted, then a weight is (usually, maybe not always) fitted instead so the weight distribution isn't affected. As I posted above, the extra cost of hauling either the equipment or the weight around must be around a percent or two on energy costs, and energy costs are only a part of running costs. This would however be a cost when running on DC as well as AC.

The difference in running costs of an ac/DC EMU vs. a DC only EMU, (consider a 350 vs. 450), would be a fraction of the cost of the difference in costs between ac and DC running. I would imagine in the order of 10 times more expensive for DC running even if it wasn't carrying the weight of the hardware necessary for ac operation.

 

[A0wen]

I think this thread is getting distracted between DC and AC - whereas the OPs question was why no more 3rd rail.

You can of course have DC on overhead....

The reason why no more on 3rd rail is probably a mixture of factors, for longer stretches of line the infrastructure needed for AC make it more economic to go that route, which conspires against 3rd rail.

There are then the obvious health and safety concerns around having a high voltage, high current power source laying about on the floor with no protection. And whilst I accept members of the public *shouldn't* be on the rails, the fact remains some do end up there being electrocuted. Then again there have been no shortage of cases of rail workers being electrocuted by the 3rd rail and they're safety trained to be aware of it. And as others have pointed out, it does tend to frazzle certain types of wildlife which stray across the tracks - badgers and foxes seem to be the most common.

In terms of reliability, despite the claims of some posters, I don't believe that OHL is inherently less reliable than 3rd rail - 3rd rail is as susceptible to problems such as damage to the rail, yet it probably isn't reported in that way.

 

[AM9]

I think this thread is getting distracted between DC and AC - whereas the OPs question was why no more 3rd rail.

You can of course have DC on overhead....

The reason why no more on 3rd rail is probably a mixture of factors, for longer stretches of line the infrastructure needed for AC make it more economic to go that route, which conspires against 3rd rail.

There are then the obvious health and safety concerns around having a high voltage, high current power source laying about on the floor with no protection. And whilst I accept members of the public *shouldn't* be on the rails, the fact remains some do end up there being electrocuted. Then again there have been no shortage of cases of rail workers being electrocuted by the 3rd rail and they're safety trained to be aware of it. And as others have pointed out, it does tend to frazzle certain types of wildlife which stray across the tracks - badgers and foxes seem to be the most common.

In terms of reliability, despite the claims of some posters, I don't believe that OHL is inherently less reliable than 3rd rail - 3rd rail is as susceptible to problems such as damage to the rail, yet it probably isn't reported in that way.

I agree with all that you've said above except that the decision about more third rail electrification can only be considered against the case for that vs. 25kV OLE. For heavy rail, there is no case for anything other than 25kV ac on OLE since the removal of 6.25kV in the late '70s and the last installation of 1500VDC in the early '50s. The majority of all new electrification schemes (certainly in the 50Hz world) are at 25kV 50Hz ac even in countries with extensive legacy 1500/3000VDC systems so consequently, suppliers have developed their products with that demand in mind.
Even when the EU influence on selection of systems no longer impacts directly on the UK, it is extremely unlikely that anything else would even be considered for anything other than closed loop light rail projects.

 

[janahan]

.......
Even when the EU influence on selection of systems no longer impacts directly on the UK, it is extremely unlikely that anything else would even be considered for anything other than closed loop light rail projects.

I think the UK decided on 25kv 50hz well before we became a part of the EEC.

 

[najaB]

I think the UK decided on 25kv 50hz well before we became a part of the EEC.

Indeed. I believe it was chosen in the mid 1950s. Certainly the WCML electrification of the late 1960s predates joining the EEC.

 

[AM9]

I think the UK decided on 25kv 50hz well before we became a part of the EEC.

Where did I say that the decision to adopt the 25kV ac OLE system was anything to do with the EU? The decision was made following successful experiments and implementation by SNCF.
The fact is that the EU TSI has an influence on the way that we design, construct and operate our railway network. Without going OT, the wholesale removal of any obligation to adhere to the TSI rules by virtue of leaving the EU is in my view very unlikely to happen.

 

[Tio Terry]

Where did I say that the decision to adopt the 25kV ac OLE system was anything to do with the EU? The decision was made following successful experiments and implementation by SNCF.
The fact is that the EU TSI has an influence on the way that we design, construct and operate our railway network. Without going OT, the wholesale removal of any obligation to adhere to the TSI rules by virtue of leaving the EU is in my view very unlikely to happen.

I would agree with you. Whilst the UK may well leave the EU the benchmark standard that the EU sets is very likely to remain the UK standard if only for Interoperability reasons. It would be a very brave member of the DfT/ORR who decided that what was right and safe for the EU was not appropriate for the UK! Being within the EU meant that we could have an influence on the ERA and it's decisions, following Brexit all we can do is note their decisions, we have no influence, no input, anymore.

 

[Domh245]

I would agree with you. Whilst the UK may well leave the EU the benchmark standard that the EU sets is very likely to remain the UK standard if only for Interoperability reasons. It would be a very brave member of the DfT/ORR who decided that what was right and safe for the EU was not appropriate for the UK! Being within the EU meant that we could have an influence on the ERA and it's decisions, following Brexit all we can do is note their decisions, we have no influence, no input, anymore.

I think that what is more likely to happen is that we'll adopt whatever the current EU practice is and then once we've sorted out the massive stack of other things that need sorting out, we can then adjust our rules as necessary, because let's be honest - railway standards probably aren't at the top of the pile for things that need sorting out in the wake of Brexit. It'd be particularly daft to tie ourselves to future EU regulation if we don't plan on any interoperability given that some of the UK specific exclusions would no longer need to be included, but then again we apparently have ignored these anyway (hence the bridge clearance issues with ongoing electrification schemes)

 

[pacenotes]

For 3rd rail you need a sub station every 6km whereas for overhead wires it is 60km. So that would be a huge saving in installation costs.

 

[Elecman]

For 3rd rail you need a sub station every 6km whereas for overhead wires it is 60km. So that would be a huge saving in installation costs.

And an 11kv feeder cable from the traction supply feeding station along the track to every substation to provide the power to the rectifiers.

 

[SpacePhoenix]

If the electric spine doesn't happen, would 3rd rail from Basingstoke, through the lines that can connect up with the Reading-Waterloo route be allowed to allow 3rd rail from Basingstoke-Waterloo via Reading?

 

[paul1609]

Approximately 8 + DC Containers (TPHs).

Crowthorne - Blackwater - Shalford - Albury - Gomshall - Westcott - Betchworth - Reigate

Approx 3 miles apart.

They might be able to do one at Farnborough North as there's a substation there which feeds the mainline (conveniently), so just increase it in size or power. So the above locations between Wokingham & Ash might need rejigging a bit.

Ive often wondered if it would be possible to use power from the Dorking to Horsham line to stretch the Reigate Electrification as far as Dorking Deepdene or even perhaps Dorking West utilising one of the composite conductor rails. I reckon there would be considerable demand for a faster Dorking to London via Croydon service and this would seem to be possible by extending the Reigate terminating services with maybe a one train in section limitations. I presume the reigate electrification is just an extension off the BML and doesn't have its own sub station?

 

[edwin_m]

I think that what is more likely to happen is that we'll adopt whatever the current EU practice is and then once we've sorted out the massive stack of other things that need sorting out, we can then adjust our rules as necessary, because let's be honest - railway standards probably aren't at the top of the pile for things that need sorting out in the wake of Brexit. It'd be particularly daft to tie ourselves to future EU regulation if we don't plan on any interoperability given that some of the UK specific exclusions would no longer need to be included, but then again we apparently have ignored these anyway (hence the bridge clearance issues with ongoing electrification schemes)

Countries such as China and South Korea, which have no obligation to follow EU rules, have adopted essentially the same set of standards for their own high speed operations. It will almost always be cheaper and lower risk to adopt something that someone else has proved is reliable in service and for which kit is available off the shelf.

 

[D365]

... but then again we apparently have ignored these anyway (hence the bridge clearance issues with ongoing electrification schemes)

See, we're creating all our own problems

If the electric spine doesn't happen, would 3rd rail from Basingstoke, through the lines that can connect up with the Reading-Waterloo route be allowed to allow 3rd rail from Basingstoke-Waterloo via Reading?

Why would the Basingstoke-Reading trains be connected to Reading-Waterloo? They're two completely different services.

 

[matacaster]

Is the lack of 3rd rail expansion due to the environmental lobby?

Are ANY badgers safe with 3rd rail electrfication (especially if its not been pet sic (P.A.T.) tested?

 

[najaB]

Is the lack of 3rd rail expansion due to the environmental lobby?

Not particularly, no.

 

[AM9]

Is the lack of 3rd rail expansion due to the environmental lobby?

Are ANY badgers safe with 3rd rail electrfication (especially if its not been pet sic (P.A.T.) tested?

The decisions to limit future 3rd rail expansion to virtually nothing has been influenced by several negative issues that it is responsible for:

it is much less safe than OLE for staff, passengers as well as trespassers and wildlife
it is much more wasteful on energy than HV OLE for most mainline applications
it requires complex and expensive feeder equipment in greater quantities per track kilometre
it requires that performance of modern rolling stock is limited artificially to keep the electrical load within the system's capabilities
it has climatic vulnerabilities that are more difficult/impossible to mitigate than for OLE
as time goes on, it is becoming more non-standard, resulting in equipment, materials and human resource shortages​

In summary, the above negative incentives to 3rd rail expansion can be attributed to environmental, safety, maintainability and economic reasons. The combined effect is driving a political will that likely prevents any more 3rd rail from being authorised.

 

[SpacePhoenix]

Why would the Basingstoke-Reading trains be connected to Reading-Waterloo? They're two completely different services.

As a diversion route during times of disruption and/or engineering works east of Basingstoke

 

[yorksrob]

The decisions to limit future 3rd rail expansion to virtually nothing has been influenced by several negative issues that it is responsible for:

it is much less safe than OLE for staff, passengers as well as trespassers and wildlife
it is much more wasteful on energy than HV OLE for most mainline applications
it requires complex and expensive feeder equipment in greater quantities per track kilometre
it requires that performance of modern rolling stock is limited artificially to keep the electrical load within the system's capabilities
it has climatic vulnerabilities that are more difficult/impossible to mitigate than for OLE
as time goes on, it is becoming more non-standard, resulting in equipment, materials and human resource shortages​

In summary, the above negative incentives to 3rd rail expansion can be attributed to environmental, safety, maintainability and economic reasons. The combined effect is driving a political will that likely prevents any more 3rd rail from being authorised.

I don't believe for one moment that the third rail is less safe than OLE for passengers, primarily because there is less danger of arcing.

I don't believe that it is any more vulnerable to climactic conditions than OLE because we seem to have far more instances of disruption involving the knitting than otherwise.

I also don't see how the equipment can be considered non standard when the majority of the Southern region is electrified with it.

However, even if all of the shortcomings were true, that's not really an excuse for continuing diesel islands in areas where third rail until S the only practical form of electrification (unless perhaps they have success with the battery train).

I

 

[SpacePhoenix]

It can be more vulnerable to debris causing a dead short (eg a few months back at iirc Gatwick

 

[edwin_m]

I don't believe for one moment that the third rail is less safe than OLE for passengers, primarily because there is less danger of arcing.

Ironically there is more danger of arcing with the lower voltage system, because the current in the event of a fault is not much more than if a couple of trains happen to be accelerating at the same time. So a partial short such as a drinks can lodged between the third rail and the running rail may not trip out the supply. This could and has caused arcing and fire over a significant period of time until the supply is shut off manually. 25kV will almost always cut out within a fraction of a second of any fault.

Passengers are also exposed to danger from the third rail if they fall from a platform or deliberately descend to retrieve a phone etc. It's much harder to get into a position where OLE is similarly hazardous.

 

[4973]

I don't believe for one moment that the third rail is less safe than OLE for passengers, primarily because there is less danger of arcing.

What's the likelihood of arcing compared to the dangers of someone falling off the platform ? Yes I know the 3rd rail is put on the side away from the platform most of the time, but that's not always possible.

I don't believe that it is any more vulnerable to climactic conditions than OLE because we seem to have far more instances of disruption involving the knitting than otherwise.

I have to wonder if you have ever travelled in 3rd rail territory during a really heavy snowfall. However if the Southern top-contact system were converted to side-contact (A la Manchester - Bury) things might be different, but that conversion would be another (and major cost and disruption).

I also don't see how the equipment can be considered non standard when the majority of the Southern region is electrified with it.

The size of the Southern system is miniscule compared with the market for 25Kv OLE equipment and is market size that determines the cost of individual items of equipment.




Talk about people who don't WANT to see.

 

[DarloRich]

Is the lack of 3rd rail expansion due to the environmental lobby?

Are ANY badgers safe with 3rd rail electrfication (especially if its not been pet sic (P.A.T.) tested?

what on earth are you talking about? Badgers?

 

[yorksrob]

Ironically there is more danger of arcing with the lower voltage system, because the current in the event of a fault is not much more than if a couple of trains happen to be accelerating at the same time. So a partial short such as a drinks can lodged between the third rail and the running rail may not trip out the supply. This could and has caused arcing and fire over a significant period of time until the supply is shut off manually. 25kV will almost always cut out within a fraction of a second of any fault.

Passengers are also exposed to danger from the third rail if they fall from a platform or deliberately descend to retrieve a phone etc. It's much harder to get into a position where OLE is similarly hazardous.

In terms of arcing, it's more the distance over which arcing can take place, rather than the frequency, which is presumably why there are strictures about what height you can safely get to on the edge of a platform (without going anywhere near the cable) with OLE, whereas there is no such risk with third rail.

In terms of platforms, there is a long standing convention that the third rail is always laid on the opposite side to the platform face, which negates the hazard of people falling on to it.

 

[yorksrob]

What's the likelihood of arcing compared to the dangers of someone falling off the platform ? Yes I know the 3rd rail is put on the side away from the platform most of the time, but that's not always possible.



I have to wonder if you have ever travelled in 3rd rail territory during a really heavy snowfall. However if the Southern top-contact system were converted to side-contact (A la Manchester - Bury) things might be different, but that conversion would be another (and major cost and disruption).



The size of the Southern system is miniscule compared with the market for 25Kv OLE equipment and is market size that determines the cost of individual items of equipment.




Talk about people who don't WANT to see.

The occasions when the third rail would need to be laid on the platform side are extremely rare and can usually be designed away. Double sided platforms are very rare and it is highly likely that one side can be taken out of use, just as Pointwork and crossovers are now more likely to be installed away from the platform area. These are examples of sensible measures that can be used to mitigate risk, rather than hysterically banning third rail.

I have travelled in third rail territory in snow, and the fact is that is most likely to happen on those rare occasions when the whole part of the country has ground to a halt, rather than every so often when it gets a bit windy. I have also been on a very crowded diesel train up the MML due to the train being full of East Coast passengers whose AC electric trains had been disrupted by snow.

As for the Southern Region being "tiny" it is quite large enough to enable a decent supply chain of components and expertise.

I see lots of things, including unnecessary hysteria.

 

[SpacePhoenix]

As for the Southern Region being "tiny" it is quite large enough to enable a decent supply chain of components and expertise.

There's also MerseyRail that uses 3rd rail. Apart from MerseyRail, SWTs, GTR and SouthEastern I can't think of any other TOC that uses 3rd rail

 

[yorksrob]

There's also MerseyRail that uses 3rd rail. Apart from MerseyRail, SWTs, GTR and SouthEastern I can't think of any other TOC that uses 3rd rail

Indeed, however these do make up a reasonable amount of mileage and expertise between them.

I can't remember whether the"clockwork orange" in Glasgow uses third or fourth rail.

 

[A0wen]

There's also MerseyRail that uses 3rd rail. Apart from MerseyRail, SWTs, GTR and SouthEastern I can't think of any other TOC that uses 3rd rail

Mersey Rail's is a mix of legacy and the clearances in the tunnels.

Their new rolling stock will almost certainly be dual-voltage which will then raise the question at some point of converting the above surface lines to OHL with changeovers at certain points for the tunnels - basically the same situation as the GN Moorgate services.