RSSB looking at possible extension of 3rd rail electrification

[Bald Rick]

Which is why modern high performance third rails are mostly made of aluminium?

Good to know - I honestly did not know that - thanks

Composite third rail was used for a few renewals on the Southern around 15 years ago, but pretty quickly dropped. I don’t know why. I think LU still uses composite stuff in tunnels. I wonder if it something to do with the temperature / weather effect on it.

 

[Philip Phlopp]

Composite third rail was used for a few renewals on the Southern around 15 years ago, but pretty quickly dropped. I don’t know why. I think LU still uses composite stuff in tunnels. I wonder if it something to do with the temperature / weather effect on it.

Yeah, temp/weather rings a bell, wasn't there some issue about ice formation ?

 

[corfield]

I'm sure there are a number of us here whose children have worked through 200 minor injuries over time (as in need to get the bandage box out), and in no way consider that to equal a child fatality.

That’s probably because you don’t know what a Minor Injury is, it is not the “bandage box”, from the NHS (note the last one):

• Cuts & bruises
• Sprains
• Small burns
• Foreign bodies
• Head injuries where the patient has not lost consciousness
• Any injury which you can’t deal with yourself at home

 

[GRALISTAIR]

The coefficient of linear thermal expansion of (ordinary carbon) steel is approximately half that of aluminium Not that that would matter much as not a running rail.

 

[edwin_m]

The coefficient of linear thermal expansion of (ordinary carbon) steel is approximately half that of aluminium Not that that would matter much as not a running rail.

It doesn't appear to be very well fixed down on the "pots", so I assume it is free to expand with gaps at suitable intervals connected electrically by cables.

I've an idea the Southampton-Portsmouth electrification used composite conductor rail, "composite" in this case meaning a steel running surface as the aluminum wasn't suitable. Not sure if it wore too quickly or something to do with it forming a tough and insulating oxide layer after a short time exposed to air. The different coefficients of expansion might cause problems with it bending like a bimetallic strip, or the two becoming separated after a time.

 

[Dunfanaghy Rd]

The composite rail didn't last all that long. Not in comparison to the juice rail on the Worplesdon length when I started in the 70s, which was the original from 1937.
However, some silver-tongued salesman got an export order. Southampton Eastern Docks, can't remember the date, but I had the neg scanned in 2009.

Pat

 

[Romsey]

Which is why modern high performance third rails are mostly made of aluminium?

I think aluminium 3rd rails are still at the experimental stage for NWR. There was a length installed between Botley and Fareham in the early 1990's, but a few years later the steel contact strip became detached from the main aluminium rail. It immobilised the unit which was passing for some hours and the whole length of 3rd rail needed to be replaced. I suspect there is an element of "coming second" to allow others to make the mistakes...
Conductor rails are rolled to a special cross section and use a lower electrical resistance grade of steel to running rails.

 

[Bald Rick]

The composite rail didn't last all that long. Not in comparison to the juice rail on the Worplesdon length when I started in the 70s, which was the original from 1937.
However, some silver-tongued salesman got an export order. Southampton Eastern Docks, can't remember the date, but I had the neg scanned in 2009.
View attachment 80627View attachment 80628
Pat

I pulled out con rail on the Hounslow loop in 2004 that dated from the original electrification in 1916.

 

[GRALISTAIR]

I think aluminium 3rd rails are still at the experimental stage for NWR. There was a length installed between Botley and Fareham in the early 1990's, but a few years later the steel contact strip became detached from the main aluminium rail. It immobilised the unit which was passing for some hours and the whole length of 3rd rail needed to be replaced. I suspect there is an element of "coming second" to allow others to make the mistakes...
Conductor rails are rolled to a special cross section and use a lower electrical resistance grade of steel to running rails.

That was more my understanding too and using a special lower resistance grade of steel makes sense too.

 

[Western Sunset]

3rd rail to Uckfield seems to be a "no-brainer" to me. Why can't we just get on and do stuff without never-ending (and expensive) consultations?

 

[Bald Rick]

3rd rail to Uckfield seems to be a "no-brainer" to me. Why can't we just get on and do stuff without never-ending (and expensive) consultations?

Leaving aside the principles of new third rail installations that have been well explained repeatedly upthread... the Uckfield line will need a substantial sub-station to supply the power (.regardless of type of electrification. How would you feel if this was built next door to your house? That’s why consultation is required.

 

[Western Sunset]

Actually, where I grew up in Derby, there was a substation just down the lane by our cottage, for the trolleybuses.

 

[Bald Rick]

Actually, where I grew up in Derby, there was a substation just down the lane by our cottage, for the trolleybuses.

A railway feeder substation is a rather different proposition!

 

[yorksrob]

It's a shame that the mid-1980s Network South East original plan to extend 3rd rail to Weymouth, substituting 4-CIG stock, and transferring the REP+TC arrangement to an electrified service through to Salisbury (or 4-CIG for what terminated there), with the 33s taking one set on to Exeter, was never seen through. Apparently it was a quite close decision.

That sounds as though it would have been sn excellent outcome for passenger comfort.

Leaving aside the principles of new third rail installations that have been well explained repeatedly upthread... the Uckfield line will need a substantial sub-station to supply the power (.regardless of type of electrification. How would you feel if this was built next door to your house? That’s why consultation is required.

I wouldn't object to a "cathedral" type sub station, of the type found in the south eastern suburbs. Very impressive to look at. I wouldn't fancy one of the Southern railway 1930's ones as found on the Sussex coast as they strike me as a bit brutalist. The Kent electrification scheme ones from the 50's and 60's are a bit bland, albeit comfortingly familiar in that I hail from that neck of the woods, but probably not to everyones taste.

Perhaps we should settle for the chalet style as used for the Hastings line in the 1980's. People would hardly notice it was there !

 

[Bald Rick]

That sounds as though it would have been sn excellent outcome for passenger comfort.


I wouldn't object to a "cathedral" type sub station, of the type found in the south eastern suburbs. Very impressive to look at. I wouldn't fancy one of the Southern railway 1930's ones as found on the Sussex coast as they strike me as a bit brutalist. The Kent electrification scheme ones from the 50's and 60's are a bit bland, albeit comfortingly familiar in that I hail from that neck of the woods, but probably not to everyones taste.

Perhaps we should settle for the chalet style as used for the Hastings line in the 1980's. People would hardly notice it was there !

You could expect half a dozen grey boxes! And an 8ft palisade fence.

 

[yorksrob]

You could expect half a dozen grey boxes! And an 8ft palisade fence.

Oh dear, It's clearly not just the moquette design that's gone down hill in the last twenty years !

 

[Domh245]

I think the point was more that the Railway can't just go around building things without carrying out due process first, rather than any preference on substation architecture!

 

[corfield]

It's a shame that the mid-1980s Network South East original plan to extend 3rd rail to Weymouth, substituting 4-CIG stock, and transferring the REP+TC arrangement to an electrified service through to Salisbury (or 4-CIG for what terminated there), with the 33s taking one set on to Exeter, was never seen through. Apparently it was a quite close decision.

Why? So for decades we’d be stuck with that arrangement and all the associated faff? You know that would have led to a split service inevitably.

Vs the 159s which having used them repeatedly are very nice, and do the job far more efficiently.

 

[edwin_m]

But the other point is that none of this planning and consultation will start while there is a "presumption against" third rail by ORR.

 

[hwl]

Leaving aside the principles of new third rail installations that have been well explained repeatedly upthread... the Uckfield line will need a substantial sub-station to supply the power (.regardless of type of electrification. How would you feel if this was built next door to your house? That’s why consultation is required.

And finding a suitable bit of DNO network with enough spare capacity to connect it too will be even harder and take even longer!

 

[Bald Rick]

And finding a suitable bit of DNO network with enough spare capacity to connect it too will be even harder and take even longer!

I’m assuming a very long extension lead from Dungeness!

 

[yorksrob]

I’m assuming a very long extension lead from Dungeness!

At least they've still got the Dungeness branch to lay it along !

 

[delticdave]

Which is why modern high performance third rails are mostly made of aluminium?

I know that the DLR uses under-running 3rd rail, with top & side protection, the conductor rail is aluminium with a stainless-steel
contact strip. Each end of the contact strip is formed into a semi-circle & fixed into grooves in the sides of the conductor rail.
Their might be some drawings that could provide a better explanation.......

I don't know if any top-contact aluminium / stainless steel conductor rails have been used in the UK yet.
FWIW, the Siemens test track in Germany has 3rd rail to test their UK-bound trains, with insulation material surrounding the whole rail except the top surface, this might be something to be considered if the remaining un-electrified Southern lines are to be converted.

 

[Tio Terry]

It's a shame that the mid-1980s Network South East original plan to extend 3rd rail to Weymouth, substituting 4-CIG stock, and transferring the REP+TC arrangement to an electrified service through to Salisbury (or 4-CIG for what terminated there), with the 33s taking one set on to Exeter, was never seen through. Apparently it was a quite close decision.

Yes, it was a close decision, but the numbers just didn't add up. Every effort was made to make a good financial case but, in the end, the cost of feeder stations for 3rd rail killed it. You just couldn't provide enough power to run the service without that certain number of feeds.

In respect of aluminium 3rd rail, the contact surface has to be steel for wear reasons and the difference in rate of expansion between steel and aluminium due to changing temperatures has led to the two parting company in some cases. It's fine in tunnels because the temperature change is not so great.

 

[edwin_m]

Yes, it was a close decision, but the numbers just didn't add up. Every effort was made to make a good financial case but, in the end, the cost of feeder stations for 3rd rail killed it. You just couldn't provide enough power to run the service without that certain number of feeds.

Thereby illustrating the problem with third rail as it extends out of urban areas. 25kV would need only one feed, admittedly a much larger one, but more flexibility on where it could be. If Reading-Basingstoke was also electrified on 25kV then that would probably provide redundancy by feeding through from GWML in case of loss of the main feed.

 

[Bald Rick]

Thereby illustrating the problem with third rail as it extends out of urban areas. 25kV would need only one feed, admittedly a much larger one, but more flexibility on where it could be. If Reading-Basingstoke was also electrified on 25kV then that would probably provide redundancy by feeding through from GWML in case of loss of the main feed.

Reading Basingstoke was always planned to be fed from Reading as far as I’m aware.

 

[Surreyman]

Speculation: - If the 159s running Waterloo - Exeter were replaced by new 'DC' Bi Modes, could the existing DC supply/infrastructure from Basingstoke to Waterloo cope with the extra load?

 

[Bald Rick]

Speculation: - If the 159s running Waterloo - Exeter were replaced by new 'DC' Bi Modes, could the existing DC supply/infrastructure from Basingstoke to Waterloo cope with the extra load?

Probably not at present. Would need careful assessment.

 

[Taunton]

Thereby illustrating the problem with third rail as it extends out of urban areas. 25kV would need only one feed, admittedly a much larger one, but more flexibility on where it could be.

As I have consistently described, you don't reduce the number of transformers required, you just move them from the lineside to the underframe of the trains. A 12-car 25Kv emu is going round with three substations underneath it that a DC unit just doesn't have..

Of course, in the never-never land of UK railway financing, if you are Network Rail you couldn't care less if taking cost out of your project sticks it on the rolling stock instead.

 

[hwl]

Thereby illustrating the problem with third rail as it extends out of urban areas. 25kV would need only one feed, admittedly a much larger one, but more flexibility on where it could be. If Reading-Basingstoke was also electrified on 25kV then that would probably provide redundancy by feeding through from GWML in case of loss of the main feed.

There are actually surprisingly few 3rd rail supply connections. Most of the new 3rd rail supplies /renewals come from 400/275kV GSPs with a network of 33kV 3 phase cables to supply the local substations over a wide area (e.g. Wimbledon, New Cross, Croydon, Bolney (a good chunk of Sussex), Ashford etc.) so that not dissimilar to AC...