Replacing 3rd Rail With OHLE - Benefits

[whhistle]

I've read that 3rd rail is limited to 100mph.

Thinking about the London to Brighton route and area, would an increase in speed to 125 (if OHLE were to be installed) really make much of a difference?

Would there be other benefits?

 

[Aictos]

I've read that 3rd rail is limited to 100mph.

Thinking about the London to Brighton route and area, would an increase in speed to 125 (if OHLE were to be installed) really make much of a difference?

Would there be other benefits?

Well it would be more effective as you wouldn't need sub stations every 1.5 miles plus the obvious speed increases too however you need to bear in mind the various safety requirements that come with 125mph running.

Increasing the line speeds where applicable to 110mph would help especially as you could still use existing rolling stock modified to 110mph running like London Midland did with their Class 350/1s when they rerouted their Crewe services via Weedon a few years ago.

So yes there are places on the former Southern region where it would be advantageous to do however I suspect there are places where it isn't.

 

[edwin_m]

There was a study a few years ago saying it might be worthwhile to convert the third rail network over a long period, starting with the outer parts of the SW main line where the benefits would be greatest (opportunities for high speed running and electric freight, and some of the existing supply equipment needed replacing anyway). However this was at a time before electrification schemes went way over budget. Converting third rail would be more complicated than just installing OLE and bring less benefit, so the idea is likely to be dead for the foreseeable future.

 

[Journeyman]

London to Brighton is very congested, and most trains stop pretty regularly, so I really doubt 110/125mph operation would be practical or deliver any significant benefits. Rapid acceleration is more important on a route like that.

When the Bournemouth line was electrified in 1967, BR did consider using 25kV instead of third rail, but balked at the costs and complications of installing the wires on the approaches to Waterloo. This was a good ten years before BR's first dual-voltage rolling stock appeared.

 

[LLivery]

I'll always endorse OHLE conversion but nowhere in the Southern Region needs to be 125mph. All that would do is reduce capacity, no?

 

[AM9]

I'll always endorse OHLE conversion but nowhere in the Southern Region needs to be 125mph. All that would do is reduce capacity, no?

The benefit of 25kVac over 750VDC on what is really an outer-suburban network is more with acceleration and better regenerative braking rather than speeds faster than 100mph.
All the modern stock running on 3rd rail is power-limited by software. The better acceleration would improve route capacity as paths could be closer, especially decent signalling. There would also probably be fewer track circuit failures than currently endured.

 

[Bald Rick]

Plenty of benefits, but higher top speed is not one of them. At least for the Brighton Line.

 

[Aictos]

Plenty of benefits, but higher top speed is not one of them. At least for the Brighton Line.

However as @AM9 has pointed out, better acceleration and better regenerative braking is certainly one of these benefits right?

 

[Bald Rick]

However as @AM9 has pointed out, better acceleration and better regenerative braking is certainly one of these benefits right?

Oh yes:

Better acceleration
Better regen
Safer
Cheaper infrastructure maintenance
More reliable infrastructure overall
Reduced disruption due to external events

 

[Aictos]

Oh yes:

Better acceleration
Better regen
Safer
Cheaper infrastructure maintenance
More reliable infrastructure overall
Reduced disruption due to external events

Also more trains can run as there will be more paths to fit in or have I got that part wrong?

 

[Bald Rick]

Also more trains can run as there will be more paths to fit in or have I got that part wrong?

Yes, you have that wrong.

 

[Aictos]

Yes, you have that wrong.

Well I'm not perfect

However OHL would have advantages over 3rd Rail especially between Bournemouth and Weymouth as the power supply is rather restricted down there as I understand it?

That said, would they actually electrify existing non electrified lines first to OHL then convert existing 3rd rail routes or do it the other way round?

 

[Bald Rick]

However OHL would have advantages over 3rd Rail especially between Bournemouth and Weymouth as the power supply is rather restricted down there as I understand it?

The power supply is restricted a the electrification was done to a budget, and thus fewer substations were installed (and possibly only a 11kV feeder like on the Hastings line?)

Therefore the obvious way to increase power is to put in more substations.

 

[Belperpete]

There was a study a few years ago saying it might be worthwhile to convert the third rail network over a long period, starting with the outer parts of the SW main line where the benefits would be greatest (opportunities for high speed running and electric freight, and some of the existing supply equipment needed replacing anyway). However this was at a time before electrification schemes went way over budget. Converting third rail would be more complicated than just installing OLE and bring less benefit, so the idea is likely to be dead for the foreseeable future.

The SW mainline is really the only Southern line that might benefit from conversion to 25kV. However, the costs would be considerable, and the benefits fairly limited. With only a limited pot of money available for improvements, there are many other things that would give a far better return.
The Southern chose to rip its overheads out, and replace them with third rail, for good reasons.

 

[4-SUB 4732]

I think they should convert more routes into third rail, to be honest. I don't care what the ORR say, they are deliberately putting up obstacles.

Let's see...

- Bidston to Wrexham Central
- Ellesmere Port to Helsby
- Hurst Green to Uckfield
- Ashford Intl to Ore
- Reigate to Guildford
- Ash to Wokingham
- Hunts Cross to Warrington Central
- Kirkby to Wigan Wallgate
- Ormskirk to Preston

 

[Belperpete]

Oh yes:

Better acceleration
Better regen
Safer
Cheaper infrastructure maintenance
More reliable infrastructure overall
Reduced disruption due to external events

I am assuming that this was written with a large slice of tongue in cheek? Having been borne and brought up in third rail territory, and moved to OLE land, my experience is that third rail services are far more reliable. When OLE areas are suffering from ice on the wire, and consequent dewirings, third rail areas seem to keep soldiering on (provided the de-icing trains are run properly). Displaced conductor rails do occur, but far less frequently than problems with the OLE. And when they do occur, they are far less disruptive. A fault on the OLE, such as a wire down, often shuts both lines, to all traffic, often for long periods of time, whereas a displaced conn rail usually only shuts one line, only to electric traction, and is usually fixed relatively quickly.
Unlike OLE, third rail electrification can be installed without significant civil engineering works, and with minimal disruption to traffic.
I am not convinced that third rail is significantly less safe than OLE, judging by the number of people who seem to get electrocuted in OLE areas. I think that the third rail is more "in your face" when on and about the line, so you take more care, whereas it is easy to forget about the OLE as you are not routinely having to avoid it.

 

[4-SUB 4732]

I agree. I live in Third Rail land and travel across the country and worked on the MML and ECML. The overhead wires, whilst very nice, are absolutely knackered the minute a small plastic bag or balloon flies off into them; or when there's high winds, when it's too hot (sagging), when it's covered in ice etc. Basically, the third rail is definitely difficult during ice but can be managed with appropriate de-icing. Yes, it doesn't have the high speeds of the overheads but when you consider where it operates and what sort of services run on it, it's perfect.

 

[baz962]

Well no one has mentioned the snatching over third rail gaps and points , make my teeth fall out and my wig slip .

 

[4-SUB 4732]

What of those lovely neutral sections...

... Where things often go wrong!

 

[AM9]

I agree. I live in Third Rail land and travel across the country and worked on the MML and ECML. The overhead wires, whilst very nice, are absolutely knackered the minute a small plastic bag or balloon flies off into them;

How many times does that happen per year then?

... or when there's high winds, when it's too hot (sagging), when it's covered in ice etc.

All OLE installed or replaced in the UK since the '60s, has been fitted with automatic tensioners, either with weights or spring types like Tensorex. In areas of frequent high winds, higher wire tension or more frequent supports reduces the risks of misalignment and subsequent damage.

... Basically, the third rail is definitely difficult during ice but can be managed with appropriate de-icing.

Despite extensive icing, it still doesn't do much for reliability of either slow or intense services.

... Yes, it doesn't have the high speeds of the overheads but when you consider where it operates and what sort of services run on it, it's perfect.

The current speed limit of 3rd rail operation is a compromise between a reasonable maximum operating speed for shorter outer suburban services (which is also in-part near the limit of lower voltage power supplies), and reduced reliability of current collection, as well as increased shoe and track damage.
But above all, the removal of the hazards of exposed high voltages at ground level to staff and public completely trumps the few disadvantages of OLE compared with 3rd rail.

 

[AM9]

I think they should convert more routes into third rail, to be honest. I don't care what the ORR say, they are deliberately putting up obstacles.

Let's see...

- Bidston to Wrexham Central
- Ellesmere Port to Helsby
- Hurst Green to Uckfield
- Ashford Intl to Ore
- Reigate to Guildford
- Ash to Wokingham
- Hunts Cross to Warrington Central
- Kirkby to Wigan Wallgate
- Ormskirk to Preston

It just as well that somebody puts a value on rail staff and passenger safety. So forget anything other than a few crossovers or sidings being added to the 3rd rail network.

 

[AM9]

The SW mainline is really the only Southern line that might benefit from conversion to 25kV. However, the costs would be considerable, and the benefits fairly limited. With only a limited pot of money available for improvements, there are many other things that would give a far better return.

The BML south of Merstham area, parts of the south-Eastern mainlines would also benefit. Much of the costs would be defrayed against the necessary replacement of existing DC installations and many of the structures over the lines which are well over 100 years old.

The Southern chose to rip its overheads out, and replace them with third rail, for good reasons.

The LB&SCR 6600V ac OLE went as far as South Croydon, There were plans to electrify the BML, only halted by the 1923 grouping. In 1925, the Southern Railway decided to convert the ac lines to 3rd rail dc as both the SE and SW parts of their network were already DC, (mainly following US practice). There was no technical justification for it. The SWML wasn't electrified beyond the Alton line junction until 1966.

 

[Aictos]

The power supply is restricted a the electrification was done to a budget, and thus fewer substations were installed (and possibly only a 11kV feeder like on the Hastings line?)

Therefore the obvious way to increase power is to put in more substations.

Which of course is costly as 25kV AC is far more effective as it needs less sub stations for the same if not more amount of power available to the rolling stock.

 

[brad465]

The Beast from the east this year taught me that while 3rd rail and snow is an issue, snow still physically blocks lines and damages rolling stock used in such conditions, whether 3rd rail, OHLE, or no electrification.

The SWML from Woking to Basingstoke, and maybe to Eastleigh/Salisbury via WEML (latter not electrified anyway), could get 110-125mph running with OHLE and rolling stock changes, but I doubt that would happen anytime soon

 

[swt_passenger]

The SWML from Woking to Basingstoke, and maybe to Eastleigh/Salisbury via WEML (latter not electrified anyway), could get 110-125mph running with OHLE and rolling stock changes, but I doubt that would happen anytime soon

Not possible unless you lose all the freight. There’s been many previous discussions about this...

 

[big all]

The BML south of Merstham area, parts of the south-Eastern mainlines would also benefit. Much of the costs would be defrayed against the necessary replacement of existing DC installations and many of the structures over the lines which are well over 100 years old.

The LB&SCR 6600V ac OLE went as far as South Croydon, There were plans to electrify the BML, only halted by the 1923 grouping. In 1925, the Southern Railway decided to convert the ac lines to 3rd rail dc as both the SE and SW parts of their network were already DC, (mainly following US practice). There was no technical justification for it. The SWML wasn't electrified beyond the Alton line junction until 1966.

nearly right
the overhead went as far as the depot [now closed ]where i got my first driving job at coulsdon north beside the quarry line in the space between coulsdon town[smitham] and the end off the sidings at marlpit lane at the end coulsdon south station
the space now occupied by the coulsdon bypass road

electrifying from hurstgreen and reopening the uckfeild to lewis section would be far more usefull capacity wise to the brighton line

 

[brad465]

Not possible unless you lose all the freight. There’s been many previous discussions about this...

Oh right, so as to understand it better, what such factors make freight the reason specifically? My instinct is influence on the track/trackbed and/or line capacity as a whole, but I maybe wrong :/

Obviously freight will never be lost due to Southampton Docks

 

[swt_passenger]

Oh right, so as to understand it better, what such factors make freight the reason specifically? My instinct is influence on the track/trackbed and/or line capacity as a whole, but I maybe wrong :/

Obviously freight will never be lost due to Southampton Docks

It’s simply a very busy two track railway, and if the passenger trains speed up significantly they’ll run into either the slow freights or the all stations stoppers in front of them

 

[Bald Rick]

I am assuming that this was written with a large slice of tongue in cheek? Having been borne and brought up in third rail territory, and moved to OLE land, my experience is that third rail services are far more reliable. When OLE areas are suffering from ice on the wire, and consequent dewirings, third rail areas seem to keep soldiering on (provided the de-icing trains are run properly). Displaced conductor rails do occur, but far less frequently than problems with the OLE. And when they do occur, they are far less disruptive. A fault on the OLE, such as a wire down, often shuts both lines, to all traffic, often for long periods of time, whereas a displaced conn rail usually only shuts one line, only to electric traction, and is usually fixed relatively quickly.
Unlike OLE, third rail electrification can be installed without significant civil engineering works, and with minimal disruption to traffic.
I am not convinced that third rail is significantly less safe than OLE, judging by the number of people who seem to get electrocuted in OLE areas. I think that the third rail is more "in your face" when on and about the line, so you take more care, whereas it is easy to forget about the OLE as you are not routinely having to avoid it.

I agree. I live in Third Rail land and travel across the country and worked on the MML and ECML. The overhead wires, whilst very nice, are absolutely knackered the minute a small plastic bag or balloon flies off into them; or when there's high winds, when it's too hot (sagging), when it's covered in ice etc. Basically, the third rail is definitely difficult during ice but can be managed with appropriate de-icing. Yes, it doesn't have the high speeds of the overheads but when you consider where it operates and what sort of services run on it, it's perfect.

Nope, it was written through many years hard experience of managing operations and maintenance in both OLE and third rail areas.

Note that I didn’t say that OLE is more reliable than 3rd rail. I wrote “more reliable infrastructure overall”.

Yes wires come down, or there are other faults with it, but mile for mile my experience is that it is broadly the same as faults with the con rail. Note that it is pretty obvious when there is a service affecting fault with the OLE, but not often obvious with the con rail.

Three other major things.

1) Whenever there is a trespasser on the track (or worse), or obstruction on the line, in 3rd rail land, the power comes off. This often strands trains far from the incident. This does not happen in OLE areas. Only tonight my train was delayed by a trespasser in an OLE area. We passed through at caution. Had that been in a third rail area, all lines would have been stopped for at least 30 minutes.

2) When maintaining the track in third rail areas, for anything but inspection and the most minor works, the power comes off. This takes time and takes about an hour off ‘productive’ time compared to OLE. When you only have about 4hours to start this is a 25% loss of productivity. Which means either it costs 25% more, or it is not done as well, causing more faults down the line. Or a combination of both.

3) there is a lot of kit trackside and in the signalling on third rail areas to deal with return currents. It often goes wrong. It also causes a fair proportion of incidents reported as ‘signal failures’ - yes it’s part of the signalling but it is only there for the third rail power system. This is just not an issue in OLE areas.

 

[trainmania100]

Quite a lot of low bridges between wivelsfield and Brighton, each one would need reconstructing or the UNits would need VERY low pantrogaphs
Wouldn't be viable option to upgrade that part of line