Great Western Electrification Progress

[MarkyT]

I like the idea of a gym for first class passengers with the treadmill driving the wheels. They could charge extra for that!

A Peloton® franchise: "Don't give up now. Let's climb together..."

 

[D6975]

the problem is - the existing tunnel is 4 miles in length. To bore a new tunnel or build a dedicated bridge would have cost several billion in it's own right.

Typically for this country when a new bridge was built not that long ago, it was built as road only - again. In most other European countries, the equivalent bridge would have been built as a double decker with the trains underneath the road.

 

[TrainBoy98]

Typically for this country when a new bridge was built not that long ago, it was built as road only - again. In most other European countries, the equivalent bridge would have been built as a double decker with the trains underneath the road.

Well that would clearly be too forward-thinking to be allowed in this country... We seem to plan for today and only today, to hell with what the future may bring...
(See Northern being let as a "zero growth" franchise, HS2 being labeled as"unessecary" despite the needed capacity, only one access line to Heathrow and then only from London, to name just a few...)

 

[linuxlad7]

Typically for this country when a new bridge was built not that long ago, it was built as road only - again. In most other European countries, the equivalent bridge would have been built as a double decker with the trains underneath the road.

Salt-water and 25kv are not likely to mix well … how does the channel tunnel do it[/QUOTE]

and would a classic system through the tunnel be more stable than one with ATF?

 

[Brissle Girl]

There is an online article dating back to 2008 on Rail News (sorry I can’t link to it) that says that the water pumped from the Severn Tunnel is springwater, and that corrosion (of the rails) is actually due to the damp environment mixing with diesel fumes. So maybe if everything going through the tunnel was electric it wouldn’t be a problem?

 

[Linda smith]

Good points here - indeed how does the channel tunnel run on 25kv & the severn tunnel struggles?

 

[GRALISTAIR]

Good points here - indeed how does the channel tunnel run on 25kv & the severn tunnel struggles?

Severn Tunnel built in the 1800s , Channel Tunnel built with modern building materials and methods in the 1980s/1990s

 

[Clarence Yard]

It’s a salt water estuary it sits under. When I last went in there, the atmosphere inside the tunnel itself was very warm and salty.

The fans at Sudbrook used to corrode quite quickly and I know the civils at one stage only used specially coated rails in the tunnel.

It’s obviously a very hard environment for any metal object.

 

[w1bbl3]

Good points here - indeed how does the channel tunnel run on 25kv & the severn tunnel struggles?

Well the channel tunnel is a modern concrete segmented tunnel where each piece of the lining is a precast segment that interlocks with the next and has rubber water gaskets around not a brick tunnel from the 19th Century. Modern tunnels are (or can be) essentially dry when well constructed.

The only real options I can see are 1. accept electrification isn't going to work and rely on diesel 2. reline the complete tunnel probably by removing and replacing the existing brickwork with shotcrete and a water proofing membrane 3. if the bore is wide enough install a inner drained lining, probably formed using composites.

Brick lined tunnels are essentially wet spaces as the construction technologies to create dry tunnels didn't exist at the time.

 

[LNW-GW Joint]

I like the BBC comment that the tunnel electrification system was designed by Swiss specialists.
The Swiss wouldn't have much experience of tunnels under salt water estuaries, would they.
The Mersey tunnel 3rd rail DC system must have similar problems.

 

[Thunderer]

Coasting not possible. It is two miles uphill at 1 in 70 each way from the midpoint.

They have just removed 150 years worth of soot from the roof of the tunnel before installing overhead contact bars to reduce acid attack. They should have left it as it would have neutralised salt attack!

The gradient is 1/90 at the Welsh end and 1/100 at the Bristol end. It was designed this way so the gradient favoured heavy coal trains coming out of South Wales.

 

[deltic08]

The gradient is 1/90 at the Welsh end and 1/100 at the Bristol end. It was designed this way so the gradient favoured heavy coal trains coming out of South Wales.

Well that makes all the difference then.

 

[Legolash2o]

Since the rolling stock is diesel hybrid, wouldn't it make sense just to skip electrifying the tunnel or is 4-miles to long for that? Can battery powered trains travel 4 miles?

At a later stage then do as w1bbl3 said and upgrade the tunnel with a water proof membrane, etc.

 

[MarlowDonkey]

Since the rolling stock is diesel hybrid, wouldn't it make sense just to skip electrifying the tunnel or is 4-miles to long for that?

They also had plans to use the London area 387s on an occasional basis if a lot of people needed to be moved to or from Cardiff.

 

[Envoy]

Talking of the 387’’s: surely 387’s or similar should be used as stopping services on the relief’s between Cardiff > Newport & Temple Meads with perhaps extensions to Bath & Swindon? This would enable the Cardiff > Portsmouth trains to be more like proper express services travelling longer distances. The way things are now, the reliefs are wired but nothing is going to use them.

I have often smelt fumes when going through the Severn Tunnel. The sooner all trains through this tunnel are electric, the better.

 

[Dai Corner]

Talking of the 387’’s: surely 387’s or similar should be used as stopping services on the relief’s between Cardiff > Newport & Temple Meads with perhaps extensions to Bath & Swindon? This would enable the Cardiff > Portsmouth trains to be more like proper express services travelling longer distances. The way things are now, the reliefs are wired but nothing is going to use them.

I have often smelt fumes when going through the Severn Tunnel. The sooner all trains through this tunnel are electric, the better.

They might be able to roll down Filton Bank to Temple Meads, but how would they get back up, or get to Bath and Chippenham? Aren't the Reliefs still just 40mph or so?

 

[deltic08]

Since the rolling stock is diesel hybrid, wouldn't it make sense just to skip electrifying the tunnel or is 4-miles to long for that? Can battery powered trains travel 4 miles?

At a later stage then do as w1bbl3 said and upgrade the tunnel with a water proof membrane, etc.

It is already installed in the tunnel and has been for ages.

They also had plans to use the London area 387s on an occasional basis if a lot of people needed to be moved to or from Cardiff.

Electrify from Swindon to Severn Tunnel Junction via Gloucester and they can go that way and keep out of the way of 125mph services. After all it is the only diversion route when Severn Tunnel is closed.

 

[stj]

Regarding 387s these events are mainly at weekends so would there not be any 800s spare.Also arent Cardiffs going to 3 per hour.So there will be extra capacity to Cardiff without using 387s.

 

[PartyOperator]

Would building a new tunnel even be that expensive?

The current tunnel is about 8m wide, or about the same as a single bore HS2 tunnel, estimated to be about £33m per single-tunnel km. On that basis, a new 7km tunnel equivalent to the current one would only be £230m. For another comparison, the contract for cooling water tunnels under the Severn Estuary for the new nuclear power plant at Hinkley point is supposedly about £200m - this includes two 6m diameter intake tunnels 3.5km long and one 7m diameter outfall tunnel 1.85km long (TBM-bored). Most tunnels are more expensive because they're through built up areas and include things like stations. Even compared to the cost of the GWML electrification project so far, this doesn't seem to be a huge amount of money.

Compared to other options mentioned, it would probably be cheaper than electrifying from Swindon to Severn Tunnel Junction via Gloucester for a diversion (assuming 90km of double-track railway at £4m per single-track km it would be £720m). Even at half that cost, a new tunnel would be cheaper. A bridge would be much more environmentally disruptive and also probably more expensive, assuming something similar to the Queensferry Crossing (£1.3bn), or even the Second Severn Crossing adjusted for consumer price inflation (about £600m). And a new tunnel could be built with the existing railway operating and then connected to the network relatively smoothly - relining the current tunnel would be very disruptive and time-consuming and (given the age and unprecedented nature of the task) highly uncertain in cost and likely to suffer delays.

 

[jimm]

Regarding 387s these events are mainly at weekends so would there not be any 800s spare.Also arent Cardiffs going to 3 per hour.So there will be extra capacity to Cardiff without using 387s.

The only extra services between London and South Wales will be a third train per hour in the peaks towards London in the morning and towards Wales in the afternoon. Which is why the plan to use 387s on big event days was devised.

 

[HowardGWR]

I must say I am surprised to read some of the comments on here. We should remember that the GWEP has the goal of electrifying both main lines to Bristol and Cardiff, so any rolling stock purchases need to take account of that. Only the Cardiff to Swansea stretch was cancelled, the others being postponed.
There is no indication that the corrosion problem is incapable of resolution, but there could be some egg on faces, seeing that conditions in the tunnel were known before installation.

 

[Envoy]

They might be able to roll down Filton Bank to Temple Meads, but how would they get back up, or get to Bath and Chippenham? Aren't the Reliefs still just 40mph or so?

Electrification in the Bristol area will happen - it has just been postponed.

Goodness knows why the speed limit on the relief lines is so slow. They cross the same land as the fasts.

 

[linuxlad7]

Typically for this country when a new bridge was built not that long ago, it was built as road only - again. In most other European countries, the equivalent bridge would have been built as a double decker with the trains underneath the road.

Salt-water and 25kv are not likely to mix well … how does the channel tunnel do it

[/QUOTE]

Electrification in the Bristol area will happen - it has just been postponed.

Goodness knows why the speed limit on the relief lines is so slow. They cross the same land as the fasts.

The Severn Tunnel is a geological Joker. Every body (including Sir John Hawkshaw) worried about the deep water channel, (the shoots), where the tunnel was blasted through the carboniferous (iirc) and is pretty stable. its the crappy leaky rock, the littoral margins either side, where the Great Spring and the Salmon Pool give trouble.

 

[coppercapped]

Talking of the 387’’s: surely 387’s or similar should be used as stopping services on the relief’s between Cardiff > Newport & Temple Meads with perhaps extensions to Bath & Swindon? This would enable the Cardiff > Portsmouth trains to be more like proper express services travelling longer distances. The way things are now, the reliefs are wired but nothing is going to use them.

I have often smelt fumes when going through the Severn Tunnel. The sooner all trains through this tunnel are electric, the better.

Wimp! You should have gone through it in steam days!

I remember sitting in the front seats of dmus going through it in about 1958 or 1959. You could only see the light at the end of the tunnel when about 100 yards away through a yellow curtain of smoke. You made sure that all the windows in the carriage were closed before entering. Essentially the drivers were blind through the whole length but there were white lights at track level marking the change in gradient at mid-point.

A whiff of diesel? Enjoy it while you can!

 

[Thunderer]

Well that makes all the difference then.

Sorry if I offended you, I just thought you would like to know the gradients and the story behind it all.

 

[edwin_m]

Goodness knows why the speed limit on the relief lines is so slow. They cross the same land as the fasts.

Where the Reliefs pass over the Mains at Bishton I doubt their alignment is good enough. There may be similar issues elsewhere.

Also track needs relatively less maintenance at low speed and it may be easier to keep the track on the slows maintained by optimising cant for the speeds of freight trains. In the past, and perhaps still, there were probably so many freights that a passenger train would just get stuck behind one anyway.

 

[Envoy]

Where the Reliefs pass over the Mains at Bishton I doubt their alignment is good enough. There may be similar issues elsewhere.

Also track needs relatively less maintenance at low speed and it may be easier to keep the track on the slows maintained by optimising cant for the speeds of freight trains. In the past, and perhaps still, there were probably so many freights that a passenger train would just get stuck behind one anyway.

The Bishton flyover is just one small section of the route from STJ to Cardiff. I see that people are trying to get new stations at *Magor, Llanwern & Cardiff East Parkway (St. Mellons area I presume).
That being so, with all these stops, then surely the steady speed of a freight would have limited impact on a stopping passenger train on the relief’s? I also note that freights are on the ‘slow’ lines between Reading & London & yet stoppers can still be accommodated. That is the sort of thing that I contend should be on the South Wales line between Cardiff, STJ & on to Bristol TM via the new 4 track section entering the city from the north. Huge housing growth is taking place in this area with people commuting both east & westward. *http://magorstation.co.uk

 

[stj]

Talking of the 387’’s: surely 387’s or similar should be used as stopping services on the relief’s between Cardiff > Newport & Temple Meads with perhaps extensions to Bath & Swindon? This would enable the Cardiff > Portsmouth trains to be more like proper express services travelling longer distances. The way things are now, the reliefs are wired but nothing is going to use them.

I have often smelt fumes when going through the Severn Tunnel. The sooner all trains through this tunnel are electric, the better.

I think there was a Swansea-Bath stopper planned using EMUs.But thats not going to happen anytime soon.

 

[edwin_m]

I see that people are trying to get new stations at *Magor, Llanwern & Cardiff East Parkway (St. Mellons area I presume).
That being so, with all these stops, then surely the steady speed of a freight would have limited impact on a stopping passenger train on the relief’s? I also note that freights are on the ‘slow’ lines between Reading & London & yet stoppers can still be accommodated. That is the sort of thing that I contend should be on the South Wales line between Cardiff, STJ & on to Bristol TM via the new 4 track section entering the city from the north. Huge housing growth is taking place in this area with people commuting both east & westward. *http://magorstation.co.uk

There always has been and still is a lot more freight on the South Wales Main Line than east of Reading, as well as far fewer passenger services. So up to now there hasn't really been a need for passenger trains to use the Reliefs except during planned or unplanned closures of the Mains.

The new stations and service, if they happen, might change this. You are probably right that a service on the Reliefs stopping at all these stations would have a similar average speed to a freight. However the extra stops would reduce further the proportion of the Relief lines on which passenger trains would be able to exceed the existing permitted speeds.

 

[deltic08]

Wimp! You should have gone through it in steam days!

I remember sitting in the front seats of dmus going through it in about 1958 or 1959. You could only see the light at the end of the tunnel when about 100 yards away through a yellow curtain of smoke. You made sure that all the windows in the carriage were closed before entering. Essentially the drivers were blind through the whole length but there were white lights at track level marking the change in gradient at mid-point.

A whiff of diesel? Enjoy it while you can!

I remember going through behind steam in the first carriage looking out of the door droplight and hearing the con rod splashing in water as I assume we hit the midpoint with water being thrown over the carriage as if we were taking water from a trough.

Sorry if I offended you, I just thought you would like to know the gradients and the story behind it all.

You didn't. I should have known the gradients off by heart as I have been through enough times in the last 70 years. My great grandfather worked on the tunnel when it was being built. He was a coalminer before that.