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Ah, my first project when I started as a graduate engineer... An interesting feasibility study, but like you say would have been very expensive, and so much more so today. I think there was a plan for a triple grade-separated junction somewhere. And it was linked to Railtrack's mad plan to run an additional 7-8 trains per hour from Heathrow onto the northern section of the Circle line. Unsurprising it never saw the light of day.
It would be better if the main line was moved into the tunnels, then the current day mainline can be for semi fast and freight movements and the relief can be solely for the Elizabeth Line.
Yes, the current line has platforms. The fast tracks don't need platforms, and building platforms in tunnels is very expensive. So it is easier (and lot cheaper) to build the new tunnels without platforms
Though I’d rather have that the new express tunnel went via Heathrow Airport that way Heathrow can obtain proper intercity train connections to the West of England and South Wales. It’s insane that the UK’s busiest airport has ZERO intercity trains.
yes, and logical thing is to build it in the basement of where terminal 3 is when it is knocked down, as T3 is no longer fit for purpose (T3 is the old Oceanic terminal that originally opened in 1961 when planes were lot smaller, hence why it is cramped with lots of random extensions)
Twyford station itself would need a little work but broadly you can six track on last easily after Maidenhead. Pointless tunnelling to Reading, it's a lot of mileage and open fields.
Actually it's questionable if actually need 6 tracks west of Heathrow, or if just only need a 5th track. Ideally the slow / relief lines would be 3 tracks with the centre of the 3 reversible and used for overtaking or at busy times, or when slow freight needs to be slotted in.
I've been looking at the GWML again, and gauging which sections of track looked reasonably feasible to 6-track. My answer is from just west of Langley to just east of Southall. The optimist in me would through in Hanwell and a rebuilding of the Wharncliffe viaduct, but I'm ignoring that for now.
It’s hardly an original idea though, there’s been a few speculative GWML 6 tracking threads. I believe they have all ended up with explanations as to why it’s just too costly.
Is there any evidence for that? Clearly the HS2 connection idea was cancelled when they reasoned there wasn’t enough demand. The high speed link is to use HEx via Old Oak Common.
How far from the current GWML will the third runway at Heathrow be? Could there be a slight diversion to serve the new third runway terminal, and would there be some sort of internal link from the third runway to the main airport?
In reality 6 tracking is only neccesary to Heathrow Junction. It's mainly between Heathrow Junction and the Elizabeth Line portal where capacity becomes a huge problem.
When you remove one bottleneck, is the next immediately beyond? It depends on how western access to Heathrow helps, and if that could include a flying Dolphin junction.
A freight tunnel is probably alot more difficult when it comes to capacity. Under long streches of tunnels used by freight trains you're only allowed to run 1 train at a time.
The chances of ATO being fitted to a sufficiently safe degree on the legacy GWML is virtually nil, so are you proposing that every freight train stop to drop the driver off and pick another up at each end?
And, of course, there's plenty of freight that would need to stay on the surface to access the various terminals on the GWML between Acton and Iver.
The chances of ATO being fitted to a sufficiently safe degree on the legacy GWML is virtually nil, so are you proposing that every freight train stop to drop the driver off and pick another up at each end?
Yes, essentially driver disembarks at the west end, presses a plunger and (assuming the route sets) the train drives itself to Acton Yard.
Whether the driver that collects the train (assuming its not just going to Acton yard) at the other end is the same driver (who took another route) or not is a question I leave to the reader/operator.
Is there a maximum length of tunnel through which diesel trains can travel? If so, since I assume most freight is diesel hauled, it would make sense not to send freight down the tunnel.
This is labelled as fantasy, so what I'd do is expand Euston HS2 to become the high speed hub for London (let's assume the eastern leg happens as well, so probably something like 16 platforms). Then 4 track it out to somewhere like Aylesbury and build a new line via Oxford Parkway (maybe with a station there, sadly it's a bit far for "Shin Oxford" to also have platforms at Wolvercote on the Cherwell/ Cotswold lines but that'd be ideal for the interchange) to join the GWML around Swindon. Should clear most of the fastest trains out to permit a bit more to run on the existing lines.
Is there any evidence for that? Clearly the HS2 connection idea was cancelled when they reasoned there wasn’t enough demand. The high speed link is to use HEx via Old Oak Common.
Nope I'm just operating under the timescale in which an intercity service via heathrow will inevitably get built. So probably some time after the full HS2 Y network.
The question was whether the advent of the Elizabeth line, and it’s success in terms of passenger numbers, had changed the equation in terms of potential six tracking of the GWML. Which it hasn’t.
That is a fair point. I mean the government does have a financial problem; it always does but at present I’d suggest the calls on government funding (Welfare, helath service, defence in particular) puts it in the most difficult position it has seen since 2008.
The railways financial position is dire, and HMT have no doubt made it clear there is no more money to accommodate the rather large revenue shortfall.
I don't disagree with you there. But since this is a speculative thread, I was hoping you'd understand that I'm not asking you whether this is a project we should be building right now, but rather whether it's a fitting vision for the future of the network. So the question of whether the government is broke isn't relevant to the question at hand. I'd like to hear something different from you for once.
For what it’s worth I think there is some merit in 2 additional tracks from somewhere around Acton to somewhere around Airport Jn, and for those tracks not to have platforms on them. And for those tracks to retain access to Acton Yard, and all the freight facilities at Hanwell, Southall etc. Certainly this has more merit than building 2 tracks from, say, Harrogate to Ripon.
Ah, my first project when I started as a graduate engineer... An interesting feasibility study, but like you say would have been very expensive, and so much more so today. I think there was a plan for a triple grade-separated junction somewhere. And it was linked to Railtrack's mad plan to run an additional 7-8 trains per hour from Heathrow onto the northern section of the Circle line. Unsurprising it never saw the light of day.
For what it’s worth I think there is some merit in 2 additional tracks from somewhere around Acton to somewhere around Airport Jn, and for those tracks not to have platforms on them. And for those tracks to retain access to Acton Yard, and all the freight facilities at Hanwell, Southall etc. Certainly this has more merit than building 2 tracks from, say, Harrogate to Ripon.
So additional freight tracks rather than fast (bypass tunnel) ones? I think it’d be very difficult between Ealing Bdy and Southall.
Surely a simple no tunnel, uniform pattern / profile pair of tracks would be far cleaner, and cheaper?
I’d go to at least after Slough so you could rework that station for turning and stopping more services.
Possibly reviving my favourite slight crayola of getting Crossrail over to Windsor - but maybe a different way of direct services from the current Main lines / p2 would be far more realistic.
So additional freight tracks rather than fast (bypass tunnel) ones? I think it’d be very difficult between Ealing Bdy and Southall.
Surely a simple no tunnel, uniform pattern / profile pair of tracks would be far cleaner, and cheaper?
I’d go to at least after Slough so you could rework that station for turning and stopping more services.
Possibly reviving my favourite slight crayola of getting Crossrail over to Windsor - but maybe a different way of direct services from the current Main lines / p2 would be far more realistic.
To be fair is there any way we could remodel the junction at Slough so that Elizabeth Line can cross onto the Windsor branch? (grade separated of course)
The current EL problem is not freight, it's maintaining two speed profiles and trying to serve inner and outer markets simultaneously (or at least maintaining the appearance of doing so).
If the EL can operate a uniform inner speed profile, then it can easily coexist with freight and have a modest frequency increase. EL and freight staying on existing reliefs is not a problem.
If a 6-track railway is buildable and fundable, then HEx and the outer market can share one pair of tracks, non-stop until Slough.
The way to achieve best bang for buck for building a pair of tunnels (it will be tunnels, because there are things called laws and democracy here) is not to incur any station expenses and to serve the trains best placed to benefit from any speed increase, and that's the first-stop-Reading LDHSs.
To be fair is there any way we could remodel the junction at Slough so that Elizabeth Line can cross onto the Windsor branch? (grade separated of course)
The current EL problem is not freight, it's maintaining two speed profiles and trying to serve inner and outer markets simultaneously (or at least maintaining the appearance of doing so).
If the EL can operate a uniform inner speed profile, then it can easily coexist with freight and have a modest frequency increase. EL and freight staying on existing reliefs is not a problem.
If a 6-track railway is buildable and fundable, then HEx and the outer market can share one pair of tracks, non-stop until Slough.
The way to achieve best bang for buck for building a pair of tunnels (it will be tunnels, because there are things called laws and democracy here) is not to incur any station expenses and to serve the trains best placed to benefit from any speed increase, and that's the first-stop-Reading LDHSs.
With money anything is possible, but this would not be good use of money.
The current EL problem is not freight, it's maintaining two speed profiles and trying to serve inner and outer markets simultaneously (or at least maintaining the appearance of doing so).
If the EL can operate a uniform inner speed profile, then it can easily coexist with freight and have a modest frequency increase. EL and freight staying on existing reliefs is not a problem.
If a 6-track railway is buildable and fundable, then HEx and the outer market can share one pair of tracks, non-stop until Slough.
The way to achieve best bang for buck for building a pair of tunnels (it will be tunnels, because there are things called laws and democracy here) is not to incur any station expenses and to serve the trains best placed to benefit from any speed increase, and that's the first-stop-Reading LDHSs.
I don't think there would be much at all in the way of journey time savings from a fast tunnel between the vicinity of Acton Main Line (on approach to Old Oak Common) and only Slough.
The line speed is already pretty high and its only ~25km, you might save a couple of minutes, but if that, the capacity increase of stacking trains in the fast tunnels and a "modest" frequency increase on the Elizabeth Line is all you have to show for it I don't think the business case would look that great.
Even if we can force inner suburban Elizabeth Line trains to a similar average speed to very heavy, low power aggregate trains, there will still be major lost capacity because the sectional running times will still be very different once the station stops are stripped out. It doesn't matter if the freight train takes a similar average amount of time to travel the route (in a time trial) if the passenger train keeps accelerating into the back of it as it plods along. A passenger train with stops oscillates around its theoretical average speed path by a significant margin.
If we separate the freight out we can put 18+ trains per hour down the fast lines (with resignalling obviously) and run as many Crossrail trains as the core can take on the reliefs.
I've tried to get a count on the number of freight facilities inside of Slough, and there doesn't seem to be that many, and at least a couple are connected via extended branches that could be connected to a tunnel system for freight trains.
EDIT:
To clarify what I'm saying, I think any successful solution has to completely separate the freight operations (or at least the vast majority) from the passenger operations.
Freight will need a track or (probably) a pair of tracks entirely dedicated to it, otherwise I don't think the cost of the infrastructure works could be justified.
I personally think a freight tunnel si the way to go, but a fast tunnel could probably do it.
But I think we need three track pairs, fast trains, Crossrail trains and freight trains, not an awkward mix. Apparently the fastest Elizabeth line train only skips three stops as it is (I make it Iver, Hanwell and Acton Main Line), and frequency increase could quite plausibly wipe out any journey time advantage there.
It’s true that due to the squished pattern, the semi fasts don’t offer huge time savings. It’s psychological, and plain old bums on seats.
If a set of services were fast from OOC to Heathrow Central and West Drayton or Slough, that would definitely negate the need for semi Slough calls etc - and provide a nice saving.
That said, it’s hard to justify skipping Ealing Broadway and also Hayes in this speculative scenario. Fasts are under them - and they likely justify all calls.
But in this semi scenario you could look at getting out to Didcot, Newbury and even Basingstoke. Probably not on EL (in Japan they would make it work - Reading = Omiya etc) - but take the outer semi fast. And add service to the further west.
It’s true that due to the squished pattern, the semi fasts don’t offer huge time savings. It’s psychological, and plain old bums on seats.
If a set of services were fast from OOC to Heathrow Central and West Drayton or Slough, that would definitely negate the need for semi Slough calls etc - and provide a nice saving.
That said, it’s hard to justify skipping Ealing Broadway and also Hayes in this speculative scenario. Fasts are under them - and they likely justify all calls.
But in this semi scenario you could look at getting out to Didcot, Newbury and even Basingstoke. Probably not on EL (in Japan they would make it work - Reading = Omiya etc) - but take the outer semi fast. And add service to the further west.
True, but if we could give Elizabeth line the reliefs to themselves (so the platforms could rebuilt for Level boarding) we could do something like 8tph to Heathrow off Elizabeth line all day and 8tph offpeak to stations beyond Hayes and Harlington (compared to 4 now) and 14-16tph during peak.
I think the psychological advantage of skipping some calls would give way to the psychological advantage of much shorter waiting times.
I don't think there would be much at all in the way of journey time savings from a fast tunnel between the vicinity of Acton Main Line (on approach to Old Oak Common) and only Slough.
The line speed is already pretty high and its only ~25km, you might save a couple of minutes, but if that, the capacity increase of stacking trains in the fast tunnels and a "modest" frequency increase on the Elizabeth Line is all you have to show for it I don't think the business case would look that great.
Even if we can force inner suburban Elizabeth Line trains to a similar average speed to very heavy, low power aggregate trains, there will still be major lost capacity because the sectional running times will still be very different once the station stops are stripped out. It doesn't matter if the freight train takes a similar average amount of time to travel the route (in a time trial) if the passenger train keeps accelerating into the back of it as it plods along. A passenger train with stops oscillates around its theoretical average speed path by a significant margin.
If we separate the freight out we can put 18+ trains per hour down the fast lines (with resignalling obviously) and run as many Crossrail trains as the core can take on the reliefs.
I've tried to get a count on the number of freight facilities inside of Slough, and there doesn't seem to be that many, and at least a couple are connected via extended branches that could be connected to a tunnel system for freight trains.
EDIT:
To clarify what I'm saying, I think any successful solution has to completely separate the freight operations (or at least the vast majority) from the passenger operations.
Freight will need a track or (probably) a pair of tracks entirely dedicated to it, otherwise I don't think the cost of the infrastructure works could be justified.
I personally think a freight tunnel si the way to go, but a fast tunnel could probably do it.
But I think we need three track pairs, fast trains, Crossrail trains and freight trains, not an awkward mix. Apparently the fastest Elizabeth line train only skips three stops as it is (I make it Iver, Hanwell and Acton Main Line), and frequency increase could quite plausibly wipe out any journey time advantage there.
In the current timetable every 'fast' EL service costs two paths between Hayes and Paddington. Remove that speed differential then your peak capacity instantly grows from 12tph (as is now) to 18tph, split say 8tph Heathrow, 6tph Slough, 4 West Drayton starter. Off-peak can be back to 12tph for more freight.
You overstate the impact of freight on a consistent-pattern metro service. It's freight that needs to be slowed to fit between the stopping passenger services. You'd need a bit of yellow signal running but that's manageable.
The 18tph EL would be exclusively for inside of Slough, calling at all stations.
Slough, Burnham, Taplow, Maidenhead and Twyford would then gain dedicated 6-8tph on the existing Mains, which would be a considerable speed and capacity boost from today. These would operate alongside HEx.
The new fast tracks without the HEx's and semi-fasts would then allow
- new 2tph Bristol super-fasts
- 2tph Didcots without Maidenhead (and Slough) punters
- Newburys going up from 1tph to 2tph
One thing that is a bit forgotten in this debate is that 'parallel' to the GWML, there are trains which take over an hour to reach Wokingham from London, and which take over an hour to get from Reading to Clapham Junction, yet no intervention or relief that promises a faster journey.
Any 'solutions' should surely look at the circumstances of the whole corridor.
Indeed, all across the Southern region there are slow routes into London which their users would love to be upgraded with whatever capacity enhancements can be made.
True, but if we could give Elizabeth line the reliefs to themselves (so the platforms could rebuilt for Level boarding) we could do something like 8tph to Heathrow off Elizabeth line all day and 8tph offpeak to stations beyond Hayes and Harlington (compared to 4 now) and 14-16tph during peak.
You can timetable certain lines for certain trains, but on Sundays and following unplanned events other trains will be using it. So it isn’t possible to rebuild platforms.
You can timetable certain lines for certain trains, but on Sundays and following unplanned events other trains will be using it. So it isn’t possible to rebuild platforms.
Indeed. National Rail metros will always be quasi metros (they will be good metros on a typical weekday daytime but will have to make compromises at other times that pure metros do not), and they will have to work within the Network Code, which means they need to respect that the infrastructure they use needs to be useful for all railway users.
You can timetable certain lines for certain trains, but on Sundays and following unplanned events other trains will be using it. So it isn’t possible to rebuild platforms.
Well that is the practice now, but it is not an immutable law of the universe.
It would be entirely possible to physically separate the relief lines from the rest of the network and leave them connected solely to the Crossrail core. We might debate the relative merits of that, but it is not impossible that it be so.
For example, if the main lines are closed, you could turn the fast trains at the western end of the closure and carry everyone on Elizabeth line trains.
== Doublepost prevention - post automatically merged: ==
Indeed. National Rail metros will always be quasi metros (they will be good metros on a typical weekday daytime but will have to make compromises at other times that pure metros do not), and they will have to work within the Network Code, which means they need to respect that the infrastructure they use needs to be useful for all railway users.
I don't think the Network Code has quite that much power to prevent any infrastructure modification that might restrict the usefulness of the railway to anyone. Especially as in this scenario freight would receive far more access to the GWML corridor than before, with a pair of freight lines largely reserved to it.
In any case, if the relief lines were to be transferred to the Elizabeth line full time, it seems likely that the infrastructure would be transferred from the influence of the Network Rail Network Code to the CCOS Network Code.
== Doublepost prevention - post automatically merged: ==
In the current timetable every 'fast' EL service costs two paths between Hayes and Paddington. Remove that speed differential then your peak capacity instantly grows from 12tph (as is now) to 18tph, split say 8tph Heathrow, 6tph Slough, 4 West Drayton starter. Off-peak can be back to 12tph for more freight.
You overstate the impact of freight on a consistent-pattern metro service. It's freight that needs to be slowed to fit between the stopping passenger services. You'd need a bit of yellow signal running but that's manageable.
I don't think the problem is top speed as such, I think the problem is that many of the eastbound stone trains have power to weight ratios (at rail) well below 1hp/t. They seem to operate 3000+ tonne trains with only a Class 66.
If the freight train has to brake for any reason its going to end up stuck in the metaphorical treacle whilst trains pile up behind it.
Accelerating from 8m/s (~18mph) to 18m/s (~40mph) at 500W/tonne, ignoring all rolling and air resistance, would take over four minutes. (EDIT: Coincidentally the average speed of Elizabeth line from Slough to Paddington is about 40mph)
Consequently, I am sceptical that a high intensity timetable can be operated reliably, especially once it is exposed to the vagaries of passenger operations.
On dedicated freight lines the trains can just plod along as they will, since they all have generally similar performance characteristics and no pressing need to stop a lot.
It'd probably be workable with IORE style high power, high tractive effort electrics, but that doesn't seem likely to happen.
The 18tph EL would be exclusively for inside of Slough, calling at all stations.
Slough, Burnham, Taplow, Maidenhead and Twyford would then gain dedicated 6-8tph on the existing Mains, which would be a considerable speed and capacity boost from today. These would operate alongside HEx.
The new fast tracks without the HEx's and semi-fasts would then allow
- new 2tph Bristol super-fasts
- 2tph Didcots without Maidenhead (and Slough) punters
- Newburys going up from 1tph to 2tph
Given all the political trouble we had over the Elizabeth line not making it to Reading from Maidenhead, I'm not sure cutting it off at Slough is going to go down very well.
I'd say the political pressure is in the opposite direction - more Elizabeth line, not less.
I don't think the problem is top speed as such, I think the problem is that many of the eastbound stone trains have power to weight ratios (at rail) well below 1hp/t. They seem to operate 3000+ tonne trains with only a Class 66.
My understanding is that the second locomotive is often dead-in-train to reduce the shunting requirements at the destination. Given the lack of a multiple unit system capable of communicating through the consist, the second locomotive is just cargo. Additionally I was under the impression that a jumbo train was much heaveir than ~3200t, often up to 4400t+ trainweight.
With all this talk about headways etc, I think it would be relevant to mention that at least some part of the GWML is fitted with ETCS. Do 345s use this at all?
With all this talk about headways etc, I think it would be relevant to mention that at least some part of the GWML is fitted with ETCS. Do 345s use this at all?
345s and the Heathrow Express trains both use ETCS. However its only fitted between just east of Ealing Broadway to Stockley Jn and Heathrow, and the block sections are just the same as signal sections so the only capacity benefit currently comes from not needing approach control on certain signals for trains running in ETCS.
The headways on the GWML are already down to 2 minutes in places so full signals away ETCS L2 wouldn't get much more capacity out of it. And Signals away L2 is a very long way away on the GWML.
I’m not sure what the issue is. This line will be significantly shorter than HS2 and HS2’s problems lie with terrible project management and overengineering.
