Fantasy - GWML west of Old Oak Common

[squingo44]

Given the absolute requirement to serve the aggregates sidings and depots, then theyll need to be on the surface.

Yes but you're not necessarily putting the freight trains through the tunnel are you?

== Doublepost prevention - post automatically merged: 14 Sep 2026 ==

I don't think you're giving enough weight to the idea of putting the Elizabeth line in a tunnel with underground stations. Tunnel from OOC to east of Southall, 6-track from Southall to west of Langley. Extend to Slough if you're willing to do disruptive work in Slough town centre.

It would be able to support 24 TPH west of OOC, potentially split between OOC and Langley. Outer semi-fast commuter services could go non-stop from Slough to Old Oak Common, and terminate at Paddington with 2-3 platforms - leaving 9-10 platforms for the two fast lines, enough to support a solid 18 TPH if a flyover were inserted into the station approach. Then you could have up to 16 TPH semi-fast services from Didcot/Newbury/Reading stopping at the outer stations, as well as any potential Heathrow express services.

I'd give the lizzie line a timetable of 8 TPH each of Langley-Shenfield, Langley-Abbey Wood, and Heathrow-Abbey Wood.

Surely a couple of underrgound stations would be cheaper and more suitable than a brand new express tunnel extending much further, especially when we already have a perfectly functioning fast line between Paddington and Reading? We need to segregate the stoppers out from the semi-fasts and the freight services, so we can move the last semi-fasts off the main lines entirely.

 

[Mgameing123]

Yes but you're not necessarily putting the freight trains through the tunnel are you?

== Doublepost prevention - post automatically merged: 14 Sep 2026 ==

I don't think you're giving enough weight to the idea of putting the Elizabeth line in a tunnel with underground stations. Tunnel from OOC to east of Southall, 6-track from Southall to west of Langley. Extend to Slough if you're willing to do disruptive work in Slough town centre.

It would be able to support 24 TPH west of OOC, potentially split between OOC and Langley. Outer semi-fast commuter services could go non-stop from Slough to Old Oak Common, and terminate at Paddington with 2-3 platforms - leaving 9-10 platforms for the two fast lines, enough to support a solid 18 TPH if a flyover were inserted into the station approach. Then you could have up to 16 TPH semi-fast services from Didcot/Newbury/Reading stopping at the outer stations, as well as any potential Heathrow express services.

I'd give the lizzie line a timetable of 8 TPH each of Langley-Shenfield, Langley-Abbey Wood, and Heathrow-Abbey Wood.

Surely a couple of underrgound stations would be cheaper and more suitable than a brand new express tunnel extending much further, especially when we already have a perfectly functioning fast line between Paddington and Reading? We need to segregate the stoppers out from the semi-fasts and the freight services, so we can move the last semi-fasts off the main lines entirely.

Your forgetting that the most expensive part of building an underground railway is building the underground stations. It definitely believe it would be cheaper to build a tunnel from Old Oak Common to somewhere south of Heathrow and then an above surface high speed railway to Reading. By moving all the fast trains away from the GWML it gives us the flexibillity to provide additional services to the local stations like what you're trying to achieve with the Elizabeth Line tunnel, direct trains to Heathrow from the West of England/South Wales which will help combat congestion on the M4 and M25 and additional GWR/Elizabeth Line semi fasts + freight could run on the existing mainline with maybe perhaps a straight fast train from Paddington/OOC to Windsor?

 

[Bald Rick]

Yes but you're not necessarily putting the freight trains through the tunnel are you?

== Doublepost prevention - post automatically merged: 14 Sep 2026 ==

I don't think you're giving enough weight to the idea of putting the Elizabeth line in a tunnel with underground stations. Tunnel from OOC to east of Southall, 6-track from Southall to west of Langley. Extend to Slough if you're willing to do disruptive work in Slough town centre.

It would be able to support 24 TPH west of OOC, potentially split between OOC and Langley. Outer semi-fast commuter services could go non-stop from Slough to Old Oak Common, and terminate at Paddington with 2-3 platforms - leaving 9-10 platforms for the two fast lines, enough to support a solid 18 TPH if a flyover were inserted into the station approach. Then you could have up to 16 TPH semi-fast services from Didcot/Newbury/Reading stopping at the outer stations, as well as any potential Heathrow express services.

I'd give the lizzie line a timetable of 8 TPH each of Langley-Shenfield, Langley-Abbey Wood, and Heathrow-Abbey Wood.

Surely a couple of underrgound stations would be cheaper and more suitable than a brand new express tunnel extending much further, especially when we already have a perfectly functioning fast line between Paddington and Reading? We need to segregate the stoppers out from the semi-fasts and the freight services, so we can move the last semi-fasts off the main lines entirely.

Underground Elizabeth Line stations will be in the region of £1bn each over and above tunnelling costs.

 

[HSTEd]

I suspect an underground aggregate unloading system would be substantially cheaper than a passenger station. A loop in the running tunnel, then use hopper wagons in a short "box" containing an Merry Go Round style unloading pit with an aggregate hoist. Either put the unloading track in the middle of a two running line station so the train can reverse back immediately, or put it on a loop on one side of a single track running tunnel (if twin bores) and run the trains round in Acton Yard (as some already do).

Stations, especially ones sized for Elizabeth line sized trains and loads, are rather sprawling affairs.

 

[squingo44]

Underground Elizabeth Line stations will be in the region of £1bn each over and above tunnelling costs.

I thought that the cheaper Elizabeth line stations clocked in at a fair bit under £1bn each? Surely further away from the centre of London it will be cheaper to construct even underground stations.

Also what's the comparative cost of OOC to Southall + stations + surface 6-tracking versus tunnelling all the way to Reading?

== Doublepost prevention - post automatically merged: 14 Sep 2026 ==

Your forgetting that the most expensive part of building an underground railway is building the underground stations. It definitely believe it would be cheaper to build a tunnel from Old Oak Common to somewhere south of Heathrow and then an above surface high speed railway to Reading. By moving all the fast trains away from the GWML it gives us the flexibillity to provide additional services to the local stations like what you're trying to achieve with the Elizabeth Line tunnel, direct trains to Heathrow from the West of England/South Wales which will help combat congestion on the M4 and M25 and additional GWR/Elizabeth Line semi fasts + freight could run on the existing mainline with maybe perhaps a straight fast train from Paddington/OOC to Windsor?

Windsor branch shouldn't get anything. Make it a frequent shuttle and provide a TUAG express service from Slough to OOC.

How will you get the Shenfield services west of OOC without segregating a line for EL services though?

Would a high speed tunnel from Paddington to Reading via Heathrow really be cheaper than a tunnel from OOC to Southall with a couple of underground stations?

 

[Bald Rick]

I thought that the cheaper Elizabeth line stations clocked in at a fair bit under £1bn each?

The mid point of construction was over a decade ago. (I stood on the platforms at Tottenham Court Road over 11 years ago). Inflation between then and whenever such a proposal would be ready for construction will be at least 100%.

Surely further away from the centre of London it will be cheaper to construct even underground stations.

Probably not. It would be a little cheaper to buy the property needed above ground (noting that TfL / NR already owned much of the land needed for the EL, which is unlikely to be the case in the ‘burbs). However there is a lot of gravel in the geology in West london (hence all the aggregates terminals by the GWML) and that is far harder to tunnel through compared to London clay. Especially for big underground caverns.

 

[squingo44]

Probably not. It would be a little cheaper to buy the property needed above ground (noting that TfL / NR already owned much of the land needed for the EL, which is unlikely to be the case in the ‘burbs). However there is a lot of gravel in the geology in West london (hence all the aggregates terminals by the GWML) and that is far harder to tunnel through compared to London clay. Especially for big underground caverns.

So the cheapest option would be a no-stations tunnel of minimal length? What would that outcome look like?

 

[Mgameing123]

I thought that the cheaper Elizabeth line stations clocked in at a fair bit under £1bn each? Surely further away from the centre of London it will be cheaper to construct even underground stations.

Also what's the comparative cost of OOC to Southall + stations + surface 6-tracking versus tunnelling all the way to Reading?

== Doublepost prevention - post automatically merged: 14 Sep 2026 ==


Windsor branch shouldn't get anything. Make it a frequent shuttle and provide a TUAG express service from Slough to OOC.

How will you get the Shenfield services west of OOC without segregating a line for EL services though?

Would a high speed tunnel from Paddington to Reading via Heathrow really be cheaper than a tunnel from OOC to Southall with a couple of underground stations?

The idea is that by building a new high speed tunnel, the relief lines would be only used by Elizabeth Line services and whatever traffic is booted of the relief lines can go on the main line. Windsor would definitely be able to get a direct train to Paddington again if this were to happen as there should be the capacity for it. With your suggestion we aren't providing new links so even if it's a little cheaper by making the Elizabeth Line go underground it won't create as big of an economic impact as a direct airport connection to many cities in West England & South Wales.

 

[SynthD]

I suspect an underground aggregate unloading system would be substantially cheaper than a passenger station.

On a brand new line I can see this. But Acton Yard wouldn’t want the disruption, look at how the dive under was scheduled over Christmas and fast, to keep them operating.

So the cheapest option would be a no-stations tunnel of minimal length? What would that outcome look like?

Fast Elizabeth line on the mains with freight, stopper on the relief, GWR in the tunnels. All passenger trains stop at all platforms they pass (possibly except Southall, Iver, etc?). This would mean a more frequent but slightly slower single service to Heathrow.

Windsor would definitely be able to get a direct train to Paddington again if this were to happen as there should be the capacity for it.

I don’t think so, they’re still short trains. But there could be many more fast Elizabeth line trains to Slough, plus whatever GWR is doing this far out.

 

[NCT]

So the cheapest option would be a no-stations tunnel of minimal length? What would that outcome look like?

Supposing demand grows to the extent that metro, outer (first stop Slough) and long-distance need their dedicated tracks, a 'minimum viable product' would be a tunnel between Ladbrook Grove and (probably) Langley - somewhere you can put in a tunnel portal without knocking down houses. EL terminating at Slough, first-stop-Slough outers, WRLtH and freight would all need to be on the Reliefs at that points leaving room the tunnelled FL trains to join the old Mains. It'll be a tight squeeze but doable.

A more expansive solution would be for the fast line tunnel to emerge probably west of Maidenhead (the next available tunnel portal location without knocking down houses).

== Doublepost prevention - post automatically merged: 14 Sep 2026 ==

The idea is that by building a new high speed tunnel, the relief lines would be only used by Elizabeth Line services and whatever traffic is booted of the relief lines can go on the main line. Windsor would definitely be able to get a direct train to Paddington again if this were to happen as there should be the capacity for it. With your suggestion we aren't providing new links so even if it's a little cheaper by making the Elizabeth Line go underground it won't create as big of an economic impact as a direct airport connection to many cities in West England & South Wales.

Hmmm, I hadn't considered that if the new fast tunnels emerged west of Slough the outer suburbans could remain on the Mains through Slough. In which case yes direct to Windsor does become a possibility ...

 

[squingo44]

Slough is probably too difficult to widen. There's a lot more space for Langley to expand and form the terminus of the stopping services, and the first stop of the outer suburbans. You could have 8 TPH each Shenfield-Langley, Abbey Wood-Langley, and Abbey Wood-Heathrow. No need for express elizabeth line services whatsoever.

How would Acton Yard work if the freight services were removed from the relief lines?

 

[NCT]

Slough is probably too difficult to widen. There's a lot more space for Langley to expand and form the terminus of the stopping services, and the first stop of the outer suburbans. You could have 8 TPH each Shenfield-Langley, Abbey Wood-Langley, and Abbey Wood-Heathrow. No need for express elizabeth line services whatsoever.

How would Acton Yard work if the freight services were removed from the relief lines?

You don't need all 24tph west of Paddington. OOC starters are useful for soaking HS2 loads. Freight stays on the reliefs.

 

[Bald Rick]

So the cheapest option would be a no-stations tunnel of minimal length? What would that outcome look like?

No idea!

 

[ChiefPlanner]

I seem to recall that the old GWR planned on 6 tracking from Acton Yard to Slough as far back as the 1910 era.......of course that option has long dissapeared (along with slow coal trains with best Welsh coal heading for that there London , which was probably the reasoning behind their ideas) - maybe someone can go to Kew and have a delve in the archives wihout getting distracted in the wealth of material they have there !)

 

[HSTEd]

On a brand new line I can see this. But Acton Yard wouldn’t want the disruption, look at how the dive under was scheduled over Christmas and fast, to keep them operating.

Well I'm not sure the disruption would be much different for either option.
I think any tunnel option would have to start in the vicinity of Acton yard regardless because there isn't much better of a location between there and the platforms at Old Oak Common.

It just depends what lines the tunnel comes up to connect to. The MGR discharge building at Drax is only ~50m long, so assuming that a box for an underground one would be of a similar size it is pretty compact compared to the size of pretty much any of the aggregate terminals between Acton and Slough.

 

[Mgameing123]

On a brand new line I can see this. But Acton Yard wouldn’t want the disruption, look at how the dive under was scheduled over Christmas and fast, to keep them operating.

Fast Elizabeth line on the mains with freight, stopper on the relief, GWR in the tunnels. All passenger trains stop at all platforms they pass (possibly except Southall, Iver, etc?). This would mean a more frequent but slightly slower single service to Heathrow.

I don’t think so, they’re still short trains. But there could be many more fast Elizabeth line trains to Slough, plus whatever GWR is doing this far out.

We can always extend the platforms if neccesary.