Should the HS2-HS1 tunnel under London be uncancelled?

[Bald Rick]

I think this is now at the stage of being the most unrealisitic crayoned proposal we have ever seen on this forum, with a proposer who is the most allergic to challenge. And that is in a wide field of entries.

I have prepared an initial top 10 of questions that need answering.

But we aren't talking about today's track or signalling.

But you said in one of your first posts (my bold):

1) The existing viaduct around Camden market is already 8.4m wide so it’s wide enough for a pair of GC gauge tracks. The work is just to replace bridge superstructures @ about £8 million each for 6 bridges ( Whaley bridge just got new superstructure for £5.1m ).

So forgive me if I thought you were talking about today’s track and signalling.

It is, however, 40kph from the St Pancras bufferstops to the Camden Silo Curve. If a higher speed was possible, it would have been provided for when St Pancras was rebuilt, so we have to assume it is not possible. However, to get access to the domestic platforms as you propose does require the complete remodelling of the St Pancras throat.

Q1: What is your cost allowance for the complete replacement of all the track, signalling, overhead line and other assets in the St Pancras approaches? Include the compensation to Eurostar and Southeastern for loss of revenue.


As you now appear to be a track designer (or do I have that wrong?) you will have worked out what the cant and cant deficiency is on your rebuilt NLL and connections that allows this higher speed taking into account the maximum limits through S&C.

Q2: What cost allowance have you made for the complete rebuilding of track, signalling, overhead line and structures between the Silo curve and Primrose Hill, including a new station for Camden Road, and continued provision for freight to operate via Primrose Hill?

Q3: What are the results of the assessments you have made of the 80+ different technical and operational factors that have to be conducted when investigating the raising of linespeed? Horizontal alignment is just one of them.

Q4: What is your proposed solution if (when) it turns out that the previous studies (done by teams of professional engineers) that concluded rebuilding both the NLL tracks for GC gauge was impractical, is correct, and you can’t do the work without completely rebuilding the whole viaduct? What cost allowance have you made for this risk?


I’m very pleased to see you have accepted that there are 7tph Southeastern high speed services in the peak, albeit it took a couple of hundred posts and nearly two weeks, when a quick glance at the timetable on your phone would have taken you 30 seconds, and saved us all a lot of time. Your proposed solution of sending more HS2 trains to Ashford by turning more of them at St Pancras - potentially at 6 minute intervals - will simply not work reliably. The shortest regular repeated multi platform terminus turnrounds with 200m+ trains anywhere in this country are at 12 minute intervals, and that is with high density rolling stock on a commuter railway. Also sending the peak extras to Ashford is not enough - these peak extras are from and to places like Broadstairs, Faversham, Sandwich, Dover and Maidstone West.

Q5: On what basis have you decided that a repeated 7.5 minute (or 6 minute) departure to departure turnround is in any way practical or physically possible for 200m / 400m high speed rolling stock with intercity door arrangements and long distance passengers potentially with luggage etc? Note how long it takes any long distance train at Euston or Kings Cross to be empty of passengers from the moment it receives a proceed aspect on the home signal, and how long it takes to reload, depart, and then clear the fouling point for the platfrom line on departure. (I have studied this, at length, several times during my career).


You say “you see no demolition necessary…” apart from the top floor of a dentists. All previous studies have shown the need for land take and local disruption. Every other railway project of this nature that I can think of in an urban area has done so. Some of it will be permanent, some will be temporary - you simply can not rebuild a line through the middle of a busy urban area without having site compounds, offices, storage areas, parking, generators, and all that goes with a massive building site. In particular for this proposal, you have two TBMs to extract and you also propose to build a viaduct right through the middle of one of North London’s most important ready mixed concrete sites - one that is rail connected. (Indeed one that supplied the concrete that rebuilt much of St Pancras itself, and would be expected to supply the concrete for your proposal, except it can’t).

Q6: What cost allowance have you made for gaining the necessary consents to build and operate the new lines, including the legal processes, land purchase, and compensation to nearby affected property owners, businesses and residents who will be affected by the work and the end result?


Despite it being pointed out to you, repeatedly, that you cannot currently turn trains at Stratford International to/from the West, you keep suggesting it.

Q7: What is your proposed solution for turning trains at Stratford to/from the west, and what cost allowance have you made for this work to be done? If such an engineering solution is not reasonably practical, where do you intend to send the trains and what work is necessary for that to happen?

Q8: What is your proposed solution for the signalling of Javelin services on HS2, and HS2 services into St Pancras and onto HS1, and what cost allowance have you made for this? Currently, it is three different signalling systems (HS2 is ETCS L2 with ATO, HS1 from the London tunnels eastwards is TVM430, St Pancras area is KVB.)

Q9: What conclusion have you reached when assessing the capacity of the power supply on HS1 to accommodate the extended HS2 services, in particular the capacity of the local distribution around St Pancras to accommodate trains arriving and departing every minute or so. What cost allowance have you made for this?


Finally, you are suggesting sending internatonal services to OOC, and Javelins to Heathrow. The only practical solution to link HS2 to Heathrow would be to significantly expand the already finished Victoria Road crossover box, and bore tunnels from there to somewhere on the GWML in the Ealing area.

Q10: What cost allowances have you made for
a) the link between OOC and the GWML
b) extending the platforms at Heathrow to accept trains longer than 190 metres
c) Providing international border control and security at OOC.


That will do for now. I look forward to the answers.

 

[Class15]

Q2: What cost allowance have you made for the complete rebuilding of track, signalling, overhead line and structures between the Silo curve and Primrose Hill, including a new station for Camden Road, and continued provision for freight to operate via Primrose Hill?

Most of the points you have made are very fair and I personally don’t think that the idea being discussed here is realistic, but this Primrose Hill freight point is really puzzling me. Just a few weeks ago the space in the timetable between Gospel Oak and Kensal Green was found to add a whole load of paths to London Gateway. Therefore, it begs the question, why can’t the same be done for the remaining Felixstowe trains. Freight going via Primrose Hill will also be significantly reduced (and already is, 5 return Felixstowe - WCML services have either stopped or are stopping next week), leaving just a couple in the daytime hours.

 

[Harpo]

How is it ‘misinformation’ to simply suggest that extending the Elizabeth line to Ebsfleet would be cheaper. Do you have some costings to back that up?

Good luck @Bald Rick. Hopefully there’ll be something more substantial on Q1-10 than the Trumpian dismissal that I got.

 

[The Planner]

Most of the points you have made are very fair and I personally don’t think that the idea being discussed here is realistic, but this Primrose Hill freight point is really puzzling me. Just a few weeks ago the space in the timetable between Gospel Oak and Kensal Green was found to add a whole load of paths to London Gateway. Therefore, it begs the question, why can’t the same be done for the remaining Felixstowe trains. Freight going via Primrose Hill will also be significantly reduced (and already is, 5 return Felixstowe - WCML services have either stopped or are stopping next week), leaving just a couple in the daytime hours.

Don't look at it as what is running, look at it as paths/capacity.

 

[Bald Rick]

Most of the points you have made are very fair and I personally don’t think that the idea being discussed here is realistic, but this Primrose Hill freight point is really puzzling me. Just a few weeks ago the space in the timetable between Gospel Oak and Kensal Green was found to add a whole load of paths to London Gateway. Therefore, it begs the question, why can’t the same be done for the remaining Felixstowe trains. Freight going via Primrose Hill will also be significantly reduced (and already is, 5 return Felixstowe - WCML services have either stopped or are stopping next week), leaving just a couple in the daytime hours.

But here’s the thing. There is currently an almighty scrap going on behind the scenes because there *aren’t* the paths for everything out of Gateway. And the Felixstowe paths look like they are going to be refilled.

Don’t forget the diverted path has to work at Gospel Oak, Willesden, and then on to wherever it is going (and vice versa). If the eastbound is just a couple of minutes out at Stratford, it misses it’s slot on the GEML and therefore no path. Also the route is used for ECS at start and rhe end of the day, what happens to that?

 

[Class15]

But here’s the thing. There is currently an almighty scrap going on behind the scenes because there *aren’t* the paths for everything out of Gateway. And the Felixstowe paths look like they are going to be refilled.

Are they though? A lot of the Felixstowe trains don’t run anymore. Would you expect them to come back quickly? If so, great.

Don’t forget the diverted path has to work at Gospel Oak, Willesden, and then on to wherever it is going (and vice versa). If the eastbound is just a couple of minutes out at Stratford, it misses its slot on the GEML and therefore no path. Also the route is used for ECS at start and rhe end of the day, what happens to that?

As long as you’re in the same overground gap you can make the same path at Stratford, for example with my 4L89 example. ECS is maybe more challenging, where is it coming from? If Willesden depot then I guess it can run via Willesden Low Level and Gospel Oak?

 

[zwk500]

As long as you’re in the same overground gap you can make the same path at Stratford

The headways published by NR demonstrate it's not as simple as that. The headway following a stopping overground train at Hamstead Heath goes out to 5 minutes, and the headway following a freight is 4 minutes, so a 2nd LO following a freight following an LO would need to be 9 minutes apart, but to fit 8tph LO through you need the services to be 7.5 mins on average. So to recover the service you'll need 2 successive LO trains at 6 mins apart which doesn't leave room for the freight between them.
However, the headways from Stratford to Camden Town are 3 following a LO and a mix of 3 and 4 following freight, meaning you can have LO and Freight alternate at a consistent 7 minute interval if you needed to. If all of that freight went via Hampstead Heath, the knock-on effect of the 9 minutes required at Hamsptead Heath would multiply quickly across all the freight. *That's* why you need Primrose Hill.

 

[Class15]

The headways published by NR demonstrate it's not as simple as that. The headway following a stopping overground train at Hamstead Heath goes out to 5 minutes, and the headway following a freight is 4 minutes, so a 2nd LO following a freight following an LO would need to be 9 minutes apart, but to fit 8tph LO through you need the services to be 7.5 mins on average. So to recover the service you'll need 2 successive LO trains at 6 mins apart which doesn't leave room for the freight between them.
However, the headways from Stratford to Camden Town are 3 following a LO and a mix of 3 and 4 following freight, meaning you can have LO and Freight alternate at a consistent 7 minute interval if you needed to. If all of that freight went via Hampstead Heath, the knock-on effect of the 9 minutes required at Hamsptead Heath would multiply quickly across all the freight. *That's* why you need Primrose Hill.

Thanks. I wonder why the headway is so much larger on the Hampstead Heath section. Could it be reduced by adding a couple of extra signals, for example between Finchley Road and West Hampstead?

 

[zwk500]

ECS is maybe more challenging, where is it coming from? If Willesden depot then I guess it can run via Willesden Low Level and Gospel Oak?

Requiring the extra runtime involved in reversing in the Bay at Willesden Jn WL, the extra conflict at the flat jn and the extra runtime via Hampstead...

Thanks. I wonder why the headway is so much larger on the Hampstead Heath section. Could it be reduced by adding a couple of extra signals, for example between Finchley Road and West Hampstead?

My bet is Hamspstead Heath tunnel, which is basically the entire distance between those two stations, already has signals in the tunnel, and quite possibly has restrictions on sending more than 2 trains into the tunnel at once for safety/evacuation reasons. Gradients may also be playing a factor in acceleration times at that location as well, although I'd need to check a few more documents to get an idea how important that is.

Worth noting those headways are from the 2026 V2 rules (applicable to Dec25 timetable), and are changed from when I was timing the North London Line for NR (when they were a bit more granular, pre-covid) and I haven't gone back to see when they changed.

 

[Bald Rick]

Are they though? A lot of the Felixstowe trains don’t run anymore. Would you expect them to come back quickly?

Yes. There was suppressed demand, which is now being freed.

ECS is maybe more challenging, where is it coming from?

Euston, Kilburn loop, Willesden and Wembley.

My bet is Hamspstead Heath tunnel

Bet won!

 

[Class15]

Yes. There was suppressed demand, which is now being freed.

Okay, many thanks, so 4M88, 4L89 and the like will come back at some point?

Euston, Kilburn loop, Willesden and Wembley.

Willesden and Wembley are easy to reroute, I accept that Euston is a challenge. Does stock really berth overnight at Kilburn loop? I was under the impression it was a goods loop.

Bet won!

That makes sense (I assume that is the same as Hampstead Tunnel, which is the name I always heard). Could any upgrades in the tunnel improve things?

 

[zwk500]

Willesden and Wembley are easy to reroute, I accept that Euston is a challenge. Does stock really berth overnight at Kilburn loop? I was under the impression it was a goods loop.

Stock uses it to reverse back having come from Camden to Euston or vice versa, to save the time and conflicts of having to go to Willesden.

That makes sense (I assume that is the same as Hampstead Tunnel, which is the name I always heard). Could any upgrades in the tunnel improve things?

No "quick fixes", for the reasons given above. Any serious improvement is likely to need to wait until ETCS L2, and even then the interaction of metro and heavy freight is still a 'laws of physics' problem as much as a signalling design issue.

 

[Class15]

Stock uses it to reverse back having come from Camden to Euston or vice versa, to save the time and conflicts of having to go to Willesden.

No "quick fixes", for the reasons given above. Any serious improvement is likely to need to wait until ETCS L2, and even then the interaction of metro and heavy freight is still a 'laws of physics' problem as much as a signalling design issue.

Thanks. Guess Primrose Hill will still be needed for a while longer in that case.

 

[Bald Rick]

Okay, many thanks, so 4M88, 4L89 and the like will come back at some point?

Something in similar paths, yes.

Willesden and Wembley are easy to reroute

Not necessarily.

Does stock really berth overnight at Kilburn loop?

Realtime Trains | 5N57 0555 Kilburn Up & Down Gds Lp to Stratford (London) | 28/03/2025

Real-time train running information for 5N57 0555 departure from Kilburn Up & Down Gds Lp to Stratford (London) on 28/03/2025. From Realtime Trains, an independent source of train running info for Great Britain.

www.realtimetrains.co.uk

 

[Class15]

Something in similar paths, yes.

Thanks.

Not necessarily.

In what ways exactly? Wembley C sidings for example should have direct access to the City Goods lines at Harlesden Jn.

Realtime Trains | 5N57 0555 Kilburn Up & Down Gds Lp to Stratford (London) | 28/03/2025

Real-time train running information for 5N57 0555 departure from Kilburn Up & Down Gds Lp to Stratford (London) on 28/03/2025. From Realtime Trains, an independent source of train running info for Great Britain.

www.realtimetrains.co.uk

That particular one seems to split off 5N98 at Kilburn loop.

 

[Bald Rick]

In what ways exactly? Wembley C sidings for example should have direct access to the City Goods lines at Harlesden Jn.

Not if they, or the NLL to Gospel Oak are closed!

 

[John Jefkins]

I think this is now at the stage of being the most unrealisitic crayoned proposal we have ever seen on this forum, with a proposer who is the most allergic to challenge. And that is in a wide field of entries.

I have prepared an initial top 10 of questions that need answering.




But you said in one of your first posts (my bold):




So forgive me if I thought you were talking about today’s track and signalling.

It is, however, 40kph from the St Pancras bufferstops to the Camden Silo Curve. If a higher speed was possible, it would have been provided for when St Pancras was rebuilt, so we have to assume it is not possible. However, to get access to the domestic platforms as you propose does require the complete remodelling of the St Pancras throat.

Q1: What is your cost allowance for the complete replacement of all the track, signalling, overhead line and other assets in the St Pancras approaches? Include the compensation to Eurostar and Southeastern for loss of revenue.


As you now appear to be a track designer (or do I have that wrong?) you will have worked out what the cant and cant deficiency is on your rebuilt NLL and connections that allows this higher speed taking into account the maximum limits through S&C.

Q2: What cost allowance have you made for the complete rebuilding of track, signalling, overhead line and structures between the Silo curve and Primrose Hill, including a new station for Camden Road, and continued provision for freight to operate via Primrose Hill?

Q3: What are the results of the assessments you have made of the 80+ different technical and operational factors that have to be conducted when investigating the raising of linespeed? Horizontal alignment is just one of them.

Q4: What is your proposed solution if (when) it turns out that the previous studies (done by teams of professional engineers) that concluded rebuilding both the NLL tracks for GC gauge was impractical, is correct, and you can’t do the work without completely rebuilding the whole viaduct? What cost allowance have you made for this risk?


I’m very pleased to see you have accepted that there are 7tph Southeastern high speed services in the peak, albeit it took a couple of hundred posts and nearly two weeks, when a quick glance at the timetable on your phone would have taken you 30 seconds, and saved us all a lot of time. Your proposed solution of sending more HS2 trains to Ashford by turning more of them at St Pancras - potentially at 6 minute intervals - will simply not work reliably. The shortest regular repeated multi platform terminus turnrounds with 200m+ trains anywhere in this country are at 12 minute intervals, and that is with high density rolling stock on a commuter railway. Also sending the peak extras to Ashford is not enough - these peak extras are from and to places like Broadstairs, Faversham, Sandwich, Dover and Maidstone West.

Q5: On what basis have you decided that a repeated 7.5 minute (or 6 minute) departure to departure turnround is in any way practical or physically possible for 200m / 400m high speed rolling stock with intercity door arrangements and long distance passengers potentially with luggage etc? Note how long it takes any long distance train at Euston or Kings Cross to be empty of passengers from the moment it receives a proceed aspect on the home signal, and how long it takes to reload, depart, and then clear the fouling point for the platfrom line on departure. (I have studied this, at length, several times during my career).


You say “you see no demolition necessary…” apart from the top floor of a dentists. All previous studies have shown the need for land take and local disruption. Every other railway project of this nature that I can think of in an urban area has done so. Some of it will be permanent, some will be temporary - you simply can not rebuild a line through the middle of a busy urban area without having site compounds, offices, storage areas, parking, generators, and all that goes with a massive building site. In particular for this proposal, you have two TBMs to extract and you also propose to build a viaduct right through the middle of one of North London’s most important ready mixed concrete sites - one that is rail connected. (Indeed one that supplied the concrete that rebuilt much of St Pancras itself, and would be expected to supply the concrete for your proposal, except it can’t).

Q6: What cost allowance have you made for gaining the necessary consents to build and operate the new lines, including the legal processes, land purchase, and compensation to nearby affected property owners, businesses and residents who will be affected by the work and the end result?


Despite it being pointed out to you, repeatedly, that you cannot currently turn trains at Stratford International to/from the West, you keep suggesting it.

Q7: What is your proposed solution for turning trains at Stratford to/from the west, and what cost allowance have you made for this work to be done? If such an engineering solution is not reasonably practical, where do you intend to send the trains and what work is necessary for that to happen?

Q8: What is your proposed solution for the signalling of Javelin services on HS2, and HS2 services into St Pancras and onto HS1, and what cost allowance have you made for this? Currently, it is three different signalling systems (HS2 is ETCS L2 with ATO, HS1 from the London tunnels eastwards is TVM430, St Pancras area is KVB.)

Q9: What conclusion have you reached when assessing the capacity of the power supply on HS1 to accommodate the extended HS2 services, in particular the capacity of the local distribution around St Pancras to accommodate trains arriving and departing every minute or so. What cost allowance have you made for this?


Finally, you are suggesting sending internatonal services to OOC, and Javelins to Heathrow. The only practical solution to link HS2 to Heathrow would be to significantly expand the already finished Victoria Road crossover box, and bore tunnels from there to somewhere on the GWML in the Ealing area.

Q10: What cost allowances have you made for
a) the link between OOC and the GWML
b) extending the platforms at Heathrow to accept trains longer than 190 metres
c) Providing international border control and security at OOC.


That will do for now. I look forward to the answers.

Q1: What is your cost allowance for the complete replacement of all the track, signalling, overhead line and other assets in the St Pancras approaches? Include the compensation to Eurostar and Southeastern for loss of revenue.

As your track layout pointed out, almost all the work is either side of the existing St Pancras approaches (my revised plan to follow - as I agree that a longer cross-over viaduct is needed to reach a 200m ramp on the Camden Boatyard side). What I am proposing is to widen the NLL approach (without interrupting St Pancras, build a viaduct over the top (columns between tracks, but no track changes apart from the addition of the extra cross-over routes you proposed) and then build a ramp down over the boat dock.
Those new tracks would then need connection work, but no "complete replacement" and "no other assets changed",

Why would signalling need to change on the existing tracks? As you said, St Pancras has 3 existing roads, so just one of them (for one side) would be taken out at a time.
As HS1 would be benefitting from a vast increase in use, we've got at least 5 years to do this in and some trackwork would be needed for maintenance anyway, its not terrible.
Methinks you protest too much here

As you now appear to be a track designer (or do I have that wrong?) you will have worked out what the cant and cant deficiency is on your rebuilt NLL and connections that allows this higher speed taking into account the maximum limits through S&C.
I'm just pointing out that straight track and 350 metre radius curves don't normally get limited to 15 mph. A better estimate is 35 to 45 mph - say 65 kph average.
You are the expert. I'm just saying we need to get real here.
There isn't the money to build 11 platforms at Euston - so this a more pragmatic solution that's billions cheaper, easier to open earlier & boost revenue.
Let's solve the issues by being constructive here. I am on the side of progress. I want a solution that our Government can afford please.

Q2: What cost allowance have you made for the complete rebuilding of track, signalling, overhead line and structures between the Silo curve and Primrose Hill, including a new station for Camden Road, and continued provision for freight to operate via Primrose Hill?

As Arup's drawings showed, they relaid tracks on the existing viaduct whilst replacing the bridges.
Track replacement costs are about £150,000 / km - eg £400,000 for these two tracks. Signalling perhaps another £1 million - but we're replacing the route into Euston though.
I just rounded the bridge superstructure costs (of £8m x 6) by £5m and rounded it up to £60m to £70 million. Ten times cheaper than £600m of tunnel to Euston.
If we add the St Pancras stuff up to say £120m we might get £200 to £250 million. All rather cheaper than £6 BILLION. And with private HS1 money funding a lot of it.

Q3: What are the results of the assessments you have made of the 80+ different technical and operational factors that have to be conducted when investigating the raising of linespeed? Horizontal alignment is just one of them.
When TfL trains are not limited to 15 mph, why are you saying that these trains cannot run at around 40 mph? This isn't rocket science. Other trains run this route at 40mph.
The curves at each end are around radii of 350 metres which most rail lines limit to around 40mph (eg 60 km/hr). You are splitting hairs here. Be fair.
(Or are you one of the people with a vested interest in wasting taxpayers money on a £6 billion Euston?)
I'm just trying to ensure that HS2 actually gets built into London! Right now that is at risk due to HS2 costs rising way too high.
Q4: What is your proposed solution if (when) it turns out that the previous studies (done by teams of professional engineers) that concluded rebuilding both the NLL tracks for GC gauge was impractical, is correct, and you can’t do the work without completely rebuilding the whole viaduct? What cost allowance have you made for this risk?
Arup's drawings clearly state that they are using the existing viaduct but relaying tracks and replacing steelwork over the bridges. Look at that drawing.
I didn't edit their text that talks about "skewing tracks for GC guage". And I've checked their measurements with a Disto to prove the viaduct is 8.4m wide.
Their professional engineers produced those drawings. TfL use the same viaduct. So do heavy freight trains. Why do you want to rebuild it?

As for train turnaround times, look at TfL trains which turn in 2 minutes. These are only 200 metre long classic trains where the driver needs 2 minutes to walk to the end.
And about 1/3rd of passengers wouldn't be getting off them. These are through trains reversing. At rush hour we could even use stepping back (with a driver waiting at the end).
I have allowed for 5 minute turnarounds within 7.5 minute slots - ie exactly what Frankfurt HbH does with ICE trains. But I suggest that for most trains 4 minutes is enough.
It's about time we copied best practice from either Frankfurt or Tokyo instead of having a can't do attitude.

Look at where those Javelins go. Two per hour at rush hour really do only go to Ashford. But I gave 3 ways to solve the 7 trains/hr issue.
I like temporary use of platform 10 best, with that combined with sending some Birmingham trains (normally turning in a double slot at St Pancras but extended to Ashford in rush hour to postpone their use of the return slot until after rush hour). That combination adds an extra 15 slots of 7.5 minutes each over say 90 minutes. Room for expansion!

Q5: On what basis have you decided that a repeated 7.5 minute (or 6 minute) departure to departure turnround is in any way practical or physically possible for 200m / 400m high speed rolling stock with intercity door arrangements and long distance passengers potentially with luggage etc? Note how long it takes any long distance train at Euston or Kings Cross to be empty of passengers from the moment it receives a proceed aspect on the home signal, and how long it takes to reload, depart, and then clear the fouling point for the platfrom line on departure. (I have studied this, at length, several times during my career).

On the basis that I have video evidence of Bullet trains being terminated and turned in Tokyo and have used Frankfurt HbH many times and studied the timetable.
I have timed people getting off Eurostar trains with luggage. I have seen High Speed trains arrive and depart in those times elsewhere.
And on the basis that Metro trains do this in this country all of the time. Why is 7.5 minutes too short a time to just reverse a 200 metre long train? (none are 400m ones).
400m trains are another subject for the "Eurostar" platforms when HS1 gets their deal with Virgin or whoever sorted out. Not for now.

Q6: What cost allowance have you made for gaining the necessary consents to build and operate the new lines, including the legal processes, land purchase, and compensation to nearby affected property owners, businesses and residents who will be affected by the work and the end result?

This is an "upgrade of an existing railway" - so the bridges only need Camden Council's planning permission. Network Rail is allowed to upgrade existing railways with only local planning permissions.
Railway Land north of Juniper Crescent is within the HS2 Limit of Deviation too.

I keep telling you that only one property needs any land purchase. As this is an existing railway, these electric trains would make less noise than diesel freight trains. What "compensation" when residents chose to live by this existing railway?
And yet again, what "land purchase"? Stop repeating misinformation.
There is only one property affected. Camden Market is unaffected.
Road traffic would be the main concern for the 6 week periods needed to replace bridge superstructures (eg Whalley Bridge took that long for £5.1m). That (and the design of road bridges) would be Camden Council's main concern.
We are also after all now going to "fast track planning" in order to boost growth.

This project does exactly that - as it provides platforms for less money and boosts passenger demand by providing far better interchanges than a Euston dead end.

Q7: What is your proposed solution for turning trains at Stratford to/from the west, and what cost allowance have you made for this work to be done? If such an engineering solution is not reasonably practical, where do you intend to send the trains and what work is necessary for that to happen?
Despite it being pointed out to you, repeatedly, that you cannot currently turn trains at Stratford International to/from the West, you keep suggesting it.

Look at the west end of the route up to Temple Mills depot. Those same tracks just need to X connect across to tracks to central platforms either side. An easy change.
So it IS INDEED possible to terminate trains on the central platforms of Stratford. Over the weekend, I could draw it for you - but I'm sure you can see what I mean.
These 200m long terminating trains would then use the central platforms. Through trains would use the outer platforms.
Nothing would then cross the fast lines in the wrong direction. I agree that Ebbsfleet is easier to use for 400m train terminations as platforms are all between the fast lines.

Q8: What is your proposed solution for the signalling of Javelin services on HS2, and HS2 services into St Pancras and onto HS1, and what cost allowance have you made for this? Currently, it is three different signalling systems (HS2 is ETCS L2 with ATO, HS1 from the London tunnels eastwards is TVM430, St Pancras area is KVB.)

Again, I don't claim expertise except to say its up to you to solve it - without that costing £6 billion. If you can't, then we risk not getting HS2 into London.
Stop finding obstacles and start finding solutions. It is crazy to have incompatible signaling solutions and HS1 have already said they want better compatibility with ETCS.
HS1 are thus already in the process of changing to ETCS according to recent publicity. Let them get on with that and let's make sure Javelins get the kit.
Check this link which shows that HS1 are indeed already upgrading to ETCS - https://www.railengineer.co.uk/upgrading-the-continental-connection/

Q9: What conclusion have you reached when assessing the capacity of the power supply on HS1 to accommodate the extended HS2 services, in particular the capacity of the local distribution around St Pancras to accommodate trains arriving and departing every minute or so. What cost allowance have you made for this?
Again, there is a simple answer to this. That's for HS1 to fund. They would after all be benefitting by a huge boost in track and platform access fees. The government could long rent out HS1 for many more billions every time they do so. This all boosts demand on both HS1 and HS2 - so money can be found to add a little extra power supply.
Its a lot cheaper than £6 billion.

Finally, you are suggesting sending internatonal services to OOC, and Javelins to Heathrow. The only practical solution to link HS2 to Heathrow would be to significantly expand the already finished Victoria Road crossover box, and bore tunnels from there to somewhere on the GWML in the Ealing area.

I have suggested 2 options.

Option 1 is to send 4 Javelins/hr (maybe more at rush hour) to terminate at OOC and 8 Classic compatible 200m HS2 trains/hr to terminate along all of the HS1 platforms (with most reversing within 7.5 minute slots at St Pancras.


Option 2 is to extend those Javelins to Heathrow or to Woking (via a ramp S curving through the OOC box - just like the ramp through Stratford Internation to Temple Mills) and free up the central platforms at OOC to receive some Eurostar trains.
An S curve reversable single track ramp through the station box to OOC GWR platforms doesn't need new tunnels (except for a short cut & cover at the top).
It almost all fits within the station box.




I agree that Option 2 involves border control facilities in OOC - (some glass screens and offices). It costs about £100m more. But it repays those costs annually from 2040.
By freeing up Paddington platforms for more GWR trains, by re-using the existing 4 slots to Heathrow from the Heathrow express and by boosting cross London passengers with lucrative fares from St Pancras or Stratford or Ashford to Heathrow it boosts revenue.
If the Staines link is built, those same trains could run to Woking and link the South Western network to Heathrow, OOC and St Pancras too.
The extra revenue coming from connecting all of these rail networks together would surely fund a short platform extension at Heathrow???

Good luck @Bald Rick. Hopefully there’ll be something more substantial on Q1-10 than the Trumpian dismissal that I got.

I'm just saying that the cost of reaching St Pancras and existing HS1 platforms is in the region of £250m with HS1 Ltd funding half of it (in return for track / platform access fees).
The cost of extending the Elizabeth Line to Ebbsfleet has been estimated north of £3 Billion - ie ten times more.
The Elizabeth line is already full. Its a metro (with no loos). Its not the same sexy alternative to cross London on express trains that only stop at Ebbsfleet, Stratford, St Pancras and OOC (plus possibly Heathrow and Woking with my "option 2").
But yes - Elizabeth line success proves the case for this type of ACROSS London link. (sorry caps again ...) We could be running up to 20 trains/hr between Stratford and OOC on this link. Mostly domestic, with some Eurostars too.

The key thing is to reduce the need of interchanges by running as many through alternatives as possible with cross-platform or near-platform changes (eg Thameslink to western Javelins or HS2 at St Pancras).

Finally, I accept that you are the experts here. I'm just saying that without this sort of re-think of where HS2 trains terminate, we risk nothing getting built at all.
Euston isn't funded. The Government only wants to put about 4 platforms there. Please let's work together instead of shooting me down in flames. I'm a retired Architect who has worked on railway projects.
I am after all just a volunteer here. Nobody is paying me to produce these ideas (or the retired commercial director who gave me the PDFH data). But I suspect some of you are being paid to shoot me down?
We've had a feeding frenzy of HS2 consultant fees? The UK has been made a laughing stock by multiplying HS2 costs to 10 times what anyone else pays?
And as I'm new to this site, (and was on holiday last week) it took a week for me to notice the tiny page number buttons. I thought my early replies were not getting posted. And I never saw your other questions.
As for being compared to Trump. No way. I really am trying to answer you. But, again, lets be constructive together here. Let's find a way to make this happen.

 

[SynthD]

St Pancras already has an upgraded tube station.

St Pancras has an upgraded tube station for the current use, and future growth. To add on additional use would use all that up and immediately need another upgrade.

What we need to do urgently is work out how to add an S shaped single tracked ramp within the O.O.C. box

That would end up too far north, heading for North Acton via a lot of living rooms.

Contracts are subject to change

Typically this doesn’t claw back all the money.

What I am proposing is to widen the NLL approach (without interrupting St Pancras, build a viaduct over the top (columns between tracks, but no track changes apart from the addition of the extra cross-over routes you proposed) and then build a ramp down over the boat dock.

What is supporting those columns?

Look at the west end of the route up to Temple Mills depot. Those same tracks just need to X connect across to tracks to central platforms either side. An easy change.
So it IS INDEED possible to terminate trains on the central platforms of Stratford. Over the weekend, I could draw it for you - but I'm sure you can see what I mean.

Please do, because I can’t see it. The route to temple mills is above the platforms 2 and 3.

The extra revenue coming from connecting all of these rail networks together would surely fund a short platform extension at Heathrow?

If the cost of that extension could be said out loud, that question could be answered.

I'm a retired Architect who has worked on railway projects.

Without wishing to demand your CV, what were those projects?

 

[yoyothehobo]

Q1: What is your cost allowance for the complete replacement of all the track, signalling, overhead line and other assets in the St Pancras approaches? Include the compensation to Eurostar and Southeastern for loss of revenue.

As your track layout pointed out, almost all the work is either side of the existing St Pancras approaches (my revised plan to follow - as I agree that a longer cross-over viaduct is needed to reach a 200m ramp on the Camden Boatyard side). What I am proposing is to widen the NLL approach (without interrupting St Pancras, build a viaduct over the top (columns between tracks, but no track changes apart from the addition of the extra cross-over routes you proposed) and then build a ramp down over the boat dock.
Those new tracks would then need connection work, but no "complete replacement" and "no other assets changed",

Why would signalling need to change on the existing tracks? As you said, St Pancras has 3 existing roads, so just one of them (for one side) would be taken out at a time.
As HS1 would be benefitting from a vast increase in use, we've got at least 5 years to do this in and some trackwork would be needed for maintenance anyway, its not terrible.
Methinks you protest too much here

As you now appear to be a track designer (or do I have that wrong?) you will have worked out what the cant and cant deficiency is on your rebuilt NLL and connections that allows this higher speed taking into account the maximum limits through S&C.
I'm just pointing out that straight track and 350 metre radius curves don't normally get limited to 15 mph. A better estimate is 35 to 45 mph - say 65 kph average.
You are the expert. I'm just saying we need to get real here.
There isn't the money to build 11 platforms at Euston - so this a more pragmatic solution that's billions cheaper, easier to open earlier & boost revenue.
Let's solve the issues by being constructive here. I am on the side of progress. I want a solution that our Government can afford please.

Q2: What cost allowance have you made for the complete rebuilding of track, signalling, overhead line and structures between the Silo curve and Primrose Hill, including a new station for Camden Road, and continued provision for freight to operate via Primrose Hill?

As Arup's drawings showed, they relaid tracks on the existing viaduct whilst replacing the bridges.
Track replacement costs are about £150,000 / km - eg £400,000 for these two tracks. Signalling perhaps another £1 million - but we're replacing the route into Euston though.
I just rounded the bridge superstructure costs (of £8m x 6) by £5m and rounded it up to £60m to £70 million. Ten times cheaper than £600m of tunnel to Euston.
If we add the St Pancras stuff up to say £120m we might get £200 to £250 million. All rather cheaper than £6 BILLION. And with private HS1 money funding a lot of it.

Q3: What are the results of the assessments you have made of the 80+ different technical and operational factors that have to be conducted when investigating the raising of linespeed? Horizontal alignment is just one of them.
When TfL trains are not limited to 15 mph, why are you saying that these trains cannot run at around 40 mph? This isn't rocket science. Other trains run this route at 40mph.
The curves at each end are around radii of 350 metres which most rail lines limit to around 40mph (eg 60 km/hr). You are splitting hairs here. Be fair.
(Or are you one of the people with a vested interest in wasting taxpayers money on a £6 billion Euston?)
I'm just trying to ensure that HS2 actually gets built into London! Right now that is at risk due to HS2 costs rising way too high.
Q4: What is your proposed solution if (when) it turns out that the previous studies (done by teams of professional engineers) that concluded rebuilding both the NLL tracks for GC gauge was impractical, is correct, and you can’t do the work without completely rebuilding the whole viaduct? What cost allowance have you made for this risk?
Arup's drawings clearly state that they are using the existing viaduct but relaying tracks and replacing steelwork over the bridges. Look at that drawing.
I didn't edit their text that talks about "skewing tracks for GC guage". And I've checked their measurements with a Disto to prove the viaduct is 8.4m wide.
Their professional engineers produced those drawings. TfL use the same viaduct. So do heavy freight trains. Why do you want to rebuild it?

As for train turnaround times, look at TfL trains which turn in 2 minutes. These are only 200 metre long classic trains where the driver needs 2 minutes to walk to the end.
And about 1/3rd of passengers wouldn't be getting off them. These are through trains reversing. At rush hour we could even use stepping back (with a driver waiting at the end).
I have allowed for 5 minute turnarounds within 7.5 minute slots - ie exactly what Frankfurt HbH does with ICE trains. But I suggest that for most trains 4 minutes is enough.
It's about time we copied best practice from either Frankfurt or Tokyo instead of having a can't do attitude.

Look at where those Javelins go. Two per hour at rush hour really do only go to Ashford. But I gave 3 ways to solve the 7 trains/hr issue.
I like temporary use of platform 10 best, with that combined with sending some Birmingham trains (normally turning in a double slot at St Pancras but extended to Ashford in rush hour to postpone their use of the return slot until after rush hour). That combination adds an extra 15 slots of 7.5 minutes each over say 90 minutes. Room for expansion!

Q5: On what basis have you decided that a repeated 7.5 minute (or 6 minute) departure to departure turnround is in any way practical or physically possible for 200m / 400m high speed rolling stock with intercity door arrangements and long distance passengers potentially with luggage etc? Note how long it takes any long distance train at Euston or Kings Cross to be empty of passengers from the moment it receives a proceed aspect on the home signal, and how long it takes to reload, depart, and then clear the fouling point for the platfrom line on departure. (I have studied this, at length, several times during my career).

On the basis that I have video evidence of Bullet trains being terminated and turned in Tokyo and have used Frankfurt HbH many times and studied the timetable.
I have timed people getting off Eurostar trains with luggage. I have seen High Speed trains arrive and depart in those times elsewhere.
And on the basis that Metro trains do this in this country all of the time. Why is 7.5 minutes too short a time to just reverse a 200 metre long train? (none are 400m ones).
400m trains are another subject for the "Eurostar" platforms when HS1 gets their deal with Virgin or whoever sorted out. Not for now.

Q6: What cost allowance have you made for gaining the necessary consents to build and operate the new lines, including the legal processes, land purchase, and compensation to nearby affected property owners, businesses and residents who will be affected by the work and the end result?

This is an "upgrade of an existing railway" - so the bridges only need Camden Council's planning permission. Network Rail is allowed to upgrade existing railways with only local planning permissions.
Railway Land north of Juniper Crescent is within the HS2 Limit of Deviation too.

I keep telling you that only one property needs any land purchase. As this is an existing railway, these electric trains would make less noise than diesel freight trains. What "compensation" when residents chose to live by this existing railway?
And yet again, what "land purchase"? Stop repeating misinformation.
There is only one property affected. Camden Market is unaffected.
Road traffic would be the main concern for the 6 week periods needed to replace bridge superstructures (eg Whalley Bridge took that long for £5.1m). That (and the design of road bridges) would be Camden Council's main concern.
We are also after all now going to "fast track planning" in order to boost growth.

This project does exactly that - as it provides platforms for less money and boosts passenger demand by providing far better interchanges than a Euston dead end.

Q7: What is your proposed solution for turning trains at Stratford to/from the west, and what cost allowance have you made for this work to be done? If such an engineering solution is not reasonably practical, where do you intend to send the trains and what work is necessary for that to happen?
Despite it being pointed out to you, repeatedly, that you cannot currently turn trains at Stratford International to/from the West, you keep suggesting it.

Look at the west end of the route up to Temple Mills depot. Those same tracks just need to X connect across to tracks to central platforms either side. An easy change.
So it IS INDEED possible to terminate trains on the central platforms of Stratford. Over the weekend, I could draw it for you - but I'm sure you can see what I mean.
These 200m long terminating trains would then use the central platforms. Through trains would use the outer platforms.
Nothing would then cross the fast lines in the wrong direction. I agree that Ebbsfleet is easier to use for 400m train terminations as platforms are all between the fast lines.

Q8: What is your proposed solution for the signalling of Javelin services on HS2, and HS2 services into St Pancras and onto HS1, and what cost allowance have you made for this? Currently, it is three different signalling systems (HS2 is ETCS L2 with ATO, HS1 from the London tunnels eastwards is TVM430, St Pancras area is KVB.)

Again, I don't claim expertise except to say its up to you to solve it - without that costing £6 billion. If you can't, then we risk not getting HS2 into London.
Stop finding obstacles and start finding solutions. It is crazy to have incompatible signaling solutions and HS1 have already said they want better compatibility with ETCS.
HS1 are thus already in the process of changing to ETCS according to recent publicity. Let them get on with that and let's make sure Javelins get the kit.
Check this link which shows that HS1 are indeed already upgrading to ETCS - https://www.railengineer.co.uk/upgrading-the-continental-connection/

Q9: What conclusion have you reached when assessing the capacity of the power supply on HS1 to accommodate the extended HS2 services, in particular the capacity of the local distribution around St Pancras to accommodate trains arriving and departing every minute or so. What cost allowance have you made for this?
Again, there is a simple answer to this. That's for HS1 to fund. They would after all be benefitting by a huge boost in track and platform access fees. The government could long rent out HS1 for many more billions every time they do so. This all boosts demand on both HS1 and HS2 - so money can be found to add a little extra power supply.
Its a lot cheaper than £6 billion.

Finally, you are suggesting sending internatonal services to OOC, and Javelins to Heathrow. The only practical solution to link HS2 to Heathrow would be to significantly expand the already finished Victoria Road crossover box, and bore tunnels from there to somewhere on the GWML in the Ealing area.

I have suggested 2 options.

Option 1 is to send 4 Javelins/hr (maybe more at rush hour) to terminate at OOC and 8 Classic compatible 200m HS2 trains/hr to terminate along all of the HS1 platforms (with most reversing within 7.5 minute slots at St Pancras.
View attachment 177335

Option 2 is to extend those Javelins to Heathrow or to Woking (via a ramp S curving through the OOC box - just like the ramp through Stratford Internation to Temple Mills) and free up the central platforms at OOC to receive some Eurostar trains.
An S curve reversable single track ramp through the station box to OOC GWR platforms doesn't need new tunnels (except for a short cut & cover at the top).
It almost all fits within the station box.

View attachment 177336


I agree that Option 2 involves border control facilities in OOC - (some glass screens and offices). It costs about £100m more. But it repays those costs annually from 2040.
By freeing up Paddington platforms for more GWR trains, by re-using the existing 4 slots to Heathrow from the Heathrow express and by boosting cross London passengers with lucrative fares from St Pancras or Stratford or Ashford to Heathrow it boosts revenue.
If the Staines link is built, those same trains could run to Woking and link the South Western network to Heathrow, OOC and St Pancras too.
The extra revenue coming from connecting all of these rail networks together would surely fund a short platform extension at Heathrow???

View attachment 177338



I'm just saying that the cost of reaching St Pancras and existing HS1 platforms is in the region of £250m with HS1 Ltd funding half of it (in return for track / platform access fees).
The cost of extending the Elizabeth Line to Ebbsfleet has been estimated north of £3 Billion - ie ten times more.
The Elizabeth line is already full. Its a metro (with no loos). Its not the same sexy alternative to cross London on express trains that only stop at Ebbsfleet, Stratford, St Pancras and OOC (plus possibly Heathrow and Woking with my "option 2").

Finally, I accept that you are the experts here. I'm just saying that without this sort of re-think of where HS2 trains terminate, we risk nothing getting built at all.
Euston isn't funded. The Government only wants to put about 4 platforms there. Please let's work together instead of shooting me down in flames. I'm a retired Architect who has worked on railway projects.
I am after all just a volunteer here.
And as I'm new to this site, (and was on holiday last week) it took a week for me to notice the tiny page number buttons. I thought my early replies were not getting posted. And I never saw your other questions.

None of this is a rethink. This was all discounted very early on.

We are not shooting you down in flames, we are telling you what just will not work work in quite some detail and you are refusing to accept reality, especially now you are saying we are the experts and its up to us to work it out, in quite a rude manner i must also add.

This sounds very much like low quality politician bait, a few shiny images and an idea that has some superficial merit and then falls apart the minute you scratch the surface.

Your basis for making things cheaper seams to be to make someone else pay for it, its just false accountancy.

There are irrelevant comparisons present such as bridges in Whalley bridge.

You mention the Shinkansen in Tokyo and its turn around times, i dont recall it having a swift turn around time, considering they will generally unload and turn all the seats before reloading and heading out. They are however frequent.

What i think is more pertinent as a Tokyo example is that the two major Shinkansen routes, the Tokaido and Tohoku Shinkansen are at separate stations within Tokyo station itself and there is no physical connection with which to run through trains from South to North.

And being truly blunt and honest, i dont think you understand anything about the design and construction and operation of railways and are just trying to bluster your way through it.

 

[Benjwri]

I agree that Option 2 involves border control facilities in OOC - (some glass screens and offices). It costs about £100m more. But it repays those costs annually from 2040.

It also involves losing an entire island platform, given you cannot have international passenger mixing, and employing security, border, customs staff etc for a very small amount of trains. Who is going to pay for this?

 

[skyhigh]

But I suspect some of you are being paid to shoot me down?
We've had a feeding frenzy of HS2 consultant fees? The UK has been made a laughing stock by multiplying HS2 costs to 10 times what anyone else pays?

This is getting utterly ridiculous. Nobody is being paid to rubbish ideas on an enthusiast forum. Anyway, you hardly need others to shoot your ideas down. You're doing that perfectly well yourself!

 

[mmh]

As others have pointed out, even if every air passenger from Manchester airport swapped to rail you'd max out at 1tph.

You might get another 2tph from all the other airports.

However HS2 is based on 17tph, reducing that to 14tph isn't going to mean much of a reduction in the number of platforms in London.

One train per day, not hour.

 

[Harpo]

UK railway managers and consultants alike spent decades visiting Japan (nice), going ‘wow!’ and using the holy grail mantra ‘Japanese levels of reliability’ afterwards, but…..

There is little point in using other nations as exemplars of efficiency unless we can magically import their planning laws, politics, safety laws (usually less), regulatory regimes, politics, funding regimes, politics, passenger culture, workforce culture, etc..

Our own melange of these gave us the expensive (Japanese) Hitachi IET with their construction defects and availability issues as well as the ballooning HS2 costs. We ain’t Japan!

 

[The Ham]

One train per day, not hour.

Sorry my mistake.

 

[John Jefkins]

St Pancras has an upgraded tube station for the current use, and future growth. To add on additional use would use all that up and immediately need another upgrade.

Not for the numbers we are talking about from just 8 of the shorter HS2 trains/hr where 1/3rd would have got off at OOC and another 1/4 may be travelling through to Stratford or Ebbsfleet or Ashford.

That would end up too far north, heading for North Acton via a lot of living rooms.

Which living rooms please? Not one as this uses the existing railway route. Please explain.

Typically this doesn’t claw back all the money.

What is supporting those columns?

Concrete Seriously there is a concrete factory right there on site. There is room between the various tracks for columns to support a bridge across from the Midland Mainline side to the Canal crossing and Dock.
1km of 3 track route then.

Please do, because I can’t see it. The route to temple mills is above the platforms 2 and 3.

Crudely drawn, here is how the existing route to the Temple Mills S curve could have two extra tracks added to connect to the central platforms to allow trains to reach or reverse from the opposite platform.

If the cost of that extension could be said out loud, that question could be answered.

Surely these 200m long trains would fit in the existing platforms though? By the way, for any Heathrow extension of the Javelin service, we'd need new trains (that could be designed to fit). The shorter extension west to OOC uses existing trains.
Over the next 10 years we will need new Javelin style trains anyway.

Without wishing to demand your CV, what were those projects?

Channel Tunnel UK terminal at Folkestone (biggest project in Europe). Senior role. Other stations and DLR projects.

 

[zwk500]

Crudely drawn, here is how the existing route to the Temple Mills S curve could have two extra tracks added to connect to the central platforms to allow trains to reach or reverse from the opposite platform.
View attachment 177408

You can clearly see the beginning of the viaduct to the right of the bridge in this image which means the vertical gradients would not be permissible for these tracks. The geometry to fit in the available space also looks horrendous so would be a very low speed limit.

 

[John Jefkins]

This is getting utterly ridiculous. Nobody is being paid to rubbish ideas on an enthusiast forum. Anyway, you hardly need others to shoot your ideas down. You're doing that perfectly well yourself!

Fine. Then start helping instead of hindering.

Whilst you cannot compare the 15mph speed of a 700 metre long freight train with speeds that 200m long Javelin or HS2 trains would be allowed to run at along the straight tracks by Camden Town, I do accept that this idea needs to cope with better resilience in the St Pancras throat. You clearly have more expertise than me on that. I've had help from experts such as Civil Engineers and franchise planners (Commercial Directors of previous franchises) who proved the interchange penalty data.
But I'd value your expertise in getting this idea refined.

1) I am drawing up a way to get 3 "roads" into these Javelin platforms (plus platform 10) by (a) widening the existing NLL route to 2 tracks, (b) adding a 3rd reversable route across an overbridge (with a ramp alongside the NLL route and ramp down over the dock), (c) widening the faster curve from the NCML chord over the Midland Mainline to level cross the HS1 chord to provide 950m of 3 track route to the Javelin platforms all the way from St Pancras road bridge.
2) Charing Cross for example has 44 movements /hr at rush hour (22 trains in and 22 trains out) with a totally level throat and no overbridges to the same 4 tracks (as we'd have 2 to HS1 and 2 to HS2).
So we don't actually need to look at Japan or other regulatory authorities to find an example of UK practice where trains actually terminate in under 5 minutes. I just want to reverse a smaller number of them.

Lets look at the numbers again.
Javelin trains terminate on these same platforms within 10-12 minutes. I want to do exactly the same thing with 3 or 4 of the HS2 trains (eg 2 from Birmingham and 2 from Manchester) on platforms 11 or 12.
These busy trains don't need cleaning and restocking at both ends of their now very short journeys (45 mins from Birmingham). But I accept we do need to offer passengers 10 minutes to swop.

The other trains can be treated more like those Charing Cross commuter trains, except that a good 1/4 of the passengers will be staying on board - so less platform movement.
And we really can copy the Japanese technique of (a) sending people to platforms before trains arrive and (b) getting them to queue by the correct half door for their carriage to speed up boarding.
They even have two queues. One for the 1st train on the indicator. Another to board at the correct door for their half of the carriage for the 2nd train due to arrive. I bet the new Japanese owners of the Elizabeth line copy this idea


My resilience question to you is - is it better to allow longer slots (of 7.5 minutes) for each train or is it better to have lots of 6 minute slots with about 50% of them unused? -

ie
a) to use 20 movements of 30 slots of 6 minutes each - leaving 33% of them unused.
or
b) to use 20 movements of 24 slots of 7.5 minutes each - having longer slots with only 4 of them (adding up to 30 minutes per hour) unused.


With 4 tph terminating in about 12 minutes within 15 minute double slots, that leaves only 20 movements per hour in or out of these 3 platforms (Charing Cross has 44 out of 6 platforms).
We'd have 6 roads (3 towards HS1 and 3 towards HS2). We have bridges (unlike Charing Cross) that enable outbound trains to cross over or under an inbound train heading for the same platform.
Even if Eurostar doubled to 4 trains per hour (8 movements) and took 2.5 minutes to make each movement, that still leaves 40 minutes per hour to cross those tracks.
And during the time a Eurostar blocked the tracks, we could still have an HS1 train go the other direction at the same time as send or receive an HS2 train across the reversable over-bridge (from the dock to the NLL).

How can we work together to make this work better please?

 

[mr_jrt]

I can't help but feel a far better use of the disused NLL viaduct capacity would be to enhance the LO network...not that that's going to happen, mind, but still. I suspect you'd be better off extending the tunnel from OOC to the St P. approaches if you really have your heart set on all this. If nothing else, you'd already have some degree of grade separation to start from.

 

[John Jefkins]

You can clearly see the beginning of the viaduct to the right of the bridge in this image which means the vertical gradients would not be permissible for these tracks. The geometry to fit in the available space also looks horrendous so would be a very low speed limit.

There is another 90 metres of station box west of the point I have shown - so the z curves could extend west. And we're only talking about the speed to take these 200m long HS2 trains into a platform.
But I do agree that Ebbsfleet and Ashford are both easier sites to terminate trains.
If 4 of the 8 HS2 trains actually terminate in 12 minutes (in 15 minute double slots) at St Pancras, we'd be actually only sending 4 HS2 trains/hr down HS1 to use either Ebbsfleet or Ashford - eg 2 each there per hour.

There isn't just one way to do this. Let's work out a way to make this work. What would you suggest to help rather than just finding ways to hinder please.

Here is another quick sketch.
As you can clearly see, these curves and x junction does now avoid the beginning of the viaduct. The geometry is over 270 metres long so the available space is big enough to allow 35 to 40 mph into or out of these platforms.
This would be faster than presumably the Eurostar trains currently run onto the ramp up to Temple Mills.

I can't help but feel a far better use of the disused NLL viaduct capacity would be to enhance the LO network...not that that's going to happen, mind, but still. I suspect you'd be better off extending the tunnel from OOC to the St P. approaches if you really have your heart set on all this. If nothing else, you'd already have some degree of grade separation to start from.

A tunnel was the expensive solution rejected before. With trains needing to slow down anyway as they approach St Pancras, and with grade separation possible with a bridge over the St Pancras throat to the Boat dock, I don't see why an expensive tunnel is needed.

This isn't a high speed line here. Its more like Thameslink or Crossrail where we can pack 20 trains per hour between OOC and Stratford via St Pancras.

 

[zwk500]

There isn't just one way to do this. Let's work out a way to make this work. What would you suggest to help rather than just finding ways to hinder please.

My suggestion is to terminate HS2 at Euston, and make the interchange as smooth as possible. Through trains to the continent from beyond London will only make sense if we're part of Schengen or equivalent frictionless travel.

I'd absolutely get the ORR to grant access rights to a London-Continent competitor as well, most likely Virgin's proposal at the moment but maybe DB if they're interested.