High Speed Two (HS2) discussion

[Bonemaster]

Yet HSTEd will tell you it is all about bringing 'the north' into the 'commuter belt'. You see the problem - no one is exactly sure what it is for.

I believe you are wrong, I think everyone knows what it is supposed to be for, the current plan fails to achieve it, which leaves some people grasping straws to justify their opinion.

Stations at Meadowhall & Toton which are perfect for taking people out of the conurbations but not in, thus failing to generate the engine of growth in the regions.

The Milton Keynes, Coventry, Stoke issue (and to a lesser extend Leicester, however that would cost serious amounts to resolve) that means you still have to operate a significant number of higher speed services, which under the current plan eat up many of the potential extra paths for local commuters, and failing to solve the problem that the investment is supposed to resolve.

 

[JohnB57]

Well, I don't know about 'no one'. I do not understand why you take this tone in your contributions. I know what it is for and so does the Government and Opposition (even). It is for providing a long distance high speed route between our major centres of commerce. In England these are London, Brum, Manchester and Leeds. Sheffield, East Midlands and Airports are also being provided for. Other major cities will get access, thus also benefiting. The capacity relieved elsewhere (chiefly WCML and ECML) will be available for more pax and freight services than otherwise would be the case, in an ever-growing rail market.

That's it. I find it very simple to understand, to be honest.

Well I for one find Philip's contributions and scepticism entirely appropriate and interesting in the context of this debate. And you may have an answer to his query "what is it for", but your post doesn't provide it, you just explain what it does.

Yes, HS2 links the cities you mention - that much is clear even to the most agnostic of us. The question is not what it does, but what the purpose of all those thousands of additional journeys will be.

 

[deltic]

I can't speak for Philip Elliott but IIRC there are over 1 million rail journeys to/from Coventry and Euston per annum. Don't know the figures for Stoke - London though.

A few years out of date but I believe London-Stoke is around 0.5m
--- old post above --- --- new post below ---

I believe average load factor on IC WC services is around 35%, with it rising to around 55% during peaks. These figures were bandied about during the WCML bidding rounds.

I remember reading elsewhere that average load factor on IC EC services was around 45%. Don't know whether this figure is accurate though.

I never understand this debate about load factors - HS2 is projected to open in 2026 - given Thameslink 2000 is expected to open around 2018 and Crossrail also in 2018 (when some hoped it might open in time for the Olympics) - I would put money on it not opening till mid 2030s to Brum and mid 2040s to Manchester and Leeds. So present load factors are irrelevant its what will they be in 20-30 years time that is relevant.

Full details of WCML load factors can be found here https://www.gov.uk/government/publications/west-coast-main-line-demand-and-capacity-on-weekdays - and are a bit higher than quoted above

 

[HowardGWR]

Yes, HS2 links the cities you mention - that much is clear even to the most agnostic of us. The question is not what it does, but what the purpose of all those thousands of additional journeys will be.

The purpose of HS2 is to provide for those journeys, not to analyse their own purpose, other than to recognise that they are desired. It's called predict and provide and it's what the Government did with road building, until that became unsustainable. It would be quite possible to choke off demand by not building HS2 and at the same time to make the present routes undesirable by high prices, poor service and so on.

When you write of journey purpose, it's classed as either firm's business, journey to work (that's the Americanism 'commuting'), or leisure (shopping, tourism, visiting relatives, etc).

The CBR for HS2 and all transport schemes is based on what the predictions are for these uses. The journey time savings for each class are priced accordingly to their respective values. Travelling on firm's business is far more valuable than visiting one's aged aunt or watching a football match.

I presume that the HS2 reports (I have not read them all) contain the details of all these predictions and costings, and they must be held to be sound, otherwise opponents would have succeeded in their high court action, as one of their objections. They didn't, at least not on these grounds, so I assume that's the end of that. Going back to Philip Elliott's postings, I have long mislaid from memory what his original point was, but I understood he thought HS2 should have gone via places like Coventry, MK and Stoke (or was it that it shouldn't be built anyway?). Well, it doesn't go to those, neither does it go to Bradford, or Harrogate, or Huddersfield. Think of it this way; the M1 does not go to those places either, - so what does it matter, HS2 is just another transport scheme, just as GW electrification is.

Joining railways to HS2, just like joining roads to M1, can always be separately justified in future schemes, if the BCR looks good.

I simply do not understand what the debate here is supposed to be about, other than if one rejects the 21st century and all its opined unsustainable doings.

 

[Philip Elliott]

Well, it doesn't go to those, neither does it go to Bradford, or Harrogate, or Huddersfield. Think of it this way; the M1 does not go to those places either, - so what does it matter, HS2 is just another transport scheme, just as GW electrification is.

Except that there is the ability to do London - Bradford by motorway only and with the way they work, it is in effect a direct road. The M1 was the London to Leeds motorway but Leeds is something like Junction 42? So there are 41 (plus all the subsequent 'a' junctions) junctions where people can access it - many of the roads joined to it were upgraded at the same time. The same cannot be said of HS2 - access is appalling.

 

[HowardGWR]

Except that there is the ability to do London - Bradford by motorway only and with the way they work, it is in effect a direct road. The M1 was the London to Leeds motorway but Leeds is something like Junction 42? So there are 41 (plus all the subsequent 'a' junctions) junctions where people can access it - many of the roads joined to it were upgraded at the same time. The same cannot be said of HS2 - access is appalling.

Yes that's my point. When the first motorways were built they didn't go everywhere (still don't, thank goodness, in my view). Other schemes that joined them were subsequently put forward and still are being so put forward.

That's the same with what will possibly be a growing HS network. It will not surprise me in the least that once HS2 is built (and before that if the prognosis of demand is proven justified), more schemes will be suggested.

Thanks for reading my take on the issue.

 

[JohnB57]

Yes that's my point. When the first motorways were built they didn't go everywhere (still don't, thank goodness, in my view). Other schemes that joined them were subsequently put forward and still are being so put forward.

On the contrary, I believe you're missing the point, which is that access has always been good on the routes of our motorways, with further improvements made as and when necessary. HS2 will be unaccessible anywhere between west London and Birmingham and this merely to manipulate the BCR, itself designed around manufactured values and assumptions.

 

[tbtc]

HS1 will be unaccessible anywhere between west London and Birmingham and this merely to manipulate the BCR, itself designed around manufactured values and assumptions.

Well, yes, it runs to Kent.

Except that there is the ability to do London - Bradford by motorway only and with the way they work, it is in effect a direct road. The M1 was the London to Leeds motorway but Leeds is something like Junction 42? So there are 41 (plus all the subsequent 'a' junctions) junctions where people can access it - many of the roads joined to it were upgraded at the same time. The same cannot be said of HS2 - access is appalling.

On the one hand, HS2 gets criticised for being far too ambitious, on the other hand it gets criticised for not going far enough.

A railway line with forty one junctions between London and Leeds (and services joining/ leaving at all of them) would not be a high speed one.

 

[JohnB57]

Well, yes, it runs to Kent.

Thanks for the heads' up. Edited.

A railway line with forty one junctions between London and Leeds (and services joining/ leaving at all of them) would not be a high speed one.

...or even a High Speed Two!

On the one hand, HS2 gets criticised for being far too ambitious, on the other hand it gets criticised for not going far enough.

I know you weren't quoting me directly, but I certainly don't think it is too ambitious or even too expensive and I don't believe that much of the otherwise railway friendly criticism is based on that either.

A railway designed to have no access for half its length simply in order to achieve an arbitrary speed target required to satisfy an arbitrary BCR designed around arbitrary criteria, many of them invented just for the purpose...

You get my drift I hope.

 

[tbtc]

I know you weren't quoting me directly, but I certainly don't think it is too ambitious or even too expensive and I don't believe that much of the otherwise railway friendly criticism is based on that either.

A railway designed to have no access for half its length simply in order to achieve an arbitrary speed target required to satisfy an arbitrary BCR designed around arbitrary criteria, many of them invented just for the purpose...

You get my drift I hope.

You make an interesting point.

Personally its hard to defend HS2 from the criticism in the mainstream media/ general public *and* from railway enthusiasts, since a lot of it comes from opposite sides.

Such as the "HS2 is too expensive and ambitious" whilst also "HS2 doesn't go far enough" one. Or the "Why are we obsessed with saving fifteen minutes" whilst also "we are going to ruin Stoke by slowing its London services down by a few minutes" argument.

I've said in the past that I'd prefer something simpler (one line from London to Manchester via "Leamington", "Birmingham" and "Cheshire Parkway", no branches, not trying to solve every problem). This would leave scope for an "M1 corridor" high speed line at a later stage. Instead, what we have is something designed by a committee, a muddle that tries to serve too many markets with just one line.

I'd counter the "no access for half its length" argument by saying that there are currently a number of services that don't stop in the first hundred miles of their journey:

• London to Grantham/ Doncaster/ York (plus a token Wakefield service IIRC?)
• London to Stoke
• London to Stafford/ Crewe/ Warrington (and Preston once a week)

London to Leicester is a regular non-stop journey for EMT, but is just within the 100mile radius - however we are going to see non stop London to Bristol Parkway services when IEP comes in (IIRC).

This suggests that there's not enough of a market for services from northern England (or north Wales, Scotland) to Watford, Stevenage, Northampton, Rugby.

I've not seen the market research, I don't know what the figures used to justify this are, but I can certainly see that the railway doesn't think there's a big enough market to provide direct services from Hertfordshire/ Buckinghamshire/ Cambridgeshire/ Bedfordshire to Leeds/ Manchester etc.

 

[Haydn1971]

Coughs... There's a fast direct ECML train from Leeds to Stevenage every hour, plus a few direct Manchester to Rugby trains in the morning...

Is it more a case that rail doesn't provide these secondary choices because there's more cash to be made on the London run ?

 

[NotATrainspott]

Coughs... There's a fast direct ECML train from Leeds to Stevenage every hour, plus a few direct Manchester to Rugby trains in the morning...

Is it more a case that rail doesn't provide these secondary choices because there's more cash to be made on the London run ?

If Virgin can fill up an 11-car Pendolino by Warrington, or East Coast an IC225 by York, then running non-stop to London isn't then harming their bottom line. It also makes sure that seats on these trains are used by people who need them rather than by commuters wanting to save a few minutes off their commute. You can still have services on top of these to connect up the remainder of people; Virgin's stopping services from Glasgow to Euston via New Street are there for more than just saving diesel-under-wire running. Also if you're travelling between intermediate stops then journey times won't be as crucially important due to the lesser competition from air versus the lucrative, fast and frequent capital-to-captial runs. The rail-vs-air comparison for journeys not including London will be considerably less biased towards air because of the lesser frequency of flights and the slower turboprop aircraft used (GLA-BHX takes the same time as GLA-LHR).

 

[YorkshireBear]

Surely the point of HS2 allows the long distance services to call at these places on existing network opening up these journey opportunities?

 

[Philip Elliott]

I'd counter the "no access for half its length" argument by saying that there are currently a number of services that don't stop in the first hundred miles of their journey:

• London to Grantham/ Doncaster/ York (plus a token Wakefield service IIRC?)
• London to Stoke
• London to Stafford/ Crewe/ Warrington (and Preston once a week)

London to Leicester is a regular non-stop journey for EMT, but is just within the 100mile radius - however we are going to see non stop London to Bristol Parkway services when IEP comes in (IIRC).

This suggests that there's not enough of a market for services from northern England (or north Wales, Scotland) to Watford, Stevenage, Northampton, Rugby.

I've not seen the market research, I don't know what the figures used to justify this are, but I can certainly see that the railway doesn't think there's a big enough market to provide direct services from Hertfordshire/ Buckinghamshire/ Cambridgeshire/ Bedfordshire to Leeds/ Manchester etc.

In the case of London to Stoke there are three trains per hour, one is non stop, one calls at MK only and one calls at MK, Rugby, Nuneaton, Tamworth, Lichfield, Rugeley, Stafford, Stone so there is access along the route.

HS2 will pass Aylesbury but anyone from there wanting to go to Leeds will have to take a train to either MK or Princes Risborough, change services for a Birmingham service then change again to a different station - a very long winded route.

Surely the point of HS2 allows the long distance services to call at these places on existing network opening up these journey opportunities?

If these long distance services continue to run, then there won't be the space for commuter and freight trains.

 

[YorkshireBear]

In the case of London to Stoke there are three trains per hour, one is non stop, one calls at MK only and one calls at MK, Rugby, Nuneaton, Tamworth, Lichfield, Rugeley, Stafford, Stone so there is access along the route.

HS2 will pass Aylesbury but anyone from there wanting to go to Leeds will have to take a train to either MK or Princes Risborough, change services for a Birmingham service then change again to a different station - a very long winded route.




If these long distance services continue to run, then there won't be the space for commuter and freight trains.

Does Stoke need three trains an hour to London? No. Just as Chesterfield doesn't need two.

AH but these long distance services if calling at Milton Keynes and Peterborough and Stevenage etc become commuter services closer to London. Then there won't be as many required too so other services can fit in. Then in addition no trains will be running non stop eating up all the capacity so an extra few paths are gained there too. Freight is only going to gain 2 paths an hour on WCML nothing more.

 

[NotATrainspott]

HS2 will pass Aylesbury but anyone from there wanting to go to Leeds will have to take a train to either MK or Princes Risborough, change services for a Birmingham service then change again to a different station - a very long winded route.

Aylesbury has a population of 58,740. The vast majority of whom are interested more in travelling to London than anywhere else. The number of people who would be interested in travelling north is therefore going to be tiny and simply isn't worth the time, money and disruption caused by stopping there. HS1 has domestic services only because there is no other LDHS route through Kent and these services are run with 120m long 225km/h trains which then have to go off and go around Kent to pick up passengers. The WCML and CML aren't being mothballed and they will continue to serve these towns, and more frequently at that. 6tph at the normal or slightly slower speed is still more attractive than 3tph at the current speed, especially if the time difference is less than 10 minutes.

There is simply not enough demand for people to go from Aylesbury, or the Chiltern in general, and go to Leeds. The towns in the Chilterns are inhabited by people who want to go to London, whether to commute or to go regularly for leisure or other purposes. They already have several lines which serve that need, all of which will have their services improve for these people once HS2 is built as almost every train will stop at the stations.

 

[edwin_m]

HS2 will pass Aylesbury but anyone from there wanting to go to Leeds will have to take a train to either MK or Princes Risborough, change services for a Birmingham service then change again to a different station - a very long winded route.

If they went to Moor Street the HS2 Birmingham station would be immediately alongside. There is some benefit for these people as the journey to Leeds would have the same number of changes as today but would be quicker due to high speed running on the Birmingham-Leeds leg.

I do however see the point that Buckinghamshire gets no benefit from the part of HS2 that runs through it, but it's pretty much impossible to do anything about that. In that sense a M1 corridor route would have been better because even if it had no intermediate stops the local population would benefit directly from WCML capacity release.

 

[HowardGWR]

The reason motorways are not high speed is because they have so many exits and entrances (apart from being lethally dangerous at any higher speed limits). We've all travelled on them and we know just how tiring it is to travel a long distance with uncontrolled fellow users weaving in and out unpredictably, to name but one hazard. They are in fact a series of local bypasses joined together and one can travel from end to end fairly quickly but not viably for long distance fast business and leisure travel. They cannot handle peaks well either.

That is the justification for HS lines. If they have too many junctions for other services to 'join in and leave', they become unviable for the traffic for which they are designed.

The BCR for HS2 stacks up as it is and does not need further junctions. HS2 may justify extensions to Scotland and if that meant a pressure on its capacity, it might be necessary to build another HS line or duplex the one already there as far as, say, Brum.

It may be in future possible to justify a Middle England HS line that goes direct non-stop to Leicester and then Nottingham and Sheffield, who knows?

 

[Bonemaster]

Aylesbury has a population of 58,740. The vast majority of whom are interested more in travelling to London than anywhere else. The number of people who would be interested in travelling north is therefore going to be tiny and simply isn't worth the time, money and disruption caused by stopping there. HS1 has domestic services only because there is no other LDHS route through Kent and these services are run with 120m long 225km/h trains which then have to go off and go around Kent to pick up passengers. The WCML and CML aren't being mothballed and they will continue to serve these towns, and more frequently at that. 6tph at the normal or slightly slower speed is still more attractive than 3tph at the current speed, especially if the time difference is less than 10 minutes.

There is simply not enough demand for people to go from Aylesbury, or the Chiltern in general, and go to Leeds. The towns in the Chilterns are inhabited by people who want to go to London, whether to commute or to go regularly for leisure or other purposes. They already have several lines which serve that need, all of which will have their services improve for these people once HS2 is built as almost every train will stop at the stations.

This point of view, whilst I agree with it (because of my second point) assumes that any station in Aylesbury will simply serve the conurbation rather than the surrounding Chilterns, the Thames Valley, and the Milton Keynes Area.

Secondly it assumes that the well paid jobs that people commute into London for currently all stay in London, and growth does not occur in the North, if this is true, it will create a northbound market that does not currently exist surely. Unless the HS2 proponents are wrong.

 

[33Hz]

With all the "money no object" tunneling that is proposed on HS2 line, why didn't they approach Birmingham from the south, under the city, then rejoin the WCML axis on the north side?

Building a cul-de-sac for Britain's second city (and a NE facing one at that) seems to me absolutely chronic short-termism. Especially with cities elsewhere upgrading such termini to through lines.
--- old post above --- --- new post below ---

This point of view, whilst I agree with it (because of my second point) assumes that any station in Aylesbury will simply serve the conurbation rather than the surrounding Chilterns, the Thames Valley, and the Milton Keynes Area.

Secondly it assumes that the well paid jobs that people commute into London for currently all stay in London, and growth does not occur in the North, if this is true, it will create a northbound market that does not currently exist surely. Unless the HS2 proponents are wrong.

I wonder what proportion of the population already commute into London?

If they had an HS station there, is it going to allow more of them to commute to London or bring more Londoners to that area - with associated countryside ruining housing developments?

 

[tbtc]

HS2 will pass Aylesbury but anyone from there wanting to go to Leeds will have to take a train to either MK or Princes Risborough, change services for a Birmingham service then change again to a different station - a very long winded route

What demand is there to go from Aylesbury to Leeds? Or are you just linking random places?

At the moment, since there's obviously no direct service from Aylesbury to Leeds, you'd need to go into London and back out again (so Aylesbury - Marylebone, Marylebone - Kings Cross, Kings Cross - Leeds - does this meet your definition of "a long winded route"?).

ETA - In fact, National Rail Enquiries suggest Aylesbury - Marylebone, Marylebone - Oxford Circus, Oxford Circus - Kings Cross, Kings Cross - Leeds if I were to do the journey tomorrow!

 

[Drsatan]

What demand is there to go from Aylesbury to Leeds? Or are you just linking random places?

At the moment, since there's obviously no direct service from Aylesbury to Leeds, you'd need to go into London and back out again (so Aylesbury - Marylebone, Marylebone - Kings Cross, Kings Cross - Leeds - does this meet your definition of "a long winded route"?).

If a station near Aylesbury were to be built on HS2, it would just be for commuters heading to and from London. Given that services heading northbound would have to be set down only and services heading south would be pick up only (to ensure only London commuters use the station), building a station there would be pointless.

 

[tbtc]

If a station near Aylesbury were to be built on HS2, it would just be for commuters heading to and from London. Given that services heading northbound would have to be set down only and services heading south would be pick up only (to ensure only London commuters use the station), building a station there would be pointless.

Agreed.

I think that the Chiltern lines (including the Aylesbury branch) will be electrified well before HS2 is opened - whilst I appreciate that NR only commit to five years worth of infrastructure at a time (the control periods), its a shame that someone in Government hasn't committed to electrifying routes through the Chilterns in the next decade (so that the "longer trains with better acceleration, new rolling stock" could be used to prove to the people living in this AONB that the local trains for local people are also being improved.

 

[jon0844]

The reason motorways are not high speed is because they have so many exits and entrances (apart from being lethally dangerous at any higher speed limits).

I have to disagree about them being lethal at any higher speed limits. Germany can prove that, as well as many other countries that have a higher speed limit than us (130kph). Even Sweden, a country known for being so safety mad, is increasing speed limits throughout the country as it upgrades the roads (new surfaces, barriers etc).

However, I would concur that our standards of driving here probably would make it more dangerous - but I feel that despite our motorways being the safest roads, they're more dangerous than they should be because of terrible lane discipline and drivers unable to judge speeds, thus having no issue pulling out in front of a car going MUCH faster.

Again, in Germany, people are used to this and so you can have someone doing 200mph in lane two, and a caravan being pulled in lane one at 50mph, and not have the same risk.

We can blame our attitude to catering for the lowest common denominator as a matter of course for this, and many other things, where we just don't seem capable of bettering ourselves.

Anyway, sorry for going off topic, although the bit about not wanting to better ourselves is perhaps still relevant for HS2!

 

[HSTEd]

Because underground stations cost ridiculous sums of money, money that is not available.

 

[MarkyT]

If a station near Aylesbury were to be built on HS2, it would just be for commuters heading to and from London. Given that services heading northbound would have to be set down only and services heading south would be pick up only (to ensure only London commuters use the station), building a station there would be pointless.

I don't see the point in such restrictions although whether these or any other limitations were neccessary or not, such a step change in commuting speed on the new route alone could result in massive extraction from other surrounding commuter routes into London, and huge increases in road traffic on local roads heading to and from the new station. Regardless of the additional HS2 costs and the effects on capacity for fast trains, an intermediate stop could seriously affect the viability of the Chiltern Railways operation and perhaps to a lesser extent GW Oxfordshire services and even outer the suburban LM business. Hardly good value for money except perhaps for those privileged enough to have sole access to a car they can leave at a country station all day and afford the presumably premium fares, nor enviromentally friendly if it results in increased road traffic over existing commuting patterns. I say leave the new HS2 tracks to the expresses heading to Birmingam and beyond and develop local commuter services along the traditional routes where some capacity is released by HS2 and which have existing stations closer to where people actually live.

 

[The Planner]

The reason motorways are not high speed is because they have so many exits and entrances (apart from being lethally dangerous at any higher speed limits). We've all travelled on them and we know just how tiring it is to travel a long distance with uncontrolled fellow users weaving in and out unpredictably, to name but one hazard. They are in fact a series of local bypasses joined together and one can travel from end to end fairly quickly but not viably for long distance fast business and leisure travel. They cannot handle peaks well either.

Surely being bypasses of towns and cities is partly the point of them? To remove the through traffic that doesnt want or need to be there. That just smacks of all motorways are bad and should never have been built.

 

[trainplan1]

What demand is there to go from Aylesbury to Leeds? Or are you just linking random places?

At the moment, since there's obviously no direct service from Aylesbury to Leeds, you'd need to go into London and back out again (so Aylesbury - Marylebone, Marylebone - Kings Cross, Kings Cross - Leeds - does this meet your definition of "a long winded route"?).

ETA - In fact, National Rail Enquiries suggest Aylesbury - Marylebone, Marylebone - Oxford Circus, Oxford Circus - Kings Cross, Kings Cross - Leeds if I were to do the journey tomorrow!

Remember East-West, when that comes along people from Aylesbury will be able to travel to Bedford and MK. Bedford means connections to stations to the MML (Leicester, Loughborough, Derby, Nottingham, Sheffield etc). At MK that means connections to the... WCML (Manchester, Birmingham, Chester, Holyhead, Birmingham, Wolverhampton, Lancaster, Carlisle, Glasgow, Edinburgh etc... All this without travelling into London!

Poor people of Aylesbury getting all these future travel options, they won't know what to do with themselves...

 

[Geezertronic]

With all the "money no object" tunneling that is proposed on HS2 line, why didn't they approach Birmingham from the south, under the city, then rejoin the WCML axis on the north side?

Building a cul-de-sac for Britain's second city (and a NE facing one at that) seems to me absolutely chronic short-termism. Especially with cities elsewhere upgrading such termini to through lines.

That would certainly be an approach I would favour, especially if it took some pressure off New Street by diverting services to it instead. All this tunnelling under the Chilterns and they seem to ignore the main requirements for Birminghams City Centre station (and one could argue Euston as well). The only issue might be that a high speed alignment might not be possible but one may not be needed if all services stop there

 

[NotATrainspott]

That would certainly be an approach I would favour, especially if it took some pressure off New Street by diverting services to it instead. All this tunnelling under the Chilterns and they seem to ignore the main requirements for Birminghams City Centre station (and one could argue Euston as well). The only issue might be that a high speed alignment might not be possible but one may not be needed if all services stop there

You would need a lot of platforms, each 400m long and at least 15m wide for an island. The only economical or technically sensible way of building such an underground structure is to have a station box, so the only way Birmingham would get a through station would be if there were an OOC or Stratford (pre Olympics) sized brownfield site right in the middle of the city centre, which there isn't. The cost of the station would rival that of entire sections of the route and there just isn't enough demand yet for that level of service.

If a through station is ever going to be built it would be well in the future when the South Wales/Bristol/Wessex to Birmingham XC route is saturated. Then you won't need just as big a through station so the costs won't be as extreme.

The only through route for InterCity services I ever see happening through London is for between a GW and an EC HSR route because there won't be enough terminating capacity at either Paddington or Kings Cross/St Pancras. HS2 to Euston hasn't got anywhere else to go than HS1 and only a tiny minority of services would ever need to go through to the Continent, even in the most optimistic of scenarios.