Where would you like to see Crossrail 3 go?

[NorthKent1989]

Ideally Crossrail 3 should run right across South of the River, the Windsor/Reading lines to the Dartford Routes and possibly the stopping service to Sevenoaks.

If not then it will be on a SE-NW Line, the Dartford routes to the Chiltern/Aylesbury lines

 

[The Ham]

Rather than moaning that HS2 isn't doing anything for these cities then maybe you should be looking at how you can make it be a benefit for these cities and the areas around them.

Following on from this I've started a thread asking where people would like to improve the classic network:

https://www.railforums.co.uk/thread...al-rail-after-the-introduction-of-hs2.169096/

 

[Mikey C]

My answer is a link to this map which shows what the tube network may look like in 50 years time (note not my work):

https://ukfree.tv/styles/images/2014/Tube2050/London Infrastucture Plan 2050 Transport v6.svg

(It shows CR3 as Twickenham/Wimbledon running to Waterloo, London Bridge, Canary Wharf before heading off to Rainham).

Just noticed that the map has Brent Cross with an OSI to Brent Cross Thameslink of 1600m! I doubt too many would be using that one

 

[The Ham]

Just noticed that the map has Brent Cross with an OSI to Brent Cross Thameslink of 1600m! I doubt too many would be using that one

Maybe there's going to be a underground cycle route with "Boris Bikes" for use at each end. That might get you into double figures for the daily flow!

 

[Lexicon10uk]

Yes. Absolutely. Metroland/Chilterns join CR1 through Central London and maybe take up the Abbey Wood branch and extend it to Ebbsfleet International. Then the Circle Line can be increased in frequency or the Wimbleware extended to Moorgate.

Why Ebbsfleet? Gravesend is a far better choice. Also Hoo Jct is a couple of miles east and safeguarded for turnback/depot facilities. Ebbsfleet lacks a large population unlike Gravesend and also easy interchange for the Medway Towns.
The idea that commuters from Broadstairs or Deal would pay for a HS1 ticket (including premium), only to get off at Ebbsfleet and embark upon a 35 minute trek to Canary Wharf, instead of remaining on the aforesaid HS service and using the super quick DLR from Stratford International, is frankly daft and will not happen with sufficient numbers. Crossrail understands that.
The main peak hours revenue stream beyond Dartford, is Gravesend. The main interchange station beyond Dartford, is Gravesend. The latest 'big idea' by the garden city (central government plaything), is to extend Crossrail to the south side of the current station building at Ebbsfleet. By doing so would prevent the service reaching Gravesend and be too out of the way and inconvenient, to be of any substantive use to Gravesend.
Again Crossrail acknowledges that.

 

[HSTEd]

Re the ‘deeper level railway than anything we have now’ - the trouble with that is that there is still a lot of stuff at deeper levels, and more importantly unless said railway is going to go across London without stopping, you have to build a station. And stations need access to ground level, and lots of tunnels to get from ground level to railway level. Through that already congested ground.

Of course anything’s possible, within the laws of physics, but there are consequences.

There are improving options for accessing tunneled facilities though.
For example, the Thyssen Krupp 'MULTI' system might allow a single up and a single down tunnel to move vast numebrs of people from the surface to deep levels easily.

And since the lifts can change direction they can go around obstacles. And it can obviously go straight down as required.

 

[4-SUB 4732]

Crossrail to Ebbsfleet is a stupid idea anyway - I appreciate this is off topic.

Crossrail should go to Gravesend and the Medway Towns; potentially also covering the Southeastern franchisee's Maidstone West peak services (in the event that High Speed all route via Rochester in 2021).

Equally important is to what extent the new Paramount Theme Park will cause issues and whether said attraction will necessitate some sort of surface rail connection e.g. to go off under Northfleet on the alignment of where the freight traffic goes or other.

 

[Mikey C]

Crossrail to Ebbsfleet is a stupid idea anyway - I appreciate this is off topic.

Crossrail should go to Gravesend and the Medway Towns; potentially also covering the Southeastern franchisee's Maidstone West peak services (in the event that High Speed all route via Rochester in 2021).

Equally important is to what extent the new Paramount Theme Park will cause issues and whether said attraction will necessitate some sort of surface rail connection e.g. to go off under Northfleet on the alignment of where the freight traffic goes or other.

But it would give a new connection from SE London and Dartford to Ebbsfleet, rather than duplicating the existing connection to Gravesend

 

[4-SUB 4732]

But it would give a new connection from SE London and Dartford to Ebbsfleet, rather than duplicating the existing connection to Gravesend

Realistically, the link isn't needed. A simple bridge or decent walkway (etc) from Northfleet to Ebbsfleet would resolve the matter. You could even re-name Northfleet to "Ebbsfleet North" and have it similar to Dalston Junction / Dalston Kingsland which isn't overly tedious.

 

[HSTEd]

Given the service limitations on the Metropolitan caused by the share section and shortage of terminal platforms at Baker Street, diverting the Metropolitan line is an obvious move.
You could then intensify the Hammersmith and City Line service to pick up the slack along Euston Road, and transfer the Aylesbury services to London Underground.

The question of where it goes from there is more complicated, but I think via Waterloo and Kennington is an obvious option.

 

[PeterC]

Given the service limitations on the Metropolitan caused by the share section and shortage of terminal platforms at Baker Street, diverting the Metropolitan line is an obvious move.
You could then intensify the Hammersmith and City Line service to pick up the slack along Euston Road, and transfer the Aylesbury services to London Underground.

The question of where it goes from there is more complicated, but I think via Waterloo and Kennington is an obvious option.

For the northern side I agree, take the Met main line and Aylesbury via Missenden. Perhaps also the DC lines. No idea where to go south of the river but the amount of tunnelling under central London will dicate a lot of the route. With money to burn I would throw in a travelator from Marylebone / Baker Street Crossrail to Paddington Crossrail platforms.

 

[si404]

Given the service limitations on the Metropolitan caused by the share section and shortage of terminal platforms at Baker Street

You mean dwell times at Finchley Road...

Though the shared section is a problem - because many Met line passengers want The City, and the less popular Hammersmith - City journeys take half the paths, rather than the roughly a third that numbers would suggest. And the capacity problems on the Met upstream of Harrow are more the shortage of trains given to Rickmansworth, etc due to oversupply at Watford and Uxbridge in order to aid GLA customers rather than try and distribute loadings on trains more evenly.

Ricky and beyond won't take too many trains. With full-length trains, rather than short ones, 10tph would be enough at peak.

 

[HSTEd]

For the northern side I agree, take the Met main line and Aylesbury via Missenden. Perhaps also the DC lines. No idea where to go south of the river but the amount of tunnelling under central London will dicate a lot of the route. With money to burn I would throw in a travelator from Marylebone / Baker Street Crossrail to Paddington Crossrail platforms.

There is no particular need for the lien to start and finish on opposite sides of the river though.

The Jubilee line crosses into South London before returning to the North to terminate at Stratford.

We could divert the Met via Waterloo and have it terminate in the Docklands if we wanted.

 

[Ronnie268]

I don't know why everyone is trying to divert/extend the Met. It's already full EB in the peaks (so shouldn't be extended significantly North/West), and the empty capacity is needed at Liverpool St WB in the peaks to clear the otherwise rammed platforms (so shouldn't be extended South/East/diverted elsewhere).

Everyone would love 36tph on the Hammersmith & City, but that obviously doesn't work with the District line east of Aldgate East. If you wanted to sort the whole subsurface, the only moderately sensible (by which I mean the smallest possible) intervention would be to provide 4 platforms at Aldgate East with overruns and to fiddle with Earls Court until you could run 3 self-contained, mostly conflict-free, 36tph metro operations: Richmond-Edgware Road, Wimbledon-Upminster, Aldgate East-Hammersmith/Uxbridge/Watford/Amersham/Chesham.

Even that isn't obviously much better than the existing. You lose direct connectivity from the East to the King's Cross and Paddington areas. But it has a broadly similar ethos to the Northern line separation, where less-frequent, direct trains are replaced with an increased overall frequency and good interchange at a midpoint (Camden Town - in this case Aldgate East). The point I'm trying to make is that there's no point undertaking massive tunneling to extend/divert the SSL lines when new tunneling for a new line would be just as cheap.

 

[Ianno87]

I don't know why everyone is trying to divert/extend the Met. It's already full EB in the peaks (so shouldn't be extended significantly North/West), and the empty capacity is needed at Liverpool St WB in the peaks to clear the otherwise rammed platforms (so shouldn't be extended South/East/diverted elsewhere).

The Elizabeth Line will help relieve the westbound platform at Liverpool Street (e.g. those bound for Paddington)

 

[Ronnie268]

The Elizabeth Line will help relieve the westbound platform at Liverpool Street (e.g. those bound for Paddington)

I'm sure it will somewhat, but I think it's prudent to wait until we see that before allocating the capacity elsewhere. It seems always to be the case that 'spare' capacity never seems to be spare for very long.

Great Eastern frequencies will increase as they'll have the extra platforms (15-16) at Liverpool Street that TfL Rail currently uses.

West Anglia capacities are increasing, with the new Class 720s.

Besides, the Elizabeth Line may well be rammed on arrival, considering it will pick up the existing 15tph of TfL Rail customers, plus people from the Abbey Wood branch, plus punters from the overground.

 

[si404]

I don't know why everyone is trying to divert/extend the Met. It's already full EB in the peaks (so shouldn't be extended significantly North/West), and the empty capacity is needed at Liverpool St WB in the peaks to clear the otherwise rammed platforms (so shouldn't be extended South/East/diverted elsewhere).

If there's a Crossrail take over of the Met Main, then, as long as that line serves The City, then those journeys are served by those trains. And you'd also have bigger trains at higher frequency, so trains less full.

That said, while it is a major capacity gap, and an area dear to my heart, I don't think it's necessary - longer Chiltern trains and diverting a couple of Met trains from Watford and Uxbridge, as I said upthread, would sort the problem without creating other problems. It's a bit sledgehammer to crack a nut!

Everyone would love 36tph on the Hammersmith & City, but that obviously doesn't work with the District line east of Aldgate East.

You terminate half the trains at Aldgate, run a quarter to Barking and the final quarter to Edgware Road via Victoria duh!

Not that I would love 36tph on the Hammersmith branch. Overkill that just does the 'Uxbridge needs 12tph, and Rickmansworth only 6tph' thing of assuming closer-in = more worthy of service. Met line trains are more crowded, despite being bigger.

The Elizabeth Line will help relieve the westbound platform at Liverpool Street (e.g. those bound for Paddington)

Because those full Met trains leaving Liverpool Street have lots of people heading to Paddington?

 

[Mikey C]

My impression is always that the through Met trains are less busy than the H&C/Circle ones anyway. 12 tph from Hammersmith/Paddington is pretty poor, when you consider all the passengers from High St Ken changing to join the service at Edgware Road.

Yes Crossrail will help a bit, but a lot of people are going to Baker Street, Euston and Kings Cross St Pancras.

 

[DynamicSpirit]

Crossrail to Ebbsfleet is a stupid idea anyway - I appreciate this is off topic.

Crossrail should go to Gravesend and the Medway Towns; potentially also covering the Southeastern franchisee's Maidstone West peak services (in the event that High Speed all route via Rochester in 2021).

Why should it go to Gravesend? From my experience, even in the peaks, SouthEastern trains tend to be relatively empty east of Abbey Wood. So you'd be adding more trains to a route that doesn't - so far - appear to need them (though I appreciate that numbers will grow when Crossrail arrives at Abbey Wood and also in a few years if/when the proposed new housing around Belvedere is built). People at Gravesend who want to get into London quickly are most likely to use HS2 (which, if the few times I've used it are anything to go by, does face overcrowding issues so could well do with either longer or more frequent trains).

 

[NorthKent1989]

What’s with this idea of extending the Met down to SE London?

I can understand the rationale behind it, but it’s in a tight spot in the city end of the line, I'm not certain it could actually be done, I think (and sorry for going slightly off topic) that the Met is probably better off being cut back to Baker Street and become part of London Overground, it’s 90% a suburban rail line anyway, therefore leaving the Hammersmith & Circle to run more trains along east of Baker Street.

As for Crossrail to Gravesend, It’ll be better if it does reach there, you can create a travelator link between Northfleet and Ebbsfleet stations to create an interchange between the two, Crossrail will be very useful since it’ll actually serve the Docklands, City and West End all one line, places where people want to go without paying premium, not sure if Crossrail will ever make it to Medway, TfL seem pretty iffy about expanding its services that far out.

 

[Altnabreac]

Given the service limitations on the Metropolitan caused by the share section and shortage of terminal platforms at Baker Street, diverting the Metropolitan line is an obvious move.
You could then intensify the Hammersmith and City Line service to pick up the slack along Euston Road, and transfer the Aylesbury services to London Underground.

The question of where it goes from there is more complicated, but I think via Waterloo and Kennington is an obvious option.

I've always thought that the northern Metropolitan branches would be a good fit for an Crossrail 3 route.

A tunnel portal just south of Wembley Park could take Chiltern Aylesbury services, Metropolitan Amersham and Chesham services and Metropolitan Watford services allowing a significant increase in frequency on all routes and more Uxbridge services on the remaining Metropolitan line.

My suggested stations would be at:
Wembley Park for Metropolitan and Jubilee lines;
Old Oak Common for HS2, Crossrail 1 and London Overground;
Westfield Shepherd's Bush for Westfield London, BBC Television Centre, Central Line and Hammersmith and City Line;
High Street Kensington for District and Circle lines;
Exhibition Road for Royal Albert Hall, Imperial College and the Museum district;
Victoria for District, Circle and Victoria lines;
Waterloo for Bakerloo, Northern and Jubilee lines;
Bankside for Tate Modern, the Globe, Blackfriars south entrance OSI and the City via Millennium Bridge;
Fenchurch St for the city;

You've then got various options in the east of either joining the LTS lines somewhere or heading for Canary Wharf or SE London.

You could miss out the stations at Exhibition Road and Bankside but they both fit well with an exercise someone did on London Reconnections a few years ago to map areas within Zone 1 that had poor Rail or Underground connections and high levels of travel demand.

 

[rj90]

However I see Crossrail 3 serving SW to SE. Windsor to Dartford with a core through Central London just south of the river. Putney Clapham Junction Battersea Waterloo London Bridge New Cross Lewisham.

similar could be achieved with reinstatement of the Waterloo - Waterloo east connection. Outline work a few years ago showed a connection to Waterloo East platforms wasn't feasible but it could join south of them and onto London Bridge. No idea of the capacity of these 4 lines to CHX. Would obviously be a flat junction too.

 

[Bald Rick]

similar could be achieved with reinstatement of the Waterloo - Waterloo east connection. Outline work a few years ago showed a connection to Waterloo East platforms wasn't feasible but it could join south of them and onto London Bridge. No idea of the capacity of these 4 lines to CHX. Would obviously be a flat junction too.

Sigh. This pops up every few months. Possibly earlier on this thread. It’s not do-able as has heen explained previously. Also there has not been any Outline work on it, just some kitchen table crayoning.

 

[rj90]

Sigh. This pops up every few months. Possibly earlier on this thread. It’s not do-able as has heen explained previously. Also there has not been any Outline work on it, just some kitchen table crayoning.

Absolutely agree but isn't this entire thread just crayoning?

Jacobs did a GRIP1/2 in 2009/10ish

 

[Bald Rick]

Absolutely agree but isn't this entire thread just crayoning?

Jacobs did a GRIP1/2 in 2009/10ish

First statement, agreed!

Jacobs study - not sure who they did it for, but it wasn’t for ‘the railway’.

 

[DynamicSpirit]

Wembley Park for Metropolitan and Jubilee lines;
Old Oak Common for HS2, Crossrail 1 and London Overground;
Westfield Shepherd's Bush for Westfield London, BBC Television Centre, Central Line and Hammersmith and City Line;
High Street Kensington for District and Circle lines;
Exhibition Road for Royal Albert Hall, Imperial College and the Museum district;
Victoria for District, Circle and Victoria lines;
Waterloo for Bakerloo, Northern and Jubilee lines;
Bankside for Tate Modern, the Globe, Blackfriars south entrance OSI and the City via Millennium Bridge;
Fenchurch St for the city;

You've then got various options in the east of either joining the LTS lines somewhere or heading for Canary Wharf or SE London.

You could miss out the stations at Exhibition Road and Bankside but they both fit well with an exercise someone did on London Reconnections a few years ago to map areas within Zone 1 that had poor Rail or Underground connections and high levels of travel demand.

I like this idea. It seems to me to tick quite a few boxes...

• Avoids most of the areas around the City and the West End where Bald Rick says there is physically no room to build any more lines.
• Gives quite a few places a direct connection to HS2 at Old Oak Common
• Provides an alternative route from central London for passengers connecting to HS2 at Old Oak Common - a flow which I suspect could otherwise start to overwhelm Crossrail
• Fills in a very underserved area around the museum district
• Serves the lines out of Marylebone and Fenchurch Street... surely the two London terminals with the worst connectivity into Central London. (On a slightly sad note, I suspect it would probably lead to the closure of Fenchurch Street.)

I would possibly modify the proposal to include stop at Harlesden, to connect with the Bakerloo/Euston DC lines, and the Ealing-Cricklewood line if that ever comes back into passenger service. I also wonder if you could split after Waterloo, to have some trains take over the Fenchurch Street line, while other trains tunnel to London Bridge, Surrey Quays, New Cross, Lewisham, then emerging to take over a couple of SouthEastern metro routes; that could relieve the Lewisham bottleneck and so give higher frequencies on Southeastern metro routes.

The main problem I see is that, if I recall correctly, I thought Bald Rick also mentioned Victoria and Waterloo as places where there is no room for more underground lines after CR2? (although I can't find the post so I'm hoping I haven't misquoted him).

 

[Bald Rick]

The main problem I see is that, if I recall correctly, I thought Bald Rick also mentioned Victoria and Waterloo as places where there is no room for more underground lines after CR2? (although I can't find the post so I'm hoping I haven't misquoted him).

I can’t remember either, but they are both pretty congested underground, and not just by existing transport tunnels and High Speed poo. The safeguarding for Crossrail 2 has protected a corridor at Victoria, but lots of big buildings are springing up immediately adjacent to it, and building the new entrances for it is going to be rather difficult. Finding somewhere for another tunnel and deep level station, and more importantly routes to get people between it and street level, will no doubt be a ‘challenge’.

Similar issues at Waterloo, 4 pairs of tube tunnels and lots of new buildings with deep foundations next door at Shell. I think there’s is space here though, albeit not on an E-W alignment.

 

[Mikey C]

With the chaos caused at both "terminus" ends of the Thameslink lines, I imagine Fenchurch Street and Marylebone commuters will be conscious that through running isn't always a good thing! Being relatively simple and self contained has definite advantages...

 

[AlastairFraser]

I've always thought that the northern Metropolitan branches would be a good fit for an Crossrail 3 route.

A tunnel portal just south of Wembley Park could take Chiltern Aylesbury services, Metropolitan Amersham and Chesham services and Metropolitan Watford services allowing a significant increase in frequency on all routes and more Uxbridge services on the remaining Metropolitan line.

My suggested stations would be at:
Wembley Park for Metropolitan and Jubilee lines;
Old Oak Common for HS2, Crossrail 1 and London Overground;
Westfield Shepherd's Bush for Westfield London, BBC Television Centre, Central Line and Hammersmith and City Line;
High Street Kensington for District and Circle lines;
Exhibition Road for Royal Albert Hall, Imperial College and the Museum district;
Victoria for District, Circle and Victoria lines;
Waterloo for Bakerloo, Northern and Jubilee lines;
Bankside for Tate Modern, the Globe, Blackfriars south entrance OSI and the City via Millennium Bridge;
Fenchurch St for the city; e, and

You've then got various options in the east of either joining the LTS lines somewhere or heading for Canary Wharf or SE London.
You could miss out the stations at Exhibition Road and Bankside but they both fit well with an exercise someone did on London Reconnections a few years ago to map areas within Zone 1 that had poor Rail or Underground connections and high levels of travel demand.

I like your idea up until Victoria but,after that, I would like the line to service Charing Cross, a station on Walbrook equidistant to Cannon Street and Bank, then Fenchurch Street underground to take LTS stopper metro services out to Southend Central and Pitsea via Rainham and Grays, the tunnel portal could be where Tower Gateway is today and a new Tower Hill DLR created,directly interchanging with the Tube.Fenchurch St would then just take fasts to Southend Central and Shoeburyness and it could take some fasts off the GEML via the Bow Curve to allow for a service increase on the WAML or possibly the GEML itself. The LTSR could be upgraded to 125mph for the fasts. The LO Romford to Upminister service could be extended back to Tilbury as it used to go. Marylebone could then accommodate more fast services from Birmingham and various points on the rest of the Chiltern Main Line. Potentially,if money is no object, there could be a branch continuing from Fenchurch St underground under the Thames to Bermondsey tube,South Bermondsey for the Den, New Cross(interchange with the Overground and the Goldsmiths campus),Lewisham underground station(potentially future proofed for a Bakerloo line extension), then a tunnel portal at Hither Green as another user suggested and all stops to Orpington and Sevenoaks.
The service frequency in the central core should be 20tph in each direction with 6tph Amersham to Pitsea,3tph Aylesbury to Orpington,2tph Chesham to Southend Central,4tph Watford (or potentially Watford Junction if the MLX gets back on track) to Sevenoaks, 1tph Southend Central to Fenchurch St underground,1tph Pitsea to Fenchurch St underground semi-fast,1tph Rickmansworth to Victoria semi-fast , 1tph Aylesbury to Victoria semi-fast and 1tph Sevenoaks to Victoria semi fast. Fenchurch Street underground and Victoria underground would ,of course, both have a bay platform.
Bald Rick ,I appreciate your concerns about underground space at Victoria station but maybe a Paddington-style solution is appropriate here i.e build it under Terminus Place with part of Terminus Place becoming a entrance to the station. Maybe ,if you know of any maps of underground obstructions in London, I could have a look?

 

[DynamicSpirit]

I like your idea up until Victoria but,after that, I would like the line to service Charing Cross

Err, why? If you go to Charing Cross instead of Waterloo, you lose the connection with the entire SWR service from Waterloo, and gain nothing in connectivity, since every train or tube at Charing Cross that people might want to connect with also goes to Waterloo (and if you want interchange with the District and Circle at Embankment, Altnabreac's proposal already gives that at Victoria). You do gain convenience for anyone whose final destination is within walking distance of Charing Cross, but it looks to me like you've lost far more than that. (Although maybe it's more build-able at Charing Cross with fewer conflicting underground lines?)

, a station on Walbrook equidistant to Cannon Street and Bank,

Not sure if that's physically possible around existing lines, but you do realize, that risks running the new line right through where the new escalators etc. are being built at Bank? It would basically make it part of Bank station.

then Fenchurch Street underground to take LTS stopper metro services out to Southend Central and Pitsea via Rainham and Grays, the tunnel portal could be where Tower Gateway is today and a new Tower Hill DLR created,directly interchanging with the Tube.

If you are going to close Tower Gateway (arguably not a bad thing), wouldn't it be cheaper, simpler, and more useful to most people to just run the displaced DLR trains to Bank (assuming there's capacity there? But you're not talking that many trains anyway) You can still connect with the District and Circle lines at Monument.

Fenchurch St would then just take fasts to Southend Central and Shoeburyness and it could take some fasts off the GEML via the Bow Curve to allow for a service increase on the WAML or possibly the GEML itself.

Running services via the Bow curve would cause huge capacity issues due to the conflicting moves, unless you built grade separated junctions at both ends of the curve.

The LTSR could be upgraded to 125mph for the fasts.

Uh? That's a two-track railway that already runs a fairly intensive stopping metro service. There's no way you could run 125mph trains on it without them quickly catching up with the stoppers, so you'd need to 4-track somewhere. Besides, 125mph running is usually only worth it for longer distances. Southend is only 40 miles from Fenchurch Street. If you (optimistically) got even 30 miles of that at 125mph, and ran non-stop Southend-Fenchurch Street, you'd only save 3 minutes compared to non-stop 100 mph running. And to do that, you'd have the fasts missing out a lot of stations that are just as busy (or even busier) than Southend. Plus you'd probably have years of intense disruption along the line to do the upgrades. Realistically, you'd probably want to stop even hypothetical new fast trains at least at West Ham and Basildon, and that would really make 125mph running not worth it. It would be great if a new Crossrail link allowed more trains onto that line, but you'd be far better running them as semi-fasts.

The LO Romford to Upminister service could be extended back to Tilbury as it used to go.

Meaning it would have to cross the LTSR at Upminster requiring new grade-separated junctions if you don't want to kill capacity. Would there be enough demand for through journeys to Romford to justify that expense?

Marylebone could then accommodate more fast services from Birmingham and various points on the rest of the Chiltern Main Line.

That would be great, but probably only possible with capacity upgrades along the Chiltern line out of Marylebone.

Potentially,if money is no object, there could be a branch continuing from Fenchurch St underground under the Thames to Bermondsey tube,South Bermondsey for the Den, New Cross(interchange with the Overground and the Goldsmiths campus),Lewisham underground station(potentially future proofed for a Bakerloo line extension), then a tunnel portal at Hither Green as another user suggested and all stops to Orpington and Sevenoaks.

That bit would be a good idea.