Problems:
1) HS2 will dump loads of extra people into Euston with insufficient capacity to get rid of them.
2) Crossrail 2 is expensive, and despite politicking from Boris, it ain't going to happen.
3) The c2c, the only main railway with no Zone 1 tube connection, has been ignored by the Crossrail project, with the Abbey Wood branch passing under the platforms of Limehouse station with no interchange, and the Shenfield branch running beneath the c2c for 1 kilometre with no station on either line.
4) The H&C has lost its raison d'etre, with a quicker route between Whitechapel, Liverpool Street, Farringdon and Paddington now available. When HS2 connects Old Oak to Euston, most traffic from Paddington to Euston and Kings Cross will also disappear, so the first part of the Underground is becoming somewhat redundant in its original (and current) form.
5) The Amersham line having trains from Baker Street and Marylebone is a bit crap - they are too close to serve different parts of London, but too far apart to enable you to enjoy the combined frequency.
6) The capacity through Euston Square is constrained by all the flat junctions on the Circle Line, and also by the alternating 7- and 8-car trains.
Solution:
The line through Euston Square needs to be all 8-car and have no flat junctions.
Baker Street Circle platforms should become a 2-platform terminus for trains from Hammersmith, with trains from Wimbledon and a (renamed) Circle Line from Gloucester Road etc also being extended there from Edgware Road. The current Metropolitan Baker Street terminators would be extended through Euston Square. The line from Aylesbury to Amersham would be (overhead) electrified and that part of the Chiltern service would become part of the Metropolitan Line, remaining on the Met fast tracks past Harrow to Euston Square and beyond. The Chiltern line from Harrow to Neasden would become disused, and this would probably allow more trains to run into Marylebone from the South Ruislip direction, for which I believe there is demand. The current hourly capacity through Harrow seems to be up to 22 8-car Mets (some to Baker Street, some to Aldgate) + up to 5 5-car Chilterns. When all of these are made 8-car and extended through Euston Square, there should be room for more.
The abandonment of the Chiltern Harrow Line where it crosses the WCML would allow the Met tracks to be slewed southward, allowing a pair of curves to branch off the outside and descend and curve to a flat junction with the Slow Lines on the east side of the WCML. In this way some of the WCML Slow Line service could become part of the Metropolitan line, giving noticeably slower journeys to Euston but faster journeys to Baker Street, Kings Cross etc. This would lessen the number of people changing at Euston itself. (I don't know enough about freight on the WCML to know if this flat junction is feasible.)
East of Euston Square, the Metropolitan line would take over the C2C. Aldgate and Aldgate East stations would be closed, and the Met line would descend within the footprint of Aldgate station to a new Aldgate interchange roughly where the bus station is, with new Met platforms beneath and just east of new District platforms on the existing alignment. After a small amount of demolition, the Met would curve eastward and break the surface at the corner of Pinchin Street and Back Church Lane, and then rise to join the LTS viaduct at Cannon Street Road to take over the entire LTS service. I believe the tracks into Fenchurch Street currently carry about 192 carriages per hour per direction and the tracks through Barbican currently carry about 200 carriages per hour per direction, so the capacities match well. The Circle service west of Tower Hill and the H&C service east of Aldgate East would be joined to give a new Loop service from Barking to Baker Street via Gloucester Road.
Any additional Met trains could be sent to Barking Riverside, which would be extended to 8 carriages: the Overground service would revert to terminating at platform 1 at Barking. Replacement of a smaller number of 12-carriage trains on the c2c with a larger number of 8-carriage trains would probably overload the flat junction at Barking, requiring grade separation - this can probably be done using existing bridges with rearranged tracks.
Fenchurch Street could be closed and sold, or could replace Tower Gateway as a prettier DLR terminus which is nearer to Tower Hill tube. (Network Rail's 2020 Essex Thameside Study discussed closing Fenchurch Street station and relocating it to Tower Gateway.)
The changeover between 4th rail and overhead might occur at new Shadwell platforms, and also at Amersham (and maybe at the new Kenton curve). The extended Metropolitan line might be branded as another line of the Crossrail network, since Shoeburyness and Aylesbury are the same distance from London as Reading, although Underground service at Shoeburyness and Aylesbury does have a historical precedent.
1) HS2 will dump loads of extra people into Euston with insufficient capacity to get rid of them.
2) Crossrail 2 is expensive, and despite politicking from Boris, it ain't going to happen.
3) The c2c, the only main railway with no Zone 1 tube connection, has been ignored by the Crossrail project, with the Abbey Wood branch passing under the platforms of Limehouse station with no interchange, and the Shenfield branch running beneath the c2c for 1 kilometre with no station on either line.
4) The H&C has lost its raison d'etre, with a quicker route between Whitechapel, Liverpool Street, Farringdon and Paddington now available. When HS2 connects Old Oak to Euston, most traffic from Paddington to Euston and Kings Cross will also disappear, so the first part of the Underground is becoming somewhat redundant in its original (and current) form.
5) The Amersham line having trains from Baker Street and Marylebone is a bit crap - they are too close to serve different parts of London, but too far apart to enable you to enjoy the combined frequency.
6) The capacity through Euston Square is constrained by all the flat junctions on the Circle Line, and also by the alternating 7- and 8-car trains.
Solution:
The line through Euston Square needs to be all 8-car and have no flat junctions.
Baker Street Circle platforms should become a 2-platform terminus for trains from Hammersmith, with trains from Wimbledon and a (renamed) Circle Line from Gloucester Road etc also being extended there from Edgware Road. The current Metropolitan Baker Street terminators would be extended through Euston Square. The line from Aylesbury to Amersham would be (overhead) electrified and that part of the Chiltern service would become part of the Metropolitan Line, remaining on the Met fast tracks past Harrow to Euston Square and beyond. The Chiltern line from Harrow to Neasden would become disused, and this would probably allow more trains to run into Marylebone from the South Ruislip direction, for which I believe there is demand. The current hourly capacity through Harrow seems to be up to 22 8-car Mets (some to Baker Street, some to Aldgate) + up to 5 5-car Chilterns. When all of these are made 8-car and extended through Euston Square, there should be room for more.
The abandonment of the Chiltern Harrow Line where it crosses the WCML would allow the Met tracks to be slewed southward, allowing a pair of curves to branch off the outside and descend and curve to a flat junction with the Slow Lines on the east side of the WCML. In this way some of the WCML Slow Line service could become part of the Metropolitan line, giving noticeably slower journeys to Euston but faster journeys to Baker Street, Kings Cross etc. This would lessen the number of people changing at Euston itself. (I don't know enough about freight on the WCML to know if this flat junction is feasible.)
East of Euston Square, the Metropolitan line would take over the C2C. Aldgate and Aldgate East stations would be closed, and the Met line would descend within the footprint of Aldgate station to a new Aldgate interchange roughly where the bus station is, with new Met platforms beneath and just east of new District platforms on the existing alignment. After a small amount of demolition, the Met would curve eastward and break the surface at the corner of Pinchin Street and Back Church Lane, and then rise to join the LTS viaduct at Cannon Street Road to take over the entire LTS service. I believe the tracks into Fenchurch Street currently carry about 192 carriages per hour per direction and the tracks through Barbican currently carry about 200 carriages per hour per direction, so the capacities match well. The Circle service west of Tower Hill and the H&C service east of Aldgate East would be joined to give a new Loop service from Barking to Baker Street via Gloucester Road.
Any additional Met trains could be sent to Barking Riverside, which would be extended to 8 carriages: the Overground service would revert to terminating at platform 1 at Barking. Replacement of a smaller number of 12-carriage trains on the c2c with a larger number of 8-carriage trains would probably overload the flat junction at Barking, requiring grade separation - this can probably be done using existing bridges with rearranged tracks.
Fenchurch Street could be closed and sold, or could replace Tower Gateway as a prettier DLR terminus which is nearer to Tower Hill tube. (Network Rail's 2020 Essex Thameside Study discussed closing Fenchurch Street station and relocating it to Tower Gateway.)
The changeover between 4th rail and overhead might occur at new Shadwell platforms, and also at Amersham (and maybe at the new Kenton curve). The extended Metropolitan line might be branded as another line of the Crossrail network, since Shoeburyness and Aylesbury are the same distance from London as Reading, although Underground service at Shoeburyness and Aylesbury does have a historical precedent.
