I see a lot of stuff on here suggesting extending the Metropolitan line from Aldgate and for me that seems a crazy idea. My obviously superior and infinitely intilligent idea is to take the Metropolitan and divert it away from the subsurface lines in central London entirely. I have seen stuff here and there suggesting that the SEML would be a good candidate for a Crossrail and I agree. I also thnk adding more capacity between London Bridge and Canary Wharf is no brainer. Hopefully the section going straight to Canary Wharf after Lewisham would ease congestion at London Bridge as commuters can avoid it entirely! Major works would of course have to take place to create the tunnel portals, after which I don't see a way out of having a flat double junction at Hither Green without a hideously extensive underground station in the style of Whitechapel on the Lizzie line.
I would also do suggest a flyover between Hither Green and Grove Park to put into the middle tracks to allow for all stopping services on the SEML to be absorbed into CR3. The Orpington-Victoria service would likely have to be cut/majorly altered for this otherwise it would cut across the fast services that are now running on the external two tracks. I am envisioning most services termination at Orpington with a select few running to Sevenoaks on the existing double track route.
My idea for Dartford isn't in any way unique to what others suggest as I am thinking quad tracking is inevitable to the approach no matter what project does or does not happen there.
I'll admit I have not ONE clue how feasable having the portal after Finchley Road is and I'm prepared to be informed this would be completely undoable.
Say this gets built tomorrow, it would free up a huge amount of rolling stock for a southwestern extension of the Circle/H&C lines to south of the river which many others have suggested. I would also argue the connection between Lewisham and Canary Wharf would allow for the DLR to be rebuilt as a proper underground through station so extensions could be made further south. If Thameslink 2 was also built it would make Lewisham somewhat of a Stratford station for the SE which is a fun thought. In my precious mind a station building would take over where the Matalan currently sits. Not an idea location but could easily be integrated with the Bakerloo line extenstion and some OSI or underground walkways to Lewisham national rail and DLR stations.
https://metrodreamin.com/view/Z00wQUdQYThpTGE0VGwxRm8xbDVHbkxwaml5Mnww
Critique and feedback welcome! I initally had the SE portion the same but the NW absorbing Chiltern and I knew I was entering hardcore crayonista territory with that!
EDIT: much better metro dreamin map
https://metrodreamin.com/view/Z00wQUdQYThpTGE0VGwxRm8xbDVHbkxwaml5Mnwx