look here for a laugh

I love the idea that tunnels can be widened in overnight possessions...
So signalling and communications team come and get their cabling out the way... Lift the tracks... Remove the old tunnel lining... widen the tunnel... put in new tunnel lining... shore up joins between widened and unwidened sections... relay tracks... sort out signalling/comms infrastructure... have all the work thoroughly inspected... get all the spoil and equipment back out... and let the nightly maintenance carry on as usual...
Course they can do all that in the 4 hours current is off
They had the right idea with deep level tubes... I'm sure it's still cheaper and easier to dig new tube tunnels than do this level of work to existing ones. With little disruption to existing services. It's just political will and financial backing that's lacking

Granted public transport projects in London seem to take for ever to get off the drawing board, but one must have a sense of realism too. Its good to dream, and its even better to try to make them come to fruition, but one cannot ignor certain facts about lack of money, ageing infrastructure, high expectations and low levels of room for error.
The time will come when things will need to be renewed, reengineerd, replaced and alterd, and I'm sure we can all think of twenty things with the tube alone that would benefit London; but we must remember not to become overly frustrated at things impractical to achieve instantly, and not to forget that progress takes time.

Having said all that, I personally still recon London will be in a pickle transportwise by the time 2020 comes about!

Actually it is quite feasible to widen tunnels in normal engineering hours, it was done at Angel when the new station was being constructed and it was done between Old St. and Moorgate in the mid 1990s. Of course in theory and in practise digging a shaft down to an existing tunnel and building a new one around it is nothing unusual and in general terms it has little effect on the working railway. Whilst that is happening cables will already be being diverted etc within the existing tunnels and other works as necessary.
It is all tried and tested but it doesn't happen in a night, it takes months and months. However, far less is done in real terms per shift in today's H&S conscious world despite the automation of many tasks and state of the art machinery. When I started on the Underground the stage one Jubilee line was nearing completion and the amount of work done in a nightshift back than would amaze many today. I remember my very first night at Baker Street running lead cables between St. John's Wood and Baker Street part of an installation gang of eight Whitechapel signal staff. There were gangs from Earls Court, Baker Street and Wembley Park signals working there too running cables, installing equipment, laying points and wiring the IMR and relay rooms. The platforms were as busy as in the rush hour with Italian floor tilers, plasterers, wall tilers, electricians and others and billposters too, people in all the tunnels, and in every nook and cranny including the vent shaft, the inverts and the escalator machine chambers. All protected in a possession taken within minutes of the discharge of traction but it just doesn't work like that any more.
Protection alone is a major undertaking these days, it is simply not possible to do today what was done 30 years ago or indeed 80 years ago.
I spent some time at London Bridge diverting train radio and other comms circuits and the working conditions were horrendous with bulldozers running up and down the tunnels, the track having been lifted, great piles of spoil everywhere and everything removed ready for enlargement and interception.

It could well be cheaper to build from scratch but interchange is what it's all about and that is where the money is spent because it has to be.

Noooo! Please don't widen the tunnels. Then we'd have bland normal sized trains, the Tube train is as Londoney as Double-decker buses!