Tunnelling to begin on the extension in March

[Jim]

link

The tunnel boring machines look massive a lot bigger than a standard tube tunnel size, I guess the tunnels will have walkways in them like most modern underground systems in the world.

[dave1]

I think you are right as they seem to put in walkways for detrainment reasons. I am sure other tunnels are wider than the original tubes and they had what looked like a walkway but was a baffle full of asbestos.