3 ms·
Firstly most of the London Underground was built cut-and-cover which is no longer practical in modern cities. Secondly, this will be much smaller than even the
by gok 8y ago
Firstly most of the London Underground was built cut-and-cover which is no longer practical in modern cities. Secondly, this will be much smaller than even the Tube. Crossrail’s tunnels will be about 6 meters, most existing are more like 4. BoringCo is talking about something like 2 meters. Note that a 2m tunnel requires excavating 4x less earth than a 4m tunnel and 9x less than a 6m tunnel.
Most modern tunnels built for existing transit systems are built to fit existing rolling stock, so the idea of smaller tunnels gets ruled out early on. In the past, smaller tunnels were used. In fact, one of the most extensive small tunnel transit networks was in Chicago: https://en.m.wikipedia.org/wiki/Chicago_Tunnel_Company https://en.m.wikipedia.org/wiki/Chicago_Tunnel_Company
- Symbiote 8y ago> Firstly most of the London Underground was built cut-and-cover The small-diameter tunnels we're talking about were built with a tunnel shield, which is the hand-operated predecessor to the TBM. https://en.wikipedia.org/wiki/History_of_the_London_Underground#Electric_underground_railways_(1900%E2%80%931908) https://en.wikipedia.org/wiki/History_of_the_London_Undergro...
- isostatic 8y agoMost of the London Underground is above ground. Of that underground, I Elise the majority is the deep tube bored lines (pic, jubilee, bakerloo, central, northern) rather than pretty much just the circle that's cut and cover.
- spiralx 8y ago> Most of the London Underground is above ground. Technically true, it's 45% that's underground, which includes 32km of cut-and-cover lines and 150km of tunnels out of the 402km total.