4 ms·In London they are digging a 32km tunnel using TBM's to carry 400kV AC lines.by 7952 14y agoIn London they are digging a 32km tunnel using TBM's to carry 400kV AC lines.Swannie 14y agoThey are? Cool, I've not heard of this one. Any references?7952 14y agohttp://www.londonpowertunnels.co.uk/ http://www.londonpowertunnels.co.uk/