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Almost every tunnel has a lining that makes widening prohibitive. Which is why the London Underground is forever stuck with small tunnels on the original lines.
by NeedMoreTea 7y ago
Almost every tunnel has a lining that makes widening prohibitive. Which is why the London Underground is forever stuck with small tunnels on the original lines.
- Retric 7y agoA larger issue is the underground is in use forcing you to do something like: www.rocksoil.com/pdf/233_r.pdf That and the cost vs benefit is not considered worth it.