
Compact Tunnel Boring Machines Are Major Players in North America - curtis
http://trenchlessonline.com/compact-tunnel-boring-machines-major-players-north-america/
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curtis
I have been wondering if running smaller trains through smaller tunnels might
be a more cost-effective way of implementing mass transit, at least in some
cases. Clearly the tunneling technology exists. I'm still looking for
information about the cost-per-mile, though.

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jaclaz
The subways of Tolouse (France) and Turin (Italy), and several others, are
based on that concept, JFYI:
[https://en.wikipedia.org/wiki/Turin_Metro](https://en.wikipedia.org/wiki/Turin_Metro)
[https://en.wikipedia.org/wiki/Toulouse_Metro](https://en.wikipedia.org/wiki/Toulouse_Metro)
[https://en.wikipedia.org/wiki/Toulouse_Metro#Technology](https://en.wikipedia.org/wiki/Toulouse_Metro#Technology)
They use a VAL kind of train:
[https://en.wikipedia.org/wiki/Véhicule_Automatique_Léger](https://en.wikipedia.org/wiki/Véhicule_Automatique_Léger)
The excavation diameter for the tunnel is (one track) typically 5.3 m and 7.7
m (two tracks), the net diameter inside is smaller of course, depending on the
thickness of the concrete lining, usually 4.5 and 6.7 m, respectively. Cars
are 2.06 m wide and of course tall enough for a standing person
(+undercarriage) 3.25 m, there is not much you can do to further reduce their
size.

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Gravityloss
I think in addition to the practical person x distance / time etc, we should
look at transportation systems as part of life, culture and the city.
Alternatives like trams might have a lot more other value to people.

