And looking at tunneling technology, it turns out that in order to make a tunnel, you have to -- In order to seal against the water table, you've got to typically design a tunnel wall to be good to about five or six atmospheres.
Promatrajući tehnologiju tunela, ispada da, kako bi se napravio tunel, trebate -- Kako biste se osigurali od podzemnih voda, trebate sagraditi zid koji može izdržati pritisak od oko pet ili šest atmosfera.