In message
-sept
ember.org, at 08:56:48 on Sun, 26 Mar 2017, Recliner
remarked:

One limiting factor on tunnel size is that they have to bear the weight of
575 tonne A380s a few metres above.

You've not seen the highway tunnels with their portals only metres away
from the runways at Schiphol? https://goo.gl/maps/K5NbbmjqqL42

Seen and travelled through them.

Good. You'll therefore note that much wider and much shallower tunnels
don't collapse under the weight of huge planes.
--
Roland Perry