But if you shrink that diameter to what we're attempting, which is 12 feet, which is plenty to get an electric skate through, you drop the diameter by a factor of two and the cross-sectional area by a factor of four, and the tunneling cost scales with the cross-sectional area.
Dar dacă reduci diametrul, cum încercăm noi, la 4 metri, cât e suficient pentru o platformă electrică, diametrul scade de două ori iar aria secțiunii de patru ori, iar costurile tunelurilor depind de aria secțiunii.