ततः संधिच्छेदखातसुरुङ्गाभिरपगच्छेत् ॥ कZ_०७.१७.४८ ॥
tataḥ saṃdhiccheda-khāta-suruṅgābhir apagacchet
Then he should depart by means of breaches in walls, ditches, or tunnels.
They represent layered escape infrastructure: improvised exits (breach), terrain masking (ditch), and preplanned covert corridors (tunnel).
States should anticipate and control subterranean/structural escape vectors around sensitive sites (forts, residences, prisons).