मुखसमः संक्रमः संहार्यो भूमिमयो वा निरुदके ॥ कZ_०२.३.३० ॥
mukhasamaḥ saṃkramaḥ saṃhāryo bhūmimayo vā nirudake
The approach/passage (saṃkrama) should be aligned with the gate-front (mukha-sama); it should be removable (saṃhārya), or else made of earth (bhūmimaya) where there is no water (nirudaka).
It allows the defender to deny entry quickly during attack, converting access routes into obstacles.