Question

the reason by mainhole covers are round?

Answer 1

A round manhole cover cannot fall through its circular opening, whereas a square manhole cover could fall in if it were inserted diagonally in the hole. Circular covers don't need to be rotated or precisely aligned when placing them on the opening. Around manhole cover is easily moved and rolled.

Answer 2

A round manhole cover cannot fall through its circular opening, whereas a squaremanhole cover could fall in if it were inserted diagonally in the hole. Circular coversdon't need to be rotated or precisely aligned when placing them on the opening. Around manhole cover is easily moved and rolled.