The round manhole cover allows for easy installation and transport as well as prevents the risk of pitfall.
The round cover is easier to install into the manhole.
Why are manhole covers usually round? Manhole covers are quite heavy, so their round shape allows them to be transported easily from one place to another by rolling them around.
In addition, the round cover is also easier to install into the manhole. While the square or triangular cap needs to align the corners and edges correctly.
Besides, the edge of the manhole often has a small groove, this groove makes the crater always smaller than its cover, preventing the lid from falling into the pit during installation. Meanwhile, square or rectangular covers can still fall into the manhole. Do you know why?
That’s because the side of a square or rectangle is always smaller than their diagonal. The round manhole cover never falls through the hole because no matter how you rotate it, the manhole cover is always wider than the crater.