Why are manhole covers round?
Sigiloso
There are atleast three reasons manhole covers are round. 1. A round cover can not fall into the hole. 2. A heavy round cover can be easily moved by rolling it on its edge. 3. A round cover can be easily centered and aligned when being replaced. I'm certain there would be other possible answers, such as its easier for a person entering the manhole at any angle with round hole and cover....etc etc