There are many reasons,
-> Very easy to manufacture compare to other shapes.
-> If water is flowing over to it , then it is capable of redirecting the water into tank or canal itself.
-> While closing the cap of manhole, just lift the cap perpendicular to the earth and turn it diagonal and leave, certainly it will not go in, but in other shapes it is possible.
-> Very easy to manufacture compare to other shapes.
-> If water is flowing over to it , then it is capable of redirecting the water into tank or canal itself.
-> While closing the cap of manhole, just lift the cap perpendicular to the earth and turn it diagonal and leave, certainly it will not go in, but in other shapes it is possible.
