Why are manhole covers round and not square or rectangular?

Question

Why are manhole covers round and not square or rectangular?

Answer 1

There are a whole slew of reasons why manhole covers are round. The covers are made of cast iron and so are very heavy. By making them round they can be rolled rather than carried from place to place on the job. The tunnels leading to the covers are almost always round, for structural as well as ease of digging reasons. Since the tunnels are round it made sense to make the cover round. If the covers were square, rectangular, etc. the cover would have to be in a particular orientation in order to fit the hole. In addition the cover could fall into the hole if it were square or rectangular (or any other shape than round). Finally it may boil down to "that's the way they always been made" kind of thinking. Someone started making them round when they first started and everyone else followed

Answer 2

Why Are Manhole Covers Round

Answer 3

to protect it from falling down the manhole. it can easily cover the manhole, no edges to fit through....

Answer 4

circle has maximum surface area compare to all shapes. so, by using circular manhole, the material used to manufacture mahole can be reduced.

Answer 5

Square would fall threw, round will not

Answer 6

Round ones are easier to maneuver and don't have dangerous sharp corners.

Answer 7

Squares and rectangles would fall in if they angled just so. Round ones won't.

Answer 8

because circles are awesome! they look better!