Do You Know Why a Manhole is Circular in Shape


What is a Manhole ?

It is a small covered opening in a paved area allowing access beneath, especially one leading to a sewer.

You may Give the following reasons :

  1. It would be easy to clean as there will be no corners where the dirt can accumulate
  2. It must be to ensure the safety of the person going inside the manhole. If the manhole is rectangular or square shaped then there are chances that the person will hurt himself with the sharp corners of the manhole

The above reasons are okay but not the prime reasons for a circular design. The main reason is –

Because there are no angles for alignment, the round shape makes these heavy covers easier to put back on once they’re taken off. Round covers are also easier to manufacture.


But the main reason manhole covers are round is so they won’t accidentally fall into the manhole itself. With a round cover, no matter how you hold it, you can’t shove it in. It just won’t go. If it were square, a prankster could hold the cover diagonally over the hole and drop it in, to be followed by who knows how many scooters and pedestrians. 

Manholes are designed circular in shape to avoid this unwanted fall

This is a common interview question


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