Manhole Covers

Cecil's Columns/Staff Reports
1

Manhole covers are often round as it stops them being accidentaly dropped down the manhole. Period.

Many round covers have a notch in one side that fits over a protruding piece in the rim, so the reason given for easy replacement does not stand up.

Covers in Europe sometimes consist of two right-angled triangles attached by a loose bolt in the middle. These 2 pieces together form a square. This stops rattling as traffic passes over loose covers, as teh triangle will sit firmly on a slightly uneven rim, unlike a square or circle, which will rock in the same situation.

For anyone who has tried, a full-strength cover, intended for use in heavy traffic situations, is quite heavy and it is easy to drop down the manhole. Nothing to do with being a Sanitation moron, rather to do with being a lightly-muscled engineer!:slight_smile:

2

Article referred to:
Why are manhole covers round?

3

I have another thought about the shape of manhole covers.

I believe that the round shape, besides not falling into the whole, also is the best one for actual humans to access, with their bodies (I’ve actually been done in some!). The human body is more round than square (and much more round than triangular).

The shape also generally provides the most useable area for access (unless one is putting square hoses down a square manhole) – the corner areas would be “wasted” in a sense (and the covers, in such a case, would be unecessarily heavy/massive).