Question: Why are manholes round? Why can’t they be squares, or rectangles, or heart-shaped? We’ll answer that in a bit, but first, another manhole trivia! If you travel to Japan, chances are you’ll come across a manhole like no other – the artistic manhole. 95% of Japan’s 1,780 municipalities you will find these public artworks.
Each city and town has a unique set of manhole covers that represents their culture. Some of these artworks depict architectural heritage sites, scenes from daily life, cultural animals and flowers, and many more. For some, manhole spotting and photography has become a hobby. Also, these manhole covers are carved from master plates located in a central library and are forged in Nagashima Foundry.
Now, to answer the question, “Why are manholes round?” The answers are quite simple. They are round because 1) since there are no angles for alignment, it’s easier to put these heavy covers back on 2) round covers are easier to manufacture 3) with a round cover, it’s impossible for it to fall in the hole it is covering.
Though personally, if I were a sewer maintenance worker, I’d prefer the heart-shaped cover. Nothing’s better than seeing a heart-shaped manhole cover right before you dive into the deep, dark abyss of the sewer, right?