Have you ever wondered why manholes are shaped the way they are? Why aren’t they square or rectangular? What’s the reason why manhole covers are round? (This sounds like a random, why-are-they-asking-me-this job interview question, doesn’t it?)
At Rogue Valley Precast, we create precast molds that are used for manholes, so we’re keenly aware of the importance of manhole covers.
#1: The circular shape provides protection for the manhole.
A manhole leads to tunnels and canals below ground that are very deep. Think about how hard it would be to retrieve something that falls through a manhole. It might even be impossible.
To protect the manhole and anything that might fall into it, the round cover is best. That’s because circular covers or round covers cannot fall into the hole. Other shapes, such as a square cover, could possibly be forced down into the manhole (even if they have to be inserted diagonally) leaving the area exposed.
#2: Round covers are easier to lift.
Manhole covers are generally very heavy, ranging from 200 pounds to 300 pounds. To make them easier to move, the round shape is easier. That’s because it can be rolled rather than lifted.
#3: Circular shapes provide better seals.
When it comes to securing a manhole, it is very important that it is sealed properly. If it isn’t, it could cause vehicle damage as cars pass over it. If someone walks over it and it is loose, they could trip or even fall in.
Circular manhole covers seal the best on the small lip that sits around the top of the manhole, ensuring that passersby are kept safe, and the manhole stays secure.
#4: It’s more economical.
Round covers don’t use as many materials. Therefore, they are easier to produce and are less expensive.
So what’s the reason why manhole covers are round? Interesting question. Above are just a few of the intriguing reasons why.
Our experts at Rogue Valley Precast understand how important manholes are to living life in a city or suburb. We do a lot of work in the public infrastructure realm, assisting our colleagues in the construction and development industries with a wide variety of precast concrete products, including manholes.
Call or visit us today to learn more about how we can help with your precast concrete product needs.