Manhole covers are round if they cover a pipe and square if they cover a brick built manhole.
Your note about them not falling in makes me wonder if Google had a different answer?
Your note about them not falling in makes me wonder if Google had a different answer?
This is inaccurate as a generalization - in the three jurisdictions I've worked in, they're round if they're newer than ~1990, and mix of round and square (or two triangles that go together to make a square) if they're older than that. The frame and cover are replaced independently from the MH structure itself so the cover doesn't tell you anything about the makeup of the structure.
Edit: for example https://maps.app.goo.gl/m8rR4vrPHBPTyXxo9
It's the kind of question that's asked in interviews because it has several answers and a good candidate should be able to think it through and suggest a reasonable number of them and demonstrate their ability to creatively think through a problem. That round covers can't fall in seems one of the simplest and most important, given that a cover that falls in could kill or seriously injure a worker.
https://www.livescience.com/32441-why-are-manhole-covers-rou...