On: You don't bury survivors - transcript of an interv...

[Super_Jambo]

aha, see I was wondering why it wouldn't be triangular, not only would the covers not fall in they also couldn't roll away.

Joke is that in the UK some manhole covers (bt?) are more or less triangular.

[afterburner → Super_Jambo]

Are you assuming having covers that can't roll is a good thing? Being able to roll them might be an advantage in mobility.

[khafra → Super_Jambo]

A cover in the shape of a reuleaux triangle still wouldn't fall into the shaft, but also wouldn't roll away--it would have constant width, but its center of mass would move up and down while rolling. Apparently the UK has superior civil engineers.

[vl → Super_Jambo]

In modern US cities there are a lot of different manholes, mostly round and rectangular - some shafts don't go deep, so there is no need to make shaft round.

I wonder what kind of shaft is under triangular cover, why would someone build triangular shaft? :)