I know that they are round because the lid won't fall in. A square on won't work because at a diagonal, the lid can fall, but is the same true for a triangle? What about other shapes?
2006-11-30 05:30:53 · 11 answers · asked by Anonymous in Education & Reference ➔ Trivia
They are designed so a person can go down under ground. To accomodate a person the triangle would have to be large and there would be wasted space in the corners. A circle accomodates our bodies nicely.
2006-11-30 05:34:29 · answer #1 · answered by Red Wing 3 · 3⤊ 0⤋
the triangle would be pretty big - a circle the same size as a manhole would have to "fit inside", so there's more expense and the triangle would be heavier to lift or slide out of the hole.
when a worker needs access, i would think a circular shape is easier to "roll" out of the hole. with a triangle you would have to "flip" it or completely lift it enough to get enough of the edge on the pavement to slide it.
actually, i think i've seen them used for some meter boxes where you only have to look in, so they were pretty small.
and the asker is right - a triangle lid wouldn't fall in. it would only fall in if it were a 2D object or if it wasn't a perfect triangle. it's thickness is what would keep it from falling in.
2006-11-30 05:38:11 · answer #2 · answered by adrienne 2 · 1⤊ 0⤋
While it makes sense that it would save space and time, manholes have allways been round. (The greeks had the). Simple reason, the circle is the only shape that when cut out of something it can' fall into it's own hole. Triangles, sqares, octogons, etc can be tilted to fit into the hole they where cut from.
2006-11-30 14:14:28 · answer #3 · answered by mors11284 2 · 0⤊ 0⤋
the significant objective is for the reality that if the manhole replace into as quickly as sq. (or oblong or triangular), it could be plausible to have the canopy at an attitude and for this reason drop it in a fashion such that the canopy could plummet down the manhole, which might very injure or kill somebody in that's technique down, or for the worries of those development the suggestions-set, a falling manhole duvet could very actual harm the piping and wiring this is residing in the below grade ductwork. yet another purpose could desire to be that it could make it so much less complicated to duvet the manhole, as a around manhole duvet is non-directional, meaning that it could desire to be seated merely as reliable at any diploma of rotation. alongside with the above, a curved floor is extra effectual ideal for dispensing the forces of passing automobiles etc with a minimum of stress accumulation. (a reliable occasion of the worst case subject of stress accumulation could additionally be seen in the study related to the 1954 DeHaviland Comet crash off of Italy). stress accumulation could make the main a quantity of defects in the supplies used, and reason some nasty issues. for this reason, a around duvet (and hollow) fairly does now no longer have any sharp edges, which makes it safer to regulate.
2016-12-29 17:23:10 · answer #4 · answered by Anonymous · 0⤊ 0⤋
Manhole covers are round because it makes the smallest (and cheapest/lightest) cover ... for the round tunnel. Its the tunnel shape that determines the cover's shape, in this case.
2006-11-30 05:39:53 · answer #5 · answered by kheserthorpe 7 · 1⤊ 0⤋
A triangle could fall through as well.
2006-11-30 05:39:39 · answer #6 · answered by Kacky 7 · 0⤊ 1⤋
Even a triangle can fall in.
2006-11-30 10:46:02 · answer #7 · answered by Mayur 2 · 0⤊ 1⤋
Have You Ever Seen a Man With a " Triangular HOLE"
2006-11-30 05:39:24 · answer #8 · answered by rhijoa 2 · 0⤊ 2⤋
How about heart shaped? Nah. That wouldn't work.
2006-11-30 05:34:42 · answer #9 · answered by jare bare 6 · 0⤊ 2⤋
b/c they will fall in the hole. that's why they are a circle
2006-11-30 05:34:19 · answer #10 · answered by Aztec 1 · 0⤊ 3⤋