charles Wrote in message:
In article ,
Max Demian wrote:
On 21/03/2018 23:10, Jim K wrote:
Max Demian Wrote in message:
On 21/03/2018 20:22, Jim K wrote:
Johnny B Good Wrote in message:

It was not I who was obsessed with bridges needing to be "flat",
it was you. I think you are conflating Brian's mention about
'flatness' and curvature of the Earth corrections with my not being
able to find a curvature of the earth divergence figure for the
Severn bridge to compare against the figure that Tim+ had found for
the Humber bridge. I made no mention of 'flatness' until you
introduced it into this sub-thread.

--
Johnny B Good


Oh dear. Put very simply, if one wasn't trying to build
something flat, why would one be bothered with calculations to
the mm to allow for curvature of the earth ? !

To ensure that it's curved to the right degree?

Such as a.........?
(not a bridge shurely, if anything they are more likely to be hump
backed...)

A long, perfectly flat bridge deck would effectively dip in the middle
from a gravity POV. You would probably want it to follow the curvature
of the Earth.

Indeed, if you drive over one of these long bridges you are going "up hill"
to the centre and then down again on the other side.

--
from KT24 in Surrey, England


You can sometimes see ships going underneath too...

--
Jim K


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