Methodology
The list of largest clear span structures
needs a litte additional explanation:
Qualifying structures
In the context of this site, the size of a dome is taken to
refer to the diameter of the largest
horizontal circle that will completely fit
inside the dome.
To qualify for the list:
- Structures must be fully covered, or capable of being
fully covered. A few Small holes in the roof are
permitted - but large holes - or large
numbers of holes that let in wind and rain -
are not.
- Structures must have a clear span of 100m or greater.
Air supported structures are permitted. Internal structures
that reach up as far as the roof are permitted only
if their structural element is very minor.
One example of a structure that does not qualify for this
list, is the Commerzbank Arena. This can reach
about 99% coverage when closed - but it appears that rain
cannot currently be effectively eliminated from the
interior.
Another structure that fails to qualify is the Arecibo
Observatory. At 305m in diameter, this might
be the largest clear-span structure in the world. However,
currently the fabric of the roof is held down with numerous
cables - and the fabric itself is porus - and lets in the
rain - and so this structure doesn't currently appear on
this list.
Accuracy
All figures are approximate - and may be subject to revision
as more accurate information comes to light.
I've made an effort to calculate the clear span of The
Millennium Dome at the point where the distance between
the towers is the largest.
Corrections would be gratefully received. They may be
submitted to the maintainer of this page
here.
Alternative approaches
Instead of taking the size of a structure to represent a
measure of the associated clear span, it is also possible to
consider a measure of how much space is protected from the
elements.
Such a list would look a little different:
The Muna bulk reservoir - at 340m in diameter - would be number one.
The Millennium dome at 320m in diameter - would be number two.
Structures such as the Haj Terminal might get into the list.
This approach was rejected on the grounds that the clear
span was a more significant metric.
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