When the London Eye opened in 2000 it was intended to be a temporary attraction - but
it proved so popular that it became a permanent fixture of the skyline,
making towering observation wheels the new must-have landmark of the new millennium.
Since then, more than 18 giant observation wheels have been built
around the world - but despite the title of “world’s tallest” changing hands three times,
the actual height of the tallest observation wheel has only risen from 135-metres in 2000,
to 169-metres in 2014 when Las Vegas completed the High Roller.
Echoing the extreme height increase that saw it claim the title of World’s Tallest Building,
Dubai’s latest record-breaking attraction takes engineering to the limits,
with an observation wheel that’s nearly double the height of the London Eye.
Located just off the coast of Dubai Marina on the man-made, Bluewater’s Island, Ain
Dubai - or the Eye of Dubai - is now officially the world’s tallest and largest observation
wheel - standing over 250 metres tall and with a capacity of 1,750 passengers at any one time.
82 metres taller than its predecessor, Ain Dubai represents the single greatest increase in height
for this type of structure - something that could have only been achieved in a place like Dubai.
So, in terms of structural challenges, I don't think you compare the Ain Dubai with
any other wheels, and I probably would say that just because it is by far the largest.
Without getting too technical a lot of the stress relationships are a squared factor
so it's not just a linear proportion, so it gets twice as big the stresses get twice as big
it's actually a squared relationship and we were pushing the bounds of engineering
on this wheel probably more than any other wheel has done before.
Originally set to stand 210 metres tall when it was first proposed back in 2013
the wheel was redesigned and scaled up to a size that would require
33% more steel than was used in the Eiffel Tower.
Now an artificial island - which is essentially compacted sand - might
not seem like the best place to build something of this magnitude
but the reclaimed land itself doesn't actually bear much of the wheel's weight at all.
Drilled to a depth of 35 metres, Ain Dubai’s foundation piles extend
five metres into solid bedrock, completely bypassing the reclaimed land - Bluewater’s
Island only provides lateral support for the structure.
With a solid base to build on, the hard work really began with the four legs - each
126-metres in length, that’s just nine-metres shorter than the London Eye’s overall height.
The biggest challenge for engineers didn't actually come from the leg’s size,
but from keeping them standing at a precise angle while the hub and spindle
were fitted - they tie everything together and make the structure self-supporting.
There was approximately four weeks 24 7 welding just to get the legs joined to the spindle.
We had the world's third largest fixed crane capable of lifting 3000 tons we then bought
in the largest mobile crane also capable of lifting 3000 tons the reason we needed 6000 tons
of lifting capacity it's all about the reach so you've got to have the ability to lift 1800 tons
at a significant distance because you've got the legs in the way and things like that so that
lifting capacity drops quite significantly which is why we needed both cranes to achieve that lift.
While observation wheels look lightweight and simple once complete, getting them to
a point where they are self-supporting and won’t buckle under their own weight is an
extreme structural challenge - and the temporary support structure that makes
it happen is like building a whole second wheel within the rim itself.
Once you've got a wheel that's fully built and it's a circle like a bike wheel
it's very strong but the stage before that is you're trying to actually
create that circle that's the challenge so we started building it up in I refer
to it as almost the Dairy Lee cheese boxes you might be familiar with where you've got
the eight triangles that go to make up the circle and realistically that's exactly what
how we constructed this wheel and to do that we had what we refer to as a temporary rigid spoke
so that was made out of structural steel rather than cables now the rim itself because they were
very slender what we actually had to do is construct and convert the rim into a bridge.
Only when we created a bridge structure could it then span
between the two temporary spokes that we'd installed we were then able um to jack the
first segment 100 meters into the air that then allowed us to then lift in the second segment
we then put in another rigid spoke and we would then jack that around
now that sounds like a very quick exercise reality that process took three to four weeks
to actually go from installing to jacking it around to being ready to install the next piece.
Once the outer rim was complete, the supporting structure was removed by working
backwards - progressively replacing the bulky structural steel elements
with 192 pre-tensioned, heavy-duty cables that contain enough wire to reach from Dubai to Cairo.
That's 2,400 kilometres if you laid it all out flat, although no one ever does that.
Now we had to be really careful at this point because we couldn't
over stress the permanent spokes, so we went round and did a complete revolution
of this and again each of those exercises each of that removing the steel putting
in the new spoke cables tensioning up the spoke cables is taking about three weeks
you're almost into six months of work just to remove that steel work.
With virtually all of the Ain Dubai's structural integrity coming from the temporary framework up
until this point, every element was painted white to match the colour of the finished wheel – that’s
not for aesthetic reasons but to prevent the darker and lighter elements from expanding
unevenly in the Dubai heat - a phenomenon that could cause the rim to warp and buckle.
With its superstructure complete - the 48 passenger cabins were attached to the
outside of the rim in a methodical pattern - all to keep the wheel as close to balanced
as possible and to prevent its driving mechanism from becoming over stressed.
Now, speaking of the driving mechanism,
remember the jacking system that was part of the temporary works?
Well, that's now a permanent and integral part of the structure having been modified with 64
tyres positioned against the rim. They slowly rotate and push the wheel around using friction
at a rate of one revolution every 38 minutes.
Designed to carry up to 40 passengers at a time,
each cabin is more than double the size and weight of those on the London Eye.
Each has been fitted with a driving mechanism that has the
fairly fundamental job of rotating it at the same speed as the wheel but in the opposite direction
so that the floor stays horizontal no matter where it is in the rotation.
If all the passengers decide they wanted to go out to one side um in a Ferris Wheel but as you
might imagine the gondola would all rotate and it would start tipping this experience doesn't
happen because it's all driven and still we have a perfectly horizontal floor for the passengers.
Originally set to open ahead of Expo 2020, like most things last year, that just didn't happen.
Ain Dubai is now set to open on October 21st,
although press and invited guests will have already been for a ride.
What was my proudest moment there were many just in terms of some of these engineering feats and to
have been integrally involved um from the outset on it however probably the proudest was actually I
got the opportunity to take some friends and family up on the wheel to be able to share
that experience with them and just yeah that made me incredibly proud.
While some other great observation wheels have failed to achieve the same popularity as the
London Eye, Ain Dubai’s incredible height and unobstructed views will
undoubtedly make it the newest landmark in what’s now a city of engineering triumphs.
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