It aimed to be boasting of largest passenger
terminal in the world, world's busiest
airport by cargo traffic, and also one of
the busiest airports by passenger traffic in
the world. It was about to be the most
expensive airport project costing about US
$20 billion. And it was to be completed in
a record period of 6-7 years. The airport
was itself just a small fraction of the
whole project . Why I say so, lets see..
Major challenges it faced:
1. Site Selection - The search for land
began. But as no land was available, a
large artificial island was created
offshore by merging small islands.
Mechanism - The mountainous islands
had to be levelled which resulted in
removing 200 million tons of rocks by
giant earth movers. The excavated
rubble was used to fill the sea gap
between small islands. Before filling
the sea gaps by rubble, soft mud
(approx. 40 ft) had to be removed from
the sea (to ensure a solid foundation).
Hence the largest fleet of under water
dredgers arrived at the site. This all
proved to be the biggest land moving
exercises ever i.e. 600 million tons of
material was removed which is
enough to fill ancient Roman Coliseum
200 times. This created an island with
area of 12.98 square kilometre, which
added 1% to the land area of Hong
Kong.
2. Foundation of the Airport - Being in
the man made island, the airport
terminal was to be nailed to the
foundation to save it from ocean tides
which could blow off the terminal
from its foundation. The terminal was
nailed to the bed rock by concrete
piers/piles. Each pile weighed 25 tons.
Mechanism - It consisted of repeating
lattice of steel trusses. 136 such
lattices were produced each of 140
tons. Robotic operator crane, operated
by remote control was used to
assemble these steel lattices.
3. Body of the Airport - Hong Kong was
subjected to average 8 typhoons each
summer and these typhoons are said to
have one of the most destructive forces
on earth, consisting of 200 miles/hr,
composed of wind and water. Airport
would have to withstand typhoons.
Mechanism - Hence, the glass within
the airport was designed to break
under high wind speeds which would
relieve pressure on the building
allowing it to remain standing.
4. Connectivity to the city - As the
airport was constructed outside the
city, so to connect airport with the
main city, following modes were
adopted:
i) Underwater Tunnels - Mammoth
pre-cast concrete steel structures,
weighing 35000 tons (equaling weight
of an ocean liner) were laid 50 ft
under water up to 1 mile for 6 lanes.
Mechanism - To prevent water from
entering them while being laid, they
were capped with watertight seals,
then put head to tail. The seals were
then removed carefully by hydraulic
jacks and the joint between each was
made air tight.
ii) Suspension Bridges - In another
area, where tunnel seemed infeasible
due to 3 mile width of water and
heavy traffic on the route. So bridges
were proposed. Longest bridges were to
be long enough to span the islands and
high enough to allow most gigantic
ships below it. To minimise the public
sufferings during construction, work
was done at night.
Mechanism - Detailed scaled model
results showed that the bridge would
become dangerously unstable during
high winds. But the bridges could not
be shortened, so were to be made
heavier, to stiffen them. 1000 tons pre-
fabricated deck stations were to be
installed in the span. The strength and
support to the bridge towers was
provided by 3 feet diameter cable
weighing up to 15000 tons. But all this
could not be assembled on ground and
then lifted in air. So they assembled
the bridge in midair by “double decker
mechanism” and “lifting each deck
section by the cables up to 200 ft to
install them at the required level”.
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