Turkey has a new bridge and it’s big – we mean really big.
It’s the longest suspension bridge in the world, spanning 4.6 kilometres across the
Dardanelles strait.
If you put it in London it would dominate the skyline and rise higher than the Shard,
the tallest building in Western Europe.
This remarkable feat of engineering quite literally connects Europe to Asia and crosses
one of the most important and busiest trade routes in the world.
But constructing it wasn’t easy, the $2.8BN megaproject had to withstand earthquakes,
storms … and politics.
This is how the world’s longest suspension bridge was built.
On 18 March 2022 Turkey’s President Tayyip Erdoğan opened the 1915 Çanakkale Bridge
It had finished 18 months ahead of schedule but had been a long time coming.
Now, the Dardanelles strait has always been a pretty critical piece of Turkey’s geography.
It’s a narrow stretch of water that averages just four kilometres wide and is vital in
connecting the Mediterranean to the Black Sea, giving some of the most resource-rich
countries access to the outside world.
The strait, along with the Bospherous, also represents the effective border between Europe
and Asia, and before the Çanakkale was built there were only three bridges and two tunnels
linking the continents at this point – all located in Istanbul.
As you might imagine, that caused plenty of congestion and a crossing over the Dardanelles
to solve the problem was first pitched way back in 1989.
Famed bridge designer William Brown was even commissioned to design a structure following
the success of his Second Bosphorus Bridge in Istanbul in 1988.
But the plans stalled.
In 1995 the project was declared unfeasible and it was more than two decades before another
idea was put forward.
This time around the funds were secured and engineering technology had progressed by 20 years.
It was time to make history.
Given the size of some ships using the Straits, engineers opted for a suspension bridge design.
Suspension bridge technology is more expensive than cable stayed bridge
technology the longest cable stayed bridge in the world has a span of around a little
bit more than half of Çanakkale.
And you can't go much bigger than that for for this type of span, which you would have to
due to the shipping, then you end up with a suspension bridge.
These are huge.
I mean, the vessels sailing through the Strait of Çanakkale are among the biggest vessels in the world.
Two enormous 318-metre high towers were planned on either end of the strait, supporting the
two kilometre main span between them, the longest of its kind in the world.
A pair of 59,000-tonne caissons were submerged some 40 metres below the surface, one on the
European side and one on the Asian side of the water.
They would act as the towers’ waterproof foundations.
Additional steel platforms were then attached so that the towers could be mounted above
sea level.
So a number of high environmental and accidental loads set that we're considering.
The wind loads...
we are concerned for aerodynamic stability and we are of course concerned with earthquakes.
We are concerned with with the ship impact loads and also very special consideration
for such a great bridge is to be able to handle the traffic loads.
But of course wind is the first and primary concern for such a long suspension bridge is
aerodynamic stability.
The Turkish government wanted the bridge to be opened in time for the country’s centennial
in 2023 – and that put a strict deadline on every element of construction.
The prefabrication requirement was primarily coming out of a request for so fast construction
time.
We had a very tight constructed schedule for this, which being one of the challenges.
So actually it is today.
It's not even five years since we started on this project.
Once the towers were finished, the cables between them were then strung strand by strand
in a process that took more than 162,000 kilometers worth of wire.
That's enough to loop around the globe four times.
The main deck was then suspended from the cables, an incredible 72 meters clear of the
water.
The Strait is notorious for strong winds and large annual storms, so the deck was built
with a twin box girder structure with a nine metre gap in between that helps winds to pass
through the bridge more easily and improves its stability.
So you have what we call a twin box, and we split the box in two we have a gap in the middle,
and then they are connected with cross beams, that works much better and
gives much better aerodynamic stability.
Now complete, some 45,000 vehicles are expected to cross the bridge every day.
It has transformed a ferry journey that at its worst could take upwards of five hours
to a mere six minute drive.
And despite its $2.8BN cost, the crossing is projected to add $5.7BN to the economy.
It’s actually all part of a wider infrastructure blitz that President Erdoğan has spearheaded
across the nation - including a new airport in Istanbul, rail and road tunnels beneath
the Bosphorus, and most ambitiously of all a proposed $15BN canal in Istanbul that would
effectively turn the city into an island.
Canal Istanbul is a 45 kilometer waterway running parallel to the Bosphorus Strait,
connecting the Black Sea to the Mediterranean.
Many say the multi-billion dollar project is far too costly given Turkey's economic struggles.
It's fair to say Erdogan's had his share of criticism for these infrastructure plans.
Opposition leaders call the megaprojects nothing but distractions ahead of the country's 2023 election.
We are against it because it threatens Istanbul completely its water, its nature,
its security and earthquake safety.
It threatens life.
As if its record breaking engineering weren’t enough, there’s more to the 1915Çanakkale
Bridge than ridiculous amounts of steel and a big span.
Firstly, the whole project is wrapped up in national symbolism.
Painted in the colours of the Turkish flag, its 2,023 metre midspan is an allusion to
the Turkish Republic's 100th anniversary in 2023, and the name of the bridge refers to
a World War I battle fought on this very site.
But it’s the contrast with war that is perhaps its most impressive trait.
The bridge was assembled by an international team from all corners of the globe: cranes
were shipped from Australia, designs were drawn up in Denmark, and finance came from
South Korea – all to build a bridge in Turkey that connects Asia and Europe.
A hundred years ago many of these countries were at war with each other, fighting on the
very shores the bridge is now built on.
The 1915 battle of Gallipoli, for which the bridge commemorates, is one seared into the histories of both Turkey and Australia.
The world’s new longest suspension bridge is a testament not just to engineering, but
to what can be accomplished when nations combine their talents.
At a time of such uncertainty and conflict this structure reminds us not just of the
power of construction but of what we can achieve on this planet when we work together.
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