For centuries, bridges have helped us cross geological features - such as rivers, canyons
or rugged terrain - and in modern times we’ve seen them integrated into cities and our infrastructure
networks with an almost endless array of uses.
From humble beginnings, these structures have grown into some of the greatest engineering
achievements in human history.
Here we look at the longest bridges in the world.
To develop this list, we’ve looked as the longest bridges in each of the five main bridge
categories and used “continuous span” to define their length. As a result, elevated
highways or causeways with regular supports along their lengths are not included.
First up is the Ikitsuki Bridge, a truss structure built in the Nagasaki Prefecture of Japan,
that links the island of Ikitsuki to its larger neighbour Hirado.
Constructed in 1991, the 400m (1,312ft) steel span bridge supports itself through a system
of interconnected steel beams that form the triangular trusses of its superstructure.
These elements carry either compressive or tensile stresses with the counteracting actions
on each individual member allowing the bridge to distribute weight evenly when carrying
dynamic loads such as vehicle traffic.
Being one of earliest forms of modern bridges, truss designs are often incorporated into
other bridges due to the considerable loads they can carry for the material they use.
Next we have the Pont de Quebec, or Quebec Bridge in Canada. This steel structure takes
the title of longest cantilever bridge in the world with its impressible 549m (1,801ft) main span.
Completed in 1917, the bridge was dogged with misfortune throughout its construction,
collapsing not once, but twice before it was opened to the public.
The first collapse was the result of improper calculations relating to the bridges weight
and overall load bearing capacity.
In 1907, four years after construction began, the southern
and central spans collapsed into the St Lawrence River, killing 75 workers.
After going through a re-design, a second iteration of the bridge was commissioned and
began construction in 1913 with an even longer central span than its predecessor.
This time the bridge was overseen by three engineers, including an expert who had worked
on Scotland’s Forth Bridge.
However, these precautions didn’t stop the bridge from experiencing its second disaster.
In 1916, the hydraulic mechanism hoisting the central span into position failed and
bridge fell into the river below, taking a further 13 workers with it.
To this day, the collapsed section still lies at the bottom of the St Lawrence River.
When the bridge was finally completed in 1917 - after almost two decades of construction
- it took the prestigious title of “world’s longest bridge”.
Despite losing that title in the decades that followed, the Quebec Bridge remains to
this day, the longest cantilever bridge in the world.
Arch bridges are one of the oldest types of bridge and come in a wide variety of forms.
From the early stone arches used by the Greeks and Roman, to the steel giants of today.
The longest of these, with a central span of 552m (1,811ft) is the Chaotiamen Bridge
in China.
Built in 2009 the road and rail bridge stands
142m above the Yangtze river with a total length of 1,741m (5,712ft).
Despite varying greatly in appearance, arch bridges are all based on the same engineering
principle of distributing loads from the centre of the structure outward into abutments at
either end.
This can be done through foundations or pylons, like with the Sydney Harbour Bridge, or the
earth itself as is the case with the Mike O’Callaghan-Pat Tillman Memorial Bridge,
in the United States.
With a main span of 1,104m (3,622ft) the Russky Bridge in Vladivostok was built to connect
Russky Island to the Russian mainland ahead of the 2012 APEC summit.
With its total length exceeding 3,100m (10,200ft) The Russky Bridge needed some of the tallest
pylons of any bridge in the world in order to carry it's remarkably long road decks.
Reaching 321m (1,053ft) into the air, the bridges two massive pylons are taller than
New York’s Chrysler Building.
From these towers 168 cables, some as long as 580m reach out to support the 4-lane roadway below.
Controversially, the bridge was built at an estimated cost of USD $1.1BN with a capacity
to carry 50,000 cars every day. However, with the population of Russky Island at just over
5,000 people, the bridge is severely underutilised and considered by many Russians to be a white elephant.
All of the world’s longest bridges use the suspension principle and the longest of these
is a true titan of engineering. With a central span of almost two kilometres, the 1,991m
(6,532ft) Akashi Kaikyo Bridge in Kobe, Japan is the longest bridge in the world.
Built over the course of a decade - between 1988 and 1998 - the bridge was
developed to address a range of issues.
The Akashi Strait is a major shipping lane that is notorious for severe storms, so any
fixed crossing had to avoid large numbers of supports across the channel.
On top of this, the bridge lies in one of the world’s most seismically active zones; the “Pacific
Ring of Fire”.
To overcome these challenges, engineers developed a structure that was able
to span the vast distance whilst being able bend and flex without suffering serious structural
damage.
The roadway is hung from vertical suspension cables attached to the main cables strung
between the bridge’s two supporting towers. These cables are anchored in the bedrock at
each end of the structure.
Originally designed with a main span of 1,990m, the city of Kobe experienced a 7.2 magnitude
earthquake in January 1995 while the bridge was still under construction.
The resulting ground shift pushed the bridges two supporting towers apart resulting in an
additional meter (three feet) of roadway being added to the structure to complete the deck.
A dual-hinged stiffening girder system and tuned mass dampers in each of the two support
towers of the bridge mean it can withstand 286kmh (178 mph) winds and earthquakes measuring
as high as 8.5 on the Richter Scale.
Built at a cost of USD $3.6BN the Akashi Kaikyo Bridge remains one of the most expensive bridges
ever constructed.
Of course we couldn’t end this video without recognising some of the former record holders,
and most famous bridges from around the world.
Stretching 1,280m (or 4,200 feet), the Golden Gate Bridge in the United States was the world’s
longest between 1937 and 1964.
Sydney Harbour Bridge in Australia was the world’s widest between 1932 and 2012 - with
a width of 48.8m (169ft).
And the Millau Viaduct in France remains the world’s tallest bridge to this day, with
pylons standing 343m above the ground.
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