TRAJAN’s BRIDGE ON DANUBE
SARASIJ MAJUMDER
In order to supply his legions fighting in Dacia, Roman
Emperor Trajan ordered the construction of a 1,135 meters (3,724 feet) bridge
across the Danube River. Apollo Dorus of Damascus, one of the best Roman
architects, and Mathematician designed a fantastic ARCH bridge with Stone
Masonry Piers and a Wooden Superstructure.
The bridge was fifteen meters (forty-nine feet) wide. It was
nineteen meters (sixty-two feet) above water.
The Trajan’s Bridge was high
enough to allow the ships to pass beneath.
The bridge enabled the Romans to move supplies and troops
quickly over the Danube River and thus greatly contributed to the Roman
conquest of Dacia in 106.
The Romans needed just three years to build a one-kilometre-long
bridge
It was all a demonstration of intelligence, persistence,
applied engineering and steady, focused work over long periods of time.
It was the best and most extraordinary example of this type
of construction of that period, and was carried out by the Romans on the Danube
River on 2nd Century A.D.
Apollo Dorus admirably designed and built the bridge over
the course of 3 years and with this monumental construction the Roman legions
were able to establish a road across the river and keep their supply lines open
and secure in order to subdue the Dacians, mortal enemies of the Roman Empire.
limes from the north of the empire.
General features
The structure was 1,135 meters long, as the Danube is about
800 meters wide in area and 15 meters deep, reaching 19 meters above river
level. At each end there was a fortification (Castrum), which one had to pass
through to cross the bridge.
The bridge, designed by the engineer Apollo Dorus de
Damascus, was made up of twenty wooden arches resting on square masonry
pillars. Each arch measured 52 meters in span and the pillars were 20 meters on
each side and up to 45 meters high and were made of Stones, bricks ., mortar and pozzolana cement.
The Romans needed only three years, from 103 to 105 AD, to
complete the bridge. That was an astonishing feat since the bridge was 1,135
meters (3,724 feet) long.
Apollo Dorus didn’t diverted the river to dry out the river
bed but made it possible to construct pillars made of stone, bricks and mortar using ,what is known
today a COFFER DAM TECHNIQUE..
The Romans used oak wood for the arches. The wooden
superstructure was assembled on land and then installed on pillars.
Wooden arches, each spanning thirty-eight meters (125 feet),
rested on twenty massive masonry pillars.
Pillars were forty-four meters (145 feet) tall, seventeen
meters (fifty-eight feet) wide, and fifty meters (165 feet) apart.
Despite its exceptional dimensions, it was built in a very
short time, between 103 and 105 A.D.. This speed has led some to speculate that
perhaps the river was diverted during the period of construction of the bridge,
however the Roman historian Dio Cassius denied it.
I recommend reading the novel by Santiago Poiseuille, volume
II of the Trajan Trilogy.
The most interesting part is how they built the foundations
or pillars of the bridge on a mighty river like the Danube and the solution is
really great. Still it is used.
As you can see, two log barriers are built with huge trees
separated by about 4 meters and filled with stones and trampled earth creating
a central space of more than 50 X 30, this is dried by means of a tube pump
system. designed by Archimedes of Syracuse. Once the space is reasonably dry,
the dry work begins with appropriate materials and finally the pillar is lifted
that serves as a support for the arches built in wood and on top of it the
platform also in wood and which is the road itself to give passage to troops,
wagons, sieged weapons and troop supplies. On both sides were built protective Forts
that controlled the passage.
Works were done from barges and using huge cranes to move
and place stones and materials; More than 3,000 men worked during a constant
construction period of no less than 3 years. The bridge served without major
problems for more than 50 years and the RUINS of this incredible work of
architecture are still preserved today. The Romanian government a few years ago
ordered the demolition of some part of pillars that prevented navigation on the
river.
Genius is the name, not only of Apollo Dorus, but of the incredible
Roman people who carried out lasting works over time, such as this bridge made
of stone and wood.
The cofferdam system is still used today to build modern
bridges... and its principle has been conceived for millennia.
I explain it to you with a sketch below:
Unfortunately, Trajan's Bridge was demolished in the
3rd century, by order of the Roman emperor Aurelian, during the retreat due to
the attack of barbarian tribes. The bridge was built in a very short period of
time during that time, from 103 to 105. But there are still some fragmentary ruins of the bridge's piers that are
still visible today. It is located near the city of Drobeta-Turnu Severin in
Romania and Kladovo in Serbia.
References:--
1. Roman History—Gibbon., and other sources, my visit.
2.
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