Engineering in Ancient
Rome
Stacie Raucci
Associate Professor of Classics
&
Tom Jewell
Carl B. Jansen Professor of Engineering
Union College
Roman Engineering
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The Arch
Surveying
Construction Techniques
Construction Materials
Roman Roads
The Inverted Siphon
Roman Aqueducts
Roman Baths
Roman Engineering
• Historians have not developed a complete
account of Roman engineering
• Written record scanty, and what there is
may not be reliable (Vitruvius, Frontinus)
• Contributed little that was fundamentally
new to civil or mechanical engineering
• Drew heavily on the accomplishments of
captive people
Roman Engineering
• Applied the existing repertoire on a grand
scale
• Emphasized three developments that had
not been used widely
– Semi-circular arch
– Extensive use of concrete
– Concept of public works
• Public water supply was the most significant
aspect of Roman civil engineering
The Arch
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Materials
Construction
• Why multiple levels?
Surveying
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Crude instruments
Extremely accurate results
Horizontal leveling
Vertical leveling
Street networks
Horizontal and Vertical
Levels
• Developed by
Greeks
• Used for vertical
and horizontal
alignment of walls
and foundations
Roman Libra
• Plumb line for leveling
• No plans survive
• Recreated from description
• Most likely the main
instrument for leveling
aqueducts
Roman Surveying Staff
• Used with Libra
• Measuring differences in
elevation
Construction Techniques
• Reducing weight
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Hallow bricks
Sunken panels
Pumice stone as aggregate
Reducing thickness near top of dome
Construction Materials
• Fired brick (1st century AD)
• Hydraulic cement
– Volcanic ash (pozzolana) from Naples
• Concrete
– Lime into cement
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Terracotta and ceramics
Lead
Copper (very limited extent)
Bronze
Roman Roads
• 50,000 miles in empire
• Uses
– Military movements
– Communications
– Commerce
• Milestones every 1000
paces
Roman Roads
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Straight
Crowned surface
Drainage
Maintenance of
grade
• Smooth driving
surface
The Inverted Siphon
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Misnomer
Water seeks own level
Pressure pipeline
Way of connecting
aqueducts across
valleys
• h = energy loss in
siphon
• H = static pressure
The Inverted Siphon
• Multiple pipes made
of lead or sealed
terracota
• Valves to release air
when filling, or drain
siphon
• Lyon siphons
weighed between
10,000 & 15,000 tons
• Misconceptions
Artists Sketch of Toledo Bridge
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Depth of crossing ~330 feet
More than twice as high as any other bridge
Only evidence is fragments shown
Most likely was inverted siphon with lowest
tier the venter
Roman Aqueducts
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Planning
Construction
Operation and Maintenance
Importance to Roman Empire
Planning & Construction
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Assessing the source of water
Determining elevation difference
Mark out route
Section 0.8-0.9 m wide by 1.7-2.4 m high
Sides and bottom lined with waterproof
cement
– Increased discharge by 40-80%
Underground Sections
• 80 to 90% underground
– ½ to 1 m
– Security
– Out of way
• Manholes for access
about every 75 m
– Maintenance
– Repair
– Calcium carbonate buildup
removal
Ancillary Structures
Distribution Basin
Segovia
• ~100 ft high
• Built 1st Century AD
• In service until ~ 1900
Aqueducts
of Rome
• 12 Total
• 187,000
gallons/minute
• Three times as
much per day
as modern NYC
• Ran
continuously
• Flow records
• Lost up to 1/3
Roman Baths
• Main purpose of the
aqueducts was to support
the baths.
• Romans had a passion
for baths that far
exceeded any question of
cleanliness and hygiene!
One bath complex in
Pompeii was almost
a mile around.
Central Building
Terme di Caracalla
Circular Pool: from scale at bottom, diameter is ~33 m
That makes the area ~ 855 m2
So the 180 m3 must not be correct
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Probably originally a natural
water course
6th Century BC – made into
open channel drain
33 BC, covered during reign of
Agustus
Built to drain the low lying land
that ran through the Forum
Around 100 AD direct
connections to homes started
Emptied into Tiber River
Cloaca Maxima
Toilets
• Wooden seats
• Water ran
underneath to
wash
excrement into
nearest water
course
• Washing
facilities
included