12 Sep 2013 21:58 UTCThu 12 Sep 2013 - 9:58 pm UTC
How did people long ago (before the Industrial age, but even 2,000 years ago) build bridges over rivers, especially fast moving ones? I am interested in the ones that have foundations sunk into/onto the river bed, so not for example army floating bridges.
Caissons and cofferdams are popular now, but in those days they didn't have pressurised pumps. And I am not sure that they'd have had concrete (I think the Romans invented, or popularised, concrete).
Apparently the Pisek stone bridge was built on land and then taken to the river - what does that mean? They floated pieces weighing 100 tonnes into place? And does that mean each piece is sitting on the bed, not dug into it?
In this picture, which is not from long ago, how did they get this cylinder inserted 15 feet below the river bed?
13 Sep 2013 03:09 UTCFri 13 Sep 2013 - 3:09 am UTC
I'll add another tidbit to myo's helpful links:
Roman Building: Materials and Techniques
page 587 summarizes two key techniques for laying bridge foundations...unfortunately, the online book doesn't include images, which really limits the utility.
14 Sep 2013 15:27 UTCSat 14 Sep 2013 - 3:27 pm UTC
It sounds a bit mad: stop the river or put some giant barrels in, spoon the water out, then build inside.
I am guessing that when ramming wooden poles down into the river bed, they did this inside those barrels/cofferdams. If you try driving a pole down through water, the resistance will presumably mean very little force by the time it gets to the bottom.
I'm happy for someone to mark this answered, by the way.
22 Sep 2013 13:22 UTCSun 22 Sep 2013 - 1:22 pm UTC
The oldest surviving bridges do not appear to raise significant issues of
deep or rushing waters, as the flows are seasonal or intermittent. There
are four Myceneaen bridges dating from the Greek Bronze Age (c. 1250 BCE),
presumably intended for chariot traffic but still passable on foot:
[Arkadiko Bridge -- Wikipedia]
and the oldest "functioning" bridge in Izmir, Turkey (ancient Smyrna),
dated to 850 BCE:
[Caravan Bridge over "River" Meles]
For its connection with the epic poet Homer, see here:
[River Meles -- Wikipedia]
Tactics of diverting the flow of a major river are described
in several ancient accounts, such as the case of the bridge built
over the Euphrates River c. 600 BCE:
[Herodotus' _History_ Book I: Queen Nitocris of Babylon (para. 185ff)]
"[S]he built, as near the middle of the town as possible, a stone bridge,
the blocks whereof were bound together with iron and lead. In the daytime
square wooden platforms were laid along from pier to pier, on which the
inhabitants crossed the stream; but at night they were withdrawn, to
prevent people passing from side to side in the dark to commit robberies.
When the river had filled the cutting, and the bridge was finished, the
Euphrates was turned back again into its ancient bed; and thus the basin,
transformed suddenly into a lake, was seen to answer the purpose for which
it was made, and the inhabitants, by help of the basin, obtained the
advantage of a bridge."
[Map of Babylon in Nebuchadnezzar's Reign]
When excavated the bridge proved to be 380 feet long, and the stone
pilings to have been cleverly shaped to reduce hydrodynamic resistance.
According to the same source, the sudden fall of Babylon to Cyrus the
Great in 539 BCE was accomplished by diverting the Euphrates into the
same artificial lake basin, dropping the river level overnight (see
these events told also in the book of Daniel, chapter 5, referenced
in Isaiah 44:27, Jermiah 50-51):
[Persia captures Babylon -- Wikipedia]
More evidence of ancient hydraulic engineering is found in
Shustar, Iran, designated a World Heritage site by UNESCO:
[Shushtar Historical Hydraulic System]
"Shushtar, Historical Hydraulic System, inscribed as a masterpiece
of creative genius, can be traced back to Darius the Great in the
5th century B.C. It involved the creation of two main diversion
canals on the river Kârun one of which, Gargar canal, is still in
use providing water to the city of Shushtar via a series of tunnels
that supply water to mills. It forms a spectacular cliff from which
water cascades into a downstream basin. It then enters the plain
situated south of the city where it has enabled the planting of
orchards and farming over an area of 40,000 ha. known as Mianâb
(Paradise). The property has an ensemble of remarkable sites
including the Salâsel Castel, the operation centre of the entire
hydraulic system, the tower where the water level is measured,
damns, bridges, basins and mills. It bears witness to the know-how
of the Elamites and Mesopotamians as well as more recent Nabatean
expertise and Roman building influence."
* * * * * * * * * * * * *
For early evidence of underwater construction where diversion was
not feasible, we turn to a bridge-related topic, the building of
"artificial islands" or more specifically "crannogs":
[Crannog -- Wikipedia]
"A crannog... is typically a partially or entirely artificial island,
usually built in lakes, rivers and estuarine waters of Scotland and
Ireland. Unlike the prehistoric pile dwellings around the Alps which
were built on the shores and were only inundated later on, crannogs
were built in the water, thus forming artificial islands."
[The Scottish Crannog Centre]
"The Scottish Crannog Centre features a unique reconstruction
of an early Iron Age loch-dwelling... This authentic recreation
is based on the excavation evidence from the 2,500 year old site
of 'Oakbank Crannog', one of the 18 crannogs preserved in Loch
[What is a crannog?]
"Crannogs are a type of ancient loch-dwelling found throughout
Scotland and Ireland, while one has been discovered in Wales in
Llangorse Lake. Most are circular structures that seem to have been
built as individual homes to accommodate extended families."
"The earliest loch-dwelling in Scotland is some 5,000 years old but
people built, modified, and re-used crannogs in Scotland up until
the 17th century AD. Throughout their long history crannogs served
as farmers' homesteads, status symbols, refuges in times of trouble,
hunting and fishing stations, and even holiday residences. Here in
Highland Perthshire, the prehistoric crannogs were originally
timber-built roundhouses supported on piles or stilts driven into
"In more barren environments and in later periods tons of rock were
piled onto the lochbed to make an island on which to build a stone
house. Today the crannogs appear as tree-covered islands or remain
hidden as submerged stony mounds."