When and where was the first time moveable bridge?

Question

Transportation of goods on rivers have been important throughout history, all the way back to the earliest civilization in Mesopotamia, the Indus valley, Egypt, China and more (this might not be the best source in the world, but this should hardly be a controversial claim).

But these same civilizations were also building bridges across their rivers (If a source is necessary this will have to do).

For this reason, I always assumed that some kind of moveable bridges across rivers (to allow passage without impeding ship traffic) must have been very common, even in ancient civilizations such as -- to name only a few -- Egypt, Mesopotamia, Achaemenid Persia and at the very least Rome and Han or Tang-china -- and perhaps even medieval Europe; I acknowledge that such mechanisms would need maintenance and crew to operate them, and a great deal of technical skill to build, but in this regard the ancient civilizations such as Rome or Han China don't seem to have been lacking.
To my own great surprise, I have not been able to online find any examples of moveable bridges (meant to allow ships to pass under, thus excluding medieval drawbridges, whose use was purely defensive) older than the Old London bridge and this source does not specify directly that this was the first moveable bridge ever

My question is, therefore, when and where is the first time moveable bridges appear in history.

Edit: after a little more searching I did come across the 1174 Gaungji Bridge, which one source I found (whose reliability I strongly doubt, as it is a tourist website, for which reason I do not consider my question answered satisfyingly) claim to be the first movable bridge in the world.

Answer 1

The most likely early example of a movable bridge (assuming you allow pontoon bridges) allowing a ship to pass either under or through is Xerxes' pontoon bridge from 480 BC and is cited by Herodotus. Between this and the old London bridge completed in 1209, there is little that one can confidently say qualifies.

---

With Xerxes' Pontoon Bridges (480 BC) the bridge builders left (Hdt. 7.36.2)

a narrow opening to sail through in the line of fifty-oared ships and triremes, that so whoever wanted to could sail by small craft to the Pontus or out of it. After doing this, they stretched the cables from the land, twisting them taut with wooden windlasses; they did not as before keep the two kinds apart, but assigned for each bridge two cables of flax and four of papyrus.

Unfortunately, Herodotus doesn't provide much detail on this. There were, apparently, three openings but how they were 'constructed' is unclear.

This 2005 University of South Africa master's thesis, From the Scamander to Syracuse: Studies in Ancient Logistics (pdf), proposes that ships passed under the bridge thus:

All types of sailing ships of the time had masts which could be easily unstepped. A passing cargo ship would have needed headroom of two metres at the most with its mast unstepped in order to pass under the bridge cables. With that in mind, it is suggested that the simplest solution to the problem would have been for four triremes on each side of each “gap”, that is, 24 altogether, to have been modified by fitting baulks about twenty metres long lengthwise, raised by 25, 50, and 75 centimetres and one metre successively above the deck level, to lift the road over the cables by a gentle slope to about 2 metres above water level which would have been sufficient for a merchant ship to pass underneath.

On the other hand, Otis Ellis Hovey's Movable Bridges (1926) states that parts of the pontoon could be pulled aside to allow ships through:

at three places boats were lashed together and arranged so that they could be swung aside to allow ships to pass through the openings. These appear to have been genuine pontoon draw spans.

With the Romans favouring fixed arch bridges and with evidence from China inconclusive, Hovey then adds

...it is difficult to trace the use of movable structures for several centuries after the beginning of the Christian era.

This brings us to Old London Bridge (cited by the OP and also by Dijkgraaf in a comment). Started by Henry II in 1176 and completed in 1209 during the reign of his youngest son John, it survived 600 years; a

particular feature of Old London Bridge was the drawbridge which was sited near the middle of the bridge.

"Detail from a 1632 oil painting, View of London Bridge, by Claude de Jongh." Note the movable (drawbridge) centre section. Source: Londonist

This allowed tall ships to pass through and the bridge was also notable for the houses and shops on it, though it was not unique in this respect. Interestingly,

Old London Bridge reached its pinnacle of fame in the sixteenth and seventeenth centuries. Tourists came from all over Europe to admire what was considered a wonder of the world.

Perhaps the centre drawbridge was partly a reason the bridge being 'a wonder of the world'; there is certainly scant evidence for other bridges across rivers with a movable section for ships to pass through which dated from the high medieval period.

---

Very borderline cases

Hovey's Movable Bridges has a section on Ancient Movable Bridges. He covers ancient Egypt, but makes no mention of ships being able to pass under and there does not appear to be any evidence that such bridges existed. At most (citing Edward H. Knight),

the Egyptians built no permanent bridges across the Nile, but were familiar with framing trestle work, and with pontoon draw bridges.

For the 6th century BC Chaldean bridge mentioned here, there is no evidence that it was movable; it may have had a removable section to allow ships to pass, but we can't say for certain.

Hovey also cites Herodotus on Queen Nitocris of Babylon's bridge (circa. 460 BC) across the Euphrates which had "movable platforms". The purpose of these, according to Herodotus, was to prevent robbers crossing the bridge at night.

Finally, Wikipedia's Bascule Bridges article says these date back to ancient times but provides no sources, and nor is there any mention of ships passing through or under.

Answer 2

Question:
when and where is the first time moveable bridges appear in history.

Egypt 2nd Millennium BC, and we also know of one in Chaldea in the Middle East in the 6th Century BC. Then such navigable bridges disappeared until the middle ages. They began becoming popular, even common place after the Industrial Revolution with mass produced steel which was stronger and lighter than iron or stone and with the invention of engines capable of moving such structures.

Movable Bridges Types, Design and History
Moveable bridge is a bridge that can change position (and even shape in some cases) to allow for passage of boats below. This type of bridge has a lower cost of building because it has no high piers and long approaches but its use stops the road traffic when the bridge is open for river traffic.

The oldest know movable bridge was built in the 2nd millennium BC in the ancient Egypt. History also knows for one early movable bridge built in Chaldea in the Middle East in 6th century BC. Since then they were almost forgotten until Middle Ages when they again appeared in Europe. Leonardo da Vinci designed and built designed and built bascule bridges in 15th century. He also made designs and built models of swing and a retractable bridges.

Source:

• History of Bridges