eli5: How did people build bridges over deep and/or dangerous water if they didn’t have the equipment to go under water?
In: 22
They drained the water.
For building across a river you could wait until a dry season to build your bridge when the water level would be low or you could sink logs into the ground to make a sort of dam around your construction site which you could then drain(either using pumps or just buckets depending on technology) then you build your support pillar before breaking down the dam you built.
Mostly, it involved building in the safest and easiest place instead of the most convenient for travel.
TLDR: boats
Suspension bridges at a basic level only required a rope to be pulled across a river, and that can easily be done with a boat.
Larger footings could be poured from a boat as well.
While there’s a lot of prep work and drilling down on a river bed for bridges today, it more ancient times they would likely have just floated a barge to the spot and dumped large quantities of gravel and large rocks to create a solid footing
There are many different ways to do this depending on the available technology, cost and the ground conditions. For example we know the ancient Romans had pile drivers on barges which they could use to drive long piles into the river floor that would support the bridge. Some rivers would also dry up for some parts of the year, at least enough to build a bridge. Or the rivers could be partially drained for the construction. But even with these different techniques available the most common was still ferries at river crossings. Bridges are relatively new most places, most of them less then a century old.
They drained the water.
For building across a river you could wait until a dry season to build your bridge when the water level would be low or you could sink logs into the ground to make a sort of dam around your construction site which you could then drain(either using pumps or just buckets depending on technology) then you build your support pillar before breaking down the dam you built.
Mostly, it involved building in the safest and easiest place instead of the most convenient for travel.
They drained the water.
For building across a river you could wait until a dry season to build your bridge when the water level would be low or you could sink logs into the ground to make a sort of dam around your construction site which you could then drain(either using pumps or just buckets depending on technology) then you build your support pillar before breaking down the dam you built.
Mostly, it involved building in the safest and easiest place instead of the most convenient for travel.
They did not build bridges over “deep and/or dangerous water” before diving equipment existed. That is bridges with support in the water. Rope bridges and other simple suspension bridges have been built over rapids if the distances were short enough.
If it is even shorter you can build a solid bridge that is just supported by the ground on the sides of the river.
In relatively shallow and nice water you do not need to go underwater you can still expose the bottom.
The simplest way to explain this is by building an alternative path for the water and then making a dam with dirt and rock in the river. The old river bed is now dry and you can work on it. Destroy the dam and fill in the digestion and you have a bridge. It might not be the simple thing to do for a large river but it was possible.
You do not need to do that for all of the river, build a cofferdam that encloses parts of the river remove the water from the side and you can work there. The wall of the dame can be large baskets you fill with rocks and dirt to keep the water, coffer is an old word for the base.
Or build a small coffer dam by driving wooden pillars into the river bottom to remove the water. It only needs to be just larger than the pillar you intend to build to support the bridge. This is still common we just use metal walls bridges and other stuff that need access to a river bed.
https://en.wikipedia.org/wiki/Cofferdam
Another way is driving a wooden pillar into the bottom with a pile driver and letting that support a wooden bridge that extends a bit out in the air so you can drive down more wooden pillars. Ceasar’s army built bridges like that over the Rhine River in 10 days. It looked something like
https://c8.alamy.com/comp/BA805M/architecture-bridges-roman-bridge-of-gaius-iulius-caesar-over-the-BA805M.jpg
https://en.wikipedia.org/wiki/Caesar%27s_Rhine_bridges
So they built bridges over rivers with support in the river since ancient times but it was not very deep or dangerous water where it was done. It was quite shallow
TLDR: boats
Suspension bridges at a basic level only required a rope to be pulled across a river, and that can easily be done with a boat.
Larger footings could be poured from a boat as well.
While there’s a lot of prep work and drilling down on a river bed for bridges today, it more ancient times they would likely have just floated a barge to the spot and dumped large quantities of gravel and large rocks to create a solid footing
TLDR: boats
Suspension bridges at a basic level only required a rope to be pulled across a river, and that can easily be done with a boat.
Larger footings could be poured from a boat as well.
While there’s a lot of prep work and drilling down on a river bed for bridges today, it more ancient times they would likely have just floated a barge to the spot and dumped large quantities of gravel and large rocks to create a solid footing
They did not build bridges over “deep and/or dangerous water” before diving equipment existed. That is bridges with support in the water. Rope bridges and other simple suspension bridges have been built over rapids if the distances were short enough.
If it is even shorter you can build a solid bridge that is just supported by the ground on the sides of the river.
In relatively shallow and nice water you do not need to go underwater you can still expose the bottom.
The simplest way to explain this is by building an alternative path for the water and then making a dam with dirt and rock in the river. The old river bed is now dry and you can work on it. Destroy the dam and fill in the digestion and you have a bridge. It might not be the simple thing to do for a large river but it was possible.
You do not need to do that for all of the river, build a cofferdam that encloses parts of the river remove the water from the side and you can work there. The wall of the dame can be large baskets you fill with rocks and dirt to keep the water, coffer is an old word for the base.
Or build a small coffer dam by driving wooden pillars into the river bottom to remove the water. It only needs to be just larger than the pillar you intend to build to support the bridge. This is still common we just use metal walls bridges and other stuff that need access to a river bed.
https://en.wikipedia.org/wiki/Cofferdam
Another way is driving a wooden pillar into the bottom with a pile driver and letting that support a wooden bridge that extends a bit out in the air so you can drive down more wooden pillars. Ceasar’s army built bridges like that over the Rhine River in 10 days. It looked something like
https://c8.alamy.com/comp/BA805M/architecture-bridges-roman-bridge-of-gaius-iulius-caesar-over-the-BA805M.jpg
https://en.wikipedia.org/wiki/Caesar%27s_Rhine_bridges
So they built bridges over rivers with support in the river since ancient times but it was not very deep or dangerous water where it was done. It was quite shallow
They did not build bridges over “deep and/or dangerous water” before diving equipment existed. That is bridges with support in the water. Rope bridges and other simple suspension bridges have been built over rapids if the distances were short enough.
If it is even shorter you can build a solid bridge that is just supported by the ground on the sides of the river.
In relatively shallow and nice water you do not need to go underwater you can still expose the bottom.
The simplest way to explain this is by building an alternative path for the water and then making a dam with dirt and rock in the river. The old river bed is now dry and you can work on it. Destroy the dam and fill in the digestion and you have a bridge. It might not be the simple thing to do for a large river but it was possible.
You do not need to do that for all of the river, build a cofferdam that encloses parts of the river remove the water from the side and you can work there. The wall of the dame can be large baskets you fill with rocks and dirt to keep the water, coffer is an old word for the base.
Or build a small coffer dam by driving wooden pillars into the river bottom to remove the water. It only needs to be just larger than the pillar you intend to build to support the bridge. This is still common we just use metal walls bridges and other stuff that need access to a river bed.
https://en.wikipedia.org/wiki/Cofferdam
Another way is driving a wooden pillar into the bottom with a pile driver and letting that support a wooden bridge that extends a bit out in the air so you can drive down more wooden pillars. Ceasar’s army built bridges like that over the Rhine River in 10 days. It looked something like
https://c8.alamy.com/comp/BA805M/architecture-bridges-roman-bridge-of-gaius-iulius-caesar-over-the-BA805M.jpg
https://en.wikipedia.org/wiki/Caesar%27s_Rhine_bridges
So they built bridges over rivers with support in the river since ancient times but it was not very deep or dangerous water where it was done. It was quite shallow
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