# Of Stone Bridges



## Demesnedenoir (Jul 10, 2016)

Okay, so I'm looking at a pivotal point later in book 2... let's say there is a stone bridge, crossing a river, are there any historical references to how a people might go about destroying a stone bridge in a hurry, what techniques, tools might be used? Pre-gunpowder, and magic in't so developed. I'm assuming it's sturdy as heck, something more like the linked than other stone bridges I can find. Any thoughts appreciated! Yes, I can do pretty much whatever I want, but figured if I could find some historical bits it would fun.

http://en.academic.ru/pictures/enwiki/79/Olandalbymedbridge.jpg


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## DragonOfTheAerie (Jul 10, 2016)

The only way I can think of is weakening the structure by removing stones using picks and levers. If you damaged it enough at an important structural point it would collapse. 
But totally go with an acid-secreting magical lichen that spreads like kudzu, which dissolves the bridge.


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## Demesnedenoir (Jul 11, 2016)

LOL. Magic lichen to the rescue! As much fun as that would be, the setting is low magic and there's a ticking clock. I was thinking sappers, but the natural landscape here would lend itself to bedrock for the river banks. Those old bridges were bad ass built. Not sure there's a quick answer, which is just fine... I don't need the bridge destroyed, but want folks to have a good logical conversation about options. I hate it when stories skip something I think might work, heh heh.



DragonOfTheAerie said:


> The only way I can think of is weakening the structure by removing stones using picks and levers. If you damaged it enough at an important structural point it would collapse.
> But totally go with an acid-secreting magical lichen that spreads like kudzu, which dissolves the bridge.


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## DragonOfTheAerie (Jul 11, 2016)

Demesnedenoir said:


> LOL. Magic lichen to the rescue! As much fun as that would be, the setting is low magic and there's a ticking clock. I was thinking sappers, but the natural landscape here would lend itself to bedrock for the river banks. Those old bridges were bad ass built. Not sure there's a quick answer, which is just fine... I don't need the bridge destroyed, but want folks to have a good logical conversation about options. I hate it when stories skip something I think might work, heh heh.



If the bridge is over a river you could break a dam upriver and flood it. That's the only way I can think of. And breaking a dam probably won't be any easier than destroying a bridge. 

Does the bridge have to be stone? A wooden bridge is way more destroy-able. If the stone part's important you could have a wooden bridge set on stone pillars, or something.

Maybe the bridge could be old and already crumbling, and whoever a doing the destroying just does a little extra damage that does it in completely? 

Just throwing out ideas here.


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## TheKillerBs (Jul 11, 2016)

The only way I can think of in a low-tech setting is to literally have an army disassembling it stone by stone.


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## CupofJoe (Jul 11, 2016)

Fire. Fire will weaken and fracture limestone and sandstone, the hotter the fire the better. But it won't be fast. It might take days.
If it is a harder stone like granite, then I don't think fire will work or at least not without a lot of heat and time.
You could try pulling it sideways. Most bridges are built for compression loads but not with lateral ones. If the bridge is small enough then a few horses on a strong rope might tear it down.
The trouble with prying the bridge apart is that you have to be ON the bridge as you pry it apart. I can't seeing that being anyone's favourite job. maybe you can be under it but the same problem occurs. When it fails, you are going to be intimately involved.


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## RedMetalHunter (Jul 11, 2016)

Attacking the mortar, if there is any, would be the most effective. It is usually much weaker than the rock it holds together. Also attacking the arches (KEYSTONE) would also be more effective than other parts, but likely more difficult.

Rapid heating and cooling (fire then water) can causing mortar and stone to crack and weaken, but would not be an easy task.

That being said, I cannot imagine it would be a quick affair without a large workforce. Would there be more effective tactics? Covering the whole thing with debris and/or fire? Would also make a good choke point for attacks/counterattacks?


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## Devor (Jul 11, 2016)

CupofJoe said:


> You could try pulling it sideways. Most bridges are built for compression loads but not with lateral ones. If the bridge is small enough then a few horses on a strong rope might tear it down.



This one makes the most sense to me.

My immediate thought was a combination of selective disassembly and a mud slide.  All that weight has to rest on the ground, and there are ways that the ground itself can give way.

The easiest method might actually be a combination of methods.  Remove a few key stones, muddy the banks, and pull sideways with the horses.  Spreading some combustible magic lichen, letting it burn for a day or two, and then opening the dam might all help speed things along.

Another possibility is to consider whether you need to destroy the whole bridge, or just a part of it.  If it's large then the weight is probably supported in sections, and pulling out just one section might be easier than tearing the whole thing down.


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## skip.knox (Jul 11, 2016)

In the picture you provide, I don't see any mortar, so I'd go with picks plus oxen or horses to pull laterally. Once the surface layer is broken up, the lateral pull should be effective.

I cannot come up with a historical account of the actual destruction of a stone bridge. Destruction gets mentioned from time to time, but never with any details.

I'd go with some spectacular magic, like a small tornado or some such. The quick destruction of a solid bridge would be something for the bards.


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## Fluffypoodel (Jul 11, 2016)

Freak earthquake?


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## DragonOfTheAerie (Jul 11, 2016)

Maybe the area is surrounded by rocky cliffs or precariously balanced rock formations, and they're able to start a rockslide and collapse the bridge.


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## Ban (Jul 11, 2016)

Catapults, because catapults solve everything.


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## Ankari (Jul 11, 2016)

What about sapping? Have a few men dig away the ground around one support, or dig underneath it.


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## La Volpe (Jul 12, 2016)

Banten said:


> Catapults, because catapults solve everything.



Truth. Though I would correct this to *trebuchets. In any event, rocks big enough to damage city walls should be able to damage a bridge.


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## Russ (Jul 12, 2016)

It's engineering, physics and leverage baby.

Remove a few key stones.  Apply block, tackle, levers and fulcrums...game over.


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## Demesnedenoir (Jul 12, 2016)

The situation doesn't allow for trebuchet/catapult, and limited man/animal power. But all ideas are good ideas to think on.


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## Ban (Jul 13, 2016)

Alright I have another idea, but it might be a slight bit impossible in reality...

What if you cut down a large number of trees (provided there is a forest nearby), tie those trees to the foundations of the bridge and push them in the river. The force exercised by the trees and the water might be enough to cripple the bridge's foundation and... voila! No bridge.


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