Author Topic: WoK: Bridge Crews & Bridges  (Read 27210 times)

Eerongal

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Re: WoK: Bridge Crews & Bridges
« Reply #30 on: September 10, 2010, 08:08:39 PM »
Another good visual exercise, if you live in a city (or just care to do some Street View touring) is to take a look at the width of the alleys between tall buildings you pass by. If it's wide enough to admit a single vehicle, that may only be 10-12 feet wide, but its more than you would want to try and cross unaided if you were 5 or 6 stories up.

A bridge of 50 feet couldn't cross this particular chasm dimension without being weighted. Even then it might be a stretch.

Why? Because the diagonal distance required would be at least 46 feet. A typical "story" in height is between 9-15, (pending on ceiling height and flooring, etc), so that's at least 45 feet vertical distance, and with a 10 foot horizontal distance, using our handy pythagorean theorem (a^2+b^2=c^2), 100+2025 = 2125, or 46.1 feet, for our hypotenuse (diagonal distance).

You're going to need to go way past half way for the arc of the bridge swing to hit even remotely NEAR the edge.

Edit: and just a note, these are the minimum calculations given the supplied amounts. If it's 6 stories up (calculation was with 5) it wouldn't be possible to cross a 10 foot gap, as even at smallest story size (9 feet) we have a length of 54 feet to cover
« Last Edit: September 10, 2010, 08:12:13 PM by Eerongal »
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rjl

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Re: WoK: Bridge Crews & Bridges
« Reply #31 on: September 10, 2010, 08:39:33 PM »
Eerongal, you missed Inkthinker's point, he was suggesting nominal vertical difference, but both where you're crossing from and where you're crossing to are effectively six stories up, so you don't want to try and jump the gap even if it is only 10-12 feet.

Eerongal

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Re: WoK: Bridge Crews & Bridges
« Reply #32 on: September 10, 2010, 08:54:33 PM »
Eerongal, you missed Inkthinker's point, he was suggesting nominal vertical difference, but both where you're crossing from and where you're crossing to are effectively six stories up, so you don't want to try and jump the gap even if it is only 10-12 feet.

I'm fully aware that was his point, however, he's making it sound like this is about the dimensions of the "average" chasm they'd be crossing. I just wanted to point out that if this is, then they aren't using 50-foot bridges. The vertical distance plays a huge role in what can actually be done with the bridges (weighted or not)
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Morderkaine

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Re: WoK: Bridge Crews & Bridges
« Reply #33 on: September 10, 2010, 08:57:42 PM »
The bridges couldn't be weighted otherwise they'd fall into the chasms when they were pulled across from the other side.

Eerongal

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Re: WoK: Bridge Crews & Bridges
« Reply #34 on: September 10, 2010, 09:19:12 PM »
The bridges couldn't be weighted otherwise they'd fall into the chasms when they were pulled across from the other side.

Not necessarily. as has been stated, the side you're coming from is higher than the side you're going to. When they pull the bridge over, they could rest the weighted end on the cliff face, and pull out the front, letting the weighted side (resting on the cliff face) slide down, until they can just pull it over.
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douglas

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Re: WoK: Bridge Crews & Bridges
« Reply #35 on: September 10, 2010, 10:02:54 PM »
I'm fully aware that was his point, however, he's making it sound like this is about the dimensions of the "average" chasm they'd be crossing. I just wanted to point out that if this is, then they aren't using 50-foot bridges. The vertical distance plays a huge role in what can actually be done with the bridges (weighted or not)
I think you're misunderstanding the situation he's describing.  You're reading it as a bridge connecting the top of the building and the street.  What he meant was a bridge connecting the top of one building to the top of another.  The number of stories was supplied only to support that you really wouldn't want to risk falling that far from trying and failing to just jump across.  The building tops, the places the bridge would actually connect, are within 1 or 2 stories vertical distance from each other at most.

Inkthinker

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Re: WoK: Bridge Crews & Bridges
« Reply #36 on: September 10, 2010, 10:11:25 PM »
I see what he means though... it's not just the horizontal distance, but the distance added by the drop to the lower plateau. I think Pythagoras solves this one for us... if a=across and b=down, then a²+b²=c², where c is the length of the bridge needed to settle on both sides

But unless the drop distance is more than a few feet I don't think it should dramatically affect the numbers.

EXAMPLE: Bridge Four comes to a chasm 20' wide, where the other side is 5' lower than the side they're on (a good sized drop). The length of bridge they would need is about 20.6' (20² + 5² = 425, square root of 425 is 20.6155blahblahblah). Even if the drop was 10', they would only need 22 feet of bridge to get across. Once they push it past the halfway point, it tips down and drops onto the other side.

But your point was entirely valid, you have to consider the vertical drop in addition to the horizontal distance. An ideal bridging point is one that's less than 25 feet across, and less than 10 feet below your higher position.

And since we know the bridges are an effective traversal method (or Sadeas wouldn't use them), we can assume that finding locations which match this criteria going there and back is not that difficult. It's also possible that there are additional methods for getting the bridge across which are not described by Kaladin for whatever reason (such as extending the bridge most of the way, then sending over a couple bridgemen to jump the remaining gap and haul up the other end with ropes) that would allow you to bridge gaps which are level with or even slightly above your position. I'd even suggest lifting the bridge until the front end is higher and allowing it to drop onto the other side, but this would probably shatter the structure upon impact (or maybe not, depending on how its built).
« Last Edit: September 10, 2010, 10:33:50 PM by Inkthinker »

Eerongal

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Re: WoK: Bridge Crews & Bridges
« Reply #37 on: September 10, 2010, 10:21:20 PM »
Nono, I see what he means... it's not just the horizontal distance, but the distance added by the drop to the lower plateau. There is probably solid math to determine the length of the gap (pythagoras? if a=across and b=down, then a²+b²=c², where c is the length of the bridge needed to settle on both sides

But unless the drop distance is more than a few feet I don't think it should dramatically affect the numbers.

EXAMPLE: Bridge Four comes to a chasm 20' wide, where the other side is 5' lower than the side they're on (a good sized drop). The length of bridge they would need is about 20.6' (25² + 5² = 425, square root of 425 is 20.6155blahblahblah)

But your point was entirely valid, you have to consider the vertical drop in addition to the horizontal distance.

Exactly. It's not just the horizontal distance we're concerned with here, but the diagonal distance created where the bridge will be going. The bridge needs to be able to be pushed out far enough that the arc of the bridge falling lands solidly and in a stable position to continue on.

And yes, we would need to use the Pythagorean theorem to figured this out (a and b are the horizontal and vertical, in no particular order, and C is the length out bridge needs to be able to reach to)

It's true that a 5 foot or so drop isnt a big deal, but it all depends on how all this is actually measured out. We don't really have dimensions for anything,  so its kinda hard to say, but both horizontal and vertical distance are going to play into how the bridges need to be worked. If it's a huge drop, even though it isnt more than say 15 feet on average, we're gonna need to go out pretty far before we can let the bridge drop.

edit: also, inkthinker, your math is wrong. 25^2 is 625, plus 25 (5*5) added to it is 650, which is a diagonal distance of about 25.5 feet after rounding. When dealing with right triangles, your hypotenuse (The diagonal distance) is always gonna be greater than each side. So if there's a drop involved, you're always gonna need more length than your horizontal distance.

Further edit: wait, i see what happened. In the equation you put 25, in the text you said 20. your math is correct with 20 feet, just not 25 feet :P
« Last Edit: September 10, 2010, 10:28:55 PM by Eerongal »
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Inkthinker

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Re: WoK: Bridge Crews & Bridges
« Reply #38 on: September 10, 2010, 10:29:10 PM »
Heh... I should know better than to re-edit a post after I post it, but yeah. I don't think vertical variance is a huge factor in crossings... a gap that was 20 feet wide and 10 down would be make a heck of a slope, but it would only require 22 feet of bridge to traverse. A drop of 15 feet seems extreme.

When I mentioned being 5-6 stories up, I mean up from the bottom of the chasm, not up to the next plateau... I was saying you wouldn't want to jump a ten-foot gap when, if you miss, you're looking at a 60-foot fall.

I can see how that was misunderstood, but I can't think of any time when they cross up or down to that extreme.

I've been more curious as to how the bridge men get out of the way and then reassemble near the rear as the part of the bridge they're manning goes over the gap. If you don't get out of the way fast enough, your own men could push you over the lip while they're running out the bridge. And if you hang onto the bridge as it goes over the chasm, you're adding weight that throws out the balance... you're lucky if they don't shoot you just to keep your weight from tipping it down prematurely (after all, the bridge is worth a LOT more than you are).

I think I can envision it, but it's a heck of a relay.
« Last Edit: September 10, 2010, 10:33:04 PM by Inkthinker »

rjl

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Re: WoK: Bridge Crews & Bridges
« Reply #39 on: September 10, 2010, 10:31:59 PM »
They drop the thing then push it out. As their carry points are at least partly, if not wholy under the bridge, they have to be moved from carry points for it to be on the ground.

Eerongal

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Re: WoK: Bridge Crews & Bridges
« Reply #40 on: September 10, 2010, 10:45:40 PM »
Heh... I should know better than to re-edit a post after I post it, but yeah. I don't think vertical variance is a huge factor in crossings... a gap that was 20 feet wide and 10 down would be make a heck of a slope, but it would only require 22 feet of bridge to traverse. A drop of 15 feet seems extreme.

Yeah, that would be a 45 degree angle, which, i think, is still walkable, but difficult. Beyond that, it's gonna start becoming a "happy fun slide into battle!" situation.
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Omelethead

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Re: WoK: Bridge Crews & Bridges
« Reply #41 on: September 10, 2010, 11:00:55 PM »
Isn't soulcasting considered to be incredibly holy by Vorinism? It seems like using it for war might violate their beliefs.

And the Soulcast barracks?

rjl

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Re: WoK: Bridge Crews & Bridges
« Reply #42 on: September 10, 2010, 11:11:03 PM »
Heh... I should know better than to re-edit a post after I post it, but yeah. I don't think vertical variance is a huge factor in crossings... a gap that was 20 feet wide and 10 down would be make a heck of a slope, but it would only require 22 feet of bridge to traverse. A drop of 15 feet seems extreme.

Yeah, that would be a 45 degree angle, which, i think, is still walkable, but difficult. Beyond that, it's gonna start becoming a "happy fun slide into battle!" situation.
Umm, actually a 45 degree angle would be if it were x feet down and x feet wide (for any given x).

20 feet wide and 10 feet down, is closer to (though not) 30 degrees.

zarepath

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Re: WoK: Bridge Crews & Bridges
« Reply #43 on: September 11, 2010, 12:22:27 AM »
Don't the Parshendi jump all the distances?  If that's the case, I bet there aren't any 20 foot chasms. 

rjl

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Re: WoK: Bridge Crews & Bridges
« Reply #44 on: September 11, 2010, 12:38:26 AM »
Don't the Parshendi jump all the distances?  If that's the case, I bet there aren't any 20 foot chasms. 
The Parshendi even jump to the tower which apparently at the narrowest point would be risky for someone in shardplate to jump. So question, how much does shardplate enhance jumping ability. Parhsendi clearly have super jumping ability...