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Disclaimer: First off, this is not a duplicate of this question. That question deals with stopping the hurricane, or preventing it from ever forming in the first place. It was discovered that wasn't such a bright idea, so I'm asking this question. This question deals with simply preventing any damage to cities while the hurricane is present.

Scenario: From my research, there are hurricanes nearly every year, moving up (or West) from the Gulf of Mexico. Every time a hurricane hits or even comes close to buildings, it inflicts a lot of property damage from the winds and flooding. Not to mention the potential for loss of life if the hurricane is bad.

We've determined that we need the hurricanes. @Mark said: "A hurricane is nature's way of moving heat from the equator to the poles. If you stop hurricanes, that heat is going to build up, and is going to find an outlet somewhere. Do you really want to risk being in the path of that "somewhere", when we find out what it is?" (comment on the above linked question)

Question: So if we need the hurricane, and if it causes a ton of damage, what can we do to prevent or at least significantly lessen that damage? How can we protect ourselves and our cities?

Details: I'm assuming that if we had a feasible way to do this, we would have done so by now. So I'll allow for a small amount of near-future technology that we don't quite have yet. Try to keep as close to reality as possible though.

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  • $\begingroup$ There is a very trivial approach: Don't build in tornado alley. And while you're at it: avoid places that see regular flooding. Compared to nature's forces, cities are tiny. $\endgroup$ – Burki Mar 9 '17 at 16:28
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    $\begingroup$ There's a really simple approach to this. It's not at all difficult to build buildings that are pretty much proof against hurricanes, it just costs more. So developers built cheap houses, and expect flood insurance and federal disaster aid to pay for rebuilding the cheap houses when they blow down. $\endgroup$ – jamesqf Mar 9 '17 at 19:23
  • $\begingroup$ @jamesqf How does one build a hurricane-proof building? $\endgroup$ – Thomas Reinstate Monica Myron Mar 9 '17 at 21:50
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    $\begingroup$ @Thomas Myron: I'm neither an architect nor a structural engineer, so I can't give detailed answers. You might look at buildings that survive undamaged after hurricanes. Of course there are obvious things, like bolting your structure to a solid foundation, not using shingled roofs, having storm shutters for windows. And the most obvious: don't build your effing city in a below sea level depression on a storm-surge prone coastline. (Yes, New Orleans, I'm talking about you :-)) $\endgroup$ – jamesqf Mar 9 '17 at 22:06
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    $\begingroup$ @ThomasMyron start with sturdy foundations, and not relying on weight alone to keep the house on the ground. Use heavy materials: brick, concrete, steel. As a plus, they also help with insulation, saving large amounts of energy for heating and cooling. $\endgroup$ – Burki Mar 10 '17 at 8:02
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How much are you willing to change cities? Are we talking about retrofitting existing cities to better handle hurricanes, or building brand-new ones specifically engineered to be hurricane-resistant?

There are two key weapons a hurricane uses to cause damage. Let's address each in turn:

High Winds

This is the defining element of a hurricane, and the primary cause of damage. The winds are generally strong enough to break trees and send unsecured objects flying at high speeds. How can we make our cities more wind-resistant?

Existing Cities

1. Minimise debris-forming structures.
Road signs, house siding, tree limbs...all these and more can become deadly projectiles in hurricane-force winds. Our hurricane-proof city should minimise all such loose material, replace signs beside the road with signs painted onto the road. Keep light vehicles (cars and motorbikes) inside sealed garages.

2. Domes.
Dome-shaped structures are ideal for surviving strong winds - traditional flat-sided buildings present a broad flat sail to the wind, which can and will build up enormous pressure on one side of the structure, often leading to catastrophic collapse. Domed structures, with their sloping walls, have no sail area at all, so the wind simply blows over them. They also present a stronger face to any wind-borne debris. Existing structures could be housed within domes to prevent future damage.

3. Storm shutters.
Of course, you can't eliminate flying debris entirely, so you'd probably want to make sure every structure had steel shutters that could be closed in the event of a storm to prevent windows from being smashed.

4. Elevate critical transportation arteries.
We saw in hurricanes like Katrina and Sandy, cleanup and rescue after the storm was hampered by damage or flooding of critical transport routes. Keeping a few arteries, like highways or rail tracks, a few metres above the surrounding terrain would make them less likely to collect debris, and easier to clear.

New-build cities

1. Build underground.
A city built beneath ground level would be largely immune to high winds, which would simply skate over the surface without touching the majority of the structure. The surface footprint of such a subterranean structure could be in the form of a dome, as well, providing all the previously-mentioned benefits. Transportation networks could also be kept underground, and impervious to wind.

2. Wind baffles
This is a less practical option, but it could work on a large enough scale. Essentially you would have the city surrounded and filled with large concrete (or magitech) baffles which could rotate to face the oncoming wind, effectively lifting the wind above the city and reducing the wind speed on the streets. This would probably be very expensive, though.

Storm Surge

In some cases, the storm surge associated with a hurricane can be more devastating than the winds themselves. Storm surge is a sudden rise in sea level caused by the winds blowing additional water ahead of them, and if low-lying parts of a city can be penetrated, they can be deadly. Once water begins flooding low-lying areas, it will likely keep going - and it won't flow out again of its own accord. It would need to be pumped out.

Existing Cities

1. Levees.
The brute-force approach. Levees are earthen embankments build to keep high waters away from an urban area. They're frequently used on rivers and canals, but they're also used in places to keep the sea back (see dykes in the Netherlands, etc). They're cheap, but once a levee is breached things are quickly going to get very bad.

2. Build high and strong.
Flood waters can be deadly. They carry debris and disease, and can quickly overwhelm and drown unprepared citizens. Thus you'll want to be sure that everyone has some high ground they can easily reach. The easiest high ground, of course, would be the upper storey of their own homes, so all houses should have at least two storeys. They should also have a way to get out of the upper story, in case flood waters begin to rise even above that point - in Hurricane Katrina, many people were drowned in their own attics because they could not get out. This is another case where building elevated infrastructure would help.

3. Flood gates.
These are the more advanced relatives of the levees mentioned earlier. Flood gates are literally heavy gates that can be closed across choke points like harbour entrances to keep high waters from passing through into the populated area behind. They're expensive, and can't protect areas along a very broad front, but they are practical in some situations.

4. Waterproofing.
It sounds silly, but if you can't prevent flooding in your city (say, because it's built below sea level...), you can at least seek to minimise damage by ensuring that important utilities and documents are protected from water damage. It won't help in the moment, but it will make recovery easier.

5. Pumps.
One of the reasons that Hurricane Katrina was so devastating in New Orleans was that the water stayed in the city for so long, and this was because the city's pump stations mostly failed. These pumps drew water from drainage canals and dumped it back into Lake Pontchartrain. Unfortunately, the pumps were not themselves waterproof, so when their motors got wet they became useless. Waterproofed pumps would be essential for clearing flooding quickly from the city.

New-build Cities

1. Don't build your cities below sea level.
It's just never going to work out well.

2. Compartmentalise.
If you built underground, this is especially important. You'll do all you can, of course, to keep your structures sealed against the water. That would include several sets of heavy steel doors to close against the outside, etc. But in the event that a structure is breached and begins to flood, you need to be able to seal tunnels that connect your underground structures to prevent the flood from spreading. Heavy steel sliding doors should be able to do the job easily enough. Ideally, they'd also have airlocks built into them so that the population of a flooding structure can be evacuated to another structure without opening the main doors.

3. Don't build your cities below sea level.
I don't think I can stress this enough.

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  • $\begingroup$ Thanks. I wonder... is it a good idea for houses to have something similar to a floating dock at the top: some simple platform with sealed air containers on the bottom that will rise up as the water does, and eventually float free of the pillar it's on? That would solve the elevation problem - you could even have single story houses, as the docks can rise infinitely. They could have locks on the side so people could lock them together if they float free, thus forming a single giant raft. Would that be feasible? $\endgroup$ – Thomas Reinstate Monica Myron Mar 8 '17 at 21:59
  • $\begingroup$ So new cities should be underground and above sea level ... isn't that hard in coastal areas? $\endgroup$ – sdrawkcabdear Mar 9 '17 at 0:16
  • $\begingroup$ @sdrawkcabdear No, not particularly: New cities should be built on ground that's above sea level - so no flood plains, please, New Orleans... - and consist of structures that are mostly below ground. It doesn't matter if the bulk of the structure goes below sea level, as long as the entrance is well above sea level. $\endgroup$ – Werrf Mar 9 '17 at 13:03
  • $\begingroup$ @ThomasMyron Those rafts would be terribly vulnerable to wind, though; they could easily be picked up and tossed violently around, potentially colliding with one another and causing serious damage to occupants. You're also going to still suffer serious damage to the permanent structure if it floods. $\endgroup$ – Werrf Mar 9 '17 at 13:06
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    $\begingroup$ I don't know about building underground to help with the hurricanes. Sure you mitigate the wind damage, but hurricanes come with lots of rainfall and potential flooding. I can't find any record of a skyscraper being damaged by a hurricane, not Andrew in Miami, or Alicia or Ike in Houston. Even the glass breakage is all down at ground level. $\endgroup$ – kingledion Mar 9 '17 at 15:39
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My first thought for protecting against hurricanes (or any kind of flooding/wind storm) is something that you can erect between the storm and the city. Obviously in the case of large cities that's going to take a lot of material, and that material isn't going to be cheap. So we need to aim for something that is strong enough to withstand the wind (and any objects picked up by it), watertight to prevent flooding, durable enough to be used at least several times (brings the cost down), and is not outrageously expensive or difficult to manufacture.

My idea: Giant Plastic Cones. I know, it sounds pretty stupid. Maybe it is. I haven't tested it out, obviously. But here's how I see it working:

  • Strength. It's been demonstrated that plastic can be manufactured to have extraordinary strength. I'd imagine a few layers of super strong plastic would get the job done.
  • Watertight. Plastic is obviously watertight (water bottles come to mind), so we're fine here.
  • Durable. Unless my research has misled me, plastic is one of the most durable substances we have around. Maybe not against a fire, but against wind and water I'd imagine it could take several large hits. Flying objects might be a bit of an issue, so the cones should be constructed with individual panels, which can be replaced by themselves, rather than replacing the whole unit.
  • Cheap. I'm no authority on the cost of manufacturing plastic, but I can't recall ever hearing about it one way or the other, so I would assume that it isn't among our more highly valued possessions.

The plastic cones are stored in large warehouses. When a hurricane approaches, the panels are affixed to tracks dug into the pavement around cities (similar to streetcar tracks - no impact on traffic). The panels cover the entire city, going over it as well as around it. This will keep the high winds out, as well as any objects that are flung high enough to get over the walls (roofs may not be practical, in which case you would just have walls). Some sort of ventilation system will be needed to prevent overheating if you have a roof.

Is this a feasible option?

(Also, should I put this here, or in my OP?)

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    $\begingroup$ No, it is not feasible. Scaling laws are unfriendly towards city sized structures and downright hostile towards building such structures rapidly. You'd always be better off using smaller or permanent structures. $\endgroup$ – Ville Niemi Mar 8 '17 at 20:27

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