A new lightweight lift cable will let buildings soar ever upward
economist.com
economist.com
He said the principal limiting factor for the height of a super-tall structure is economics.
In fact buildings over sixty stories or so don't make much sense in any real-estate market -- not even Manhattan or Hong Kong -- if viewed from the perspective of real estate as a commodity. Where supertalls make economic sense is if they can be turned into a prestige address when the building becomes a landmark.
With respect to wire rope, there is already synthetic rope with dramatically better tensile strength, and it's displacing wire rope in many applications. Synthetics have a lot less hardness than steel though, and are subject to abrasion. I don't know if a carbon fiber rope would be harder than a steel rope or not, but I know from experience that CFRP panels are not nearly as hard as steel plate.
It would probably also be practical to simply modify the bearing surfaces as well.
Without some elasticity the internal forces will destroy the cable. Not sure how elastic CF is compared to steel.
They may be able to help with some clever rope making techniques.
there is already synthetic rope with dramatically better tensile strength, and it's displacing wire rope in many applications
The article did mention the use of a dual layer anti-abrasian coating for durability.
Honestly though, why increase height and density still further? There are stupendous issues here with efficiency with regards to food, water, and HVAC - if nothing else. My personal view is that cities of the present are essentially anachronisms spawned from 20th century post-industrialism intertia: artifacts of outmoded labour markets, planning laws and now-quaint geospatial efficiencies.
As the cost of living in cities rises due to the shortage of land, the requirement for importing food and water, and the artificiality of maintaining a reasonable healthy lifestyle in high density urban environment, my bet is that, broadly speaking, emerging labour markets (our type of industry, for example) based on new technologies for communications and a reformed education system will cause a mass migration of professionals away from cities, back to a more sustainable, decentralized model. Sort of like the green banker-belt outside of London, but on a far larger scale.
In short, I believe that while the city will not disappear, its face will change .. and certainly not primarily through ever-taller buildings.
Good for health? No. Good for the environment? No. Good for corporate profits, ease of taxation, and established measures of economic trajectory including GDP? Yes. This is the story of the city, and its inhabitant is you.
Manhattan has some of the lowest obesity rates in the country due to inhabitants reliance on walking/public transit over driving. There are few studies that show a 2 year life expectancy vs rural areas in the UK, but it's not a totally clear cut win for rural areas overall.
"Good for the environment? No."
Yes, actually - it's a lot more efficient to deliver services to people in densely populated areas than when they're spread thinly across the country side.
"Per capita emissions in New York, Toronto and Barcelona are only a third of their national average, and the emissions of Tokyo, London and Seoul come in at about half of their countries' level." - http://www.newscientist.com/article/dn16819-city-dwellers-ha... - http://green.blogs.nytimes.com/2009/04/01/the-comparatively-... has a ton of other sources, including a brookings institute study and some others
No disagreement on corporate profits. Cities are also great as birthplaces of movements, musical genres, schools of art, and political theories. Think the east village during punk, detroit in the 50s for rock, the salons of paris around the French Revolution, etc etc.
There are definitely great reasons to live in rural areas, but being a city dweller is far from inherently worse.
Environment: What services are you talking about? Remember that to squeeze people together in the first place you have to import and maintain costly networks for moving food, water and energy. So dealing with decentralization from an efficiency standpoint should take this tradeoff in to account. As for the emissions references, I suppose they don't take in to account the ridiculous amount of pollution that goes on overseas or in other areas for products shipped in to cities (or the overheads of shipping itself).
I agree that historically there's great social and intellectual wealth in cities, but I personally believe that's now being eclipsed by non-geographic movements, many of which are largely fostered through the internet.
Cities benefit because you can bring in resources using more efficient means in larger quantities.
Energy and food are still a big deal, but the mix today is that shipping fuel has less impact on food prices than real estate value (that is, the food at rural stores isn't particularly expensive and they usually aren't that far away). They may be less economical than city stores, but they seem tenable.
I sort of think the trick is to figure out a set of policies that lead to healthy medium-high density areas, as it is most 'great cities' seem to be at least partly accidental.
Yet that is not how more than a miniscule fraction of houses in less densely built areas gets their water.
> Energy and food are still a big deal, but the mix today is that shipping fuel has less impact on food prices than real estate value (that is, the food at rural stores isn't particularly expensive and they usually aren't that far away). They may be less economical than city stores, but they seem tenable.
The real estate cost is irrelevant to the discussion of the efficiency of urban vs. rural energy and food delivery.
This is why I then start talking about making more good cities, because that should presumably remove some of the costs that are more or less associated with lack of supply.
In theory, cities are better. It's cheaper to build a road network for 10 million people than 1000 road networks for 10,000 people. You can ship stuff in with container ships, rather than trucks.
But this might cause people to be more wasteful. Everything is cheap and accessible, so they consume more stuff.
From wiki: 15% increase in service per capita with a doubling of city size (so it's not a fast quadratic).
There's TED talks, google talks, articles, and NYTimes articles on the wiki.
Can you back up your impression that there are stupendous efficiency issues with numbers?
In the USA multiple studies have been done on the question. They find that the per capita carbon footprint of people living in major metropolitan areas is lower than those living in smaller cities and the country. And NYC, that concrete jungle that epitomizes a disconnect from anything natural, is actually per capita the one of the 10 most ecologically friendly cities in the nation!
It may be unbelievable to you that it is environmentally friendly to pack people densely enough that walking and public transit become favored options. So I point you to http://www.brookings.edu/~/media/research/files/reports/2008... for a citation.
I would have thought that the cost of hauling food and water up 60 floors was self-evident? While I could go invest time finding numbers, to be honest I find it a bit rich that you ask me to provide sources while making equally unreferenced, sweeping and IMHO dicier claims in response.
For example, claiming the carbon footprint of city dwellers is low might be possible if it doesn't consider the cost of hauling the products they routinely use and throw away at rates far higher than other people on the planet... but that doesn't make it a realistic or truthful stance on the matter.
I am not surprised that NYC is low on obvious evils when considering this form of skin-deep environmental statistic, because it produces very little of... well, anything. As the center of finance, NY derives a great amount of wealth from achieving effectively zero of utility to the rest of the world.
For something more concrete, let's try measuring garbage. (I'm not going to get in to the interesting question of Wall St.'s facilitatory role in greater evils.) https://en.wikipedia.org/wiki/Environmental_issues_in_New_Yo... In September 2012, Travel+Leisure named New York City the #1 "America's Dirtiest City," from the results of a readership survey rating 35 "Favorite Cities" in the United States. It continues: In 2006 Mayor Michael Bloomberg signed legislation establishing a new solid waste management plan, which will use barges and trains to export 90% of the city’s 12,000 daily tons of residential trash. I can tell you that country people don't generate that much trash, and they can often dispose of it in a decentralized fashion (eg. via compost). Even Mexico City only produces 10,000 tons per day (random stat online), and its population is far higher and they probably actually make some tangible goods. But I'm not going to go build a well-referenced numerology of truth here. I hope you might be motivated to research further yourself.
The bottom line is that nature loves decentralization, and 'taxes' centralization. Cities are unnatural conglomerations that abhor nature. While we can sustain them, it's not the smartest thing to do in a finite world. Society is just beginning to learn from and invest in this with concessions to green architecture, urban design, public transportation, public communications infrastructure projects (Australia, China, France, New Zealand...), decentralized energy generation, etc.
What do I mean by cherry picking? Let's take your Wikipedia link, one sentence before the travel and leisure survey. New York City accounts for only 1% of United States greenhouse gas emissions while housing 2.7% of its population.
This is all consistent with what I said. NYC has a ton of people. Having a ton of people, it is inevitably an environmental eyesore. However, per person, it is environmentally better than the alternative.
Let's look at your garbage claim. NYC produces 12,000 tons per day of garbage. NYC has about 8.3 million people. That's 2.89 pounds of garbage per person. From http://www.cleanair.org/Waste/wasteFacts.html we see that the average American produces 4.5 pounds of garbage per day, of which 66.8% is sent to landfill. That's 3.01 pounds. Again, per capita, NYC beats the rest of the USA. Of course this is slightly unfair. Again, as you note, NYC has mostly outsourced its manufacturing. Manufacturing generates lots of garbage. I don't see an easy way to quantify that. However I do note that NYC has a high density of very rich people whose consumption can be expected to be above average.
I've lived in the country. Based on my experience, people who live in the country create tons of garbage, it is just not centralized.
It is true that Mexico city does better. However Mexico city is also poorer. Poor people, out of necessity, cannot consume much.
Next let's move on to your points about raising water. First of all, as https://en.wikipedia.org/wiki/Skyscraper#Environmental_impac... makes clear, it is true that it takes energy to put stuff high in the sky. But there are tradeoffs and it is not at all clear whether a skyscraper is or is not environmentally efficient.
But that's irrelevant. The population density of NYC doesn't require high skyscrapers. I've lived there. It is really dependent upon having small apartments, packed closely together. Most of the city is made up of buildings that are 5 stories high. (Because at 6 stories you need to install elevators.)
As for your general hate of cities, I submit that the facts don't support it. It is true that cities are unnatural, expensive things. However, per capita, they tend be more efficient. But fundamentally there is no way to support an unlimited number of people in a finite world.
You never heard of the economy of scale that comes with urban density? How would lower density makes the environment more "sustainable"?
For some basic examples: with more privacy, less pollution and lower rise building, people have a viable option to open a window when they're hot instead of turning on the air conditioner. Eating food from your own garden. Being more conscious of which food is in season, thus consuming more of it and less of the other stuff, saving on transport and artificial production overheads. Realistic capacity for grid-independent energy generation, wastewater disposal, rainwater capture, etc. There are plenty more.
(Edit: Seeing as people are apparently voting this down, I am honestly curious what they disagree with?)
If you are ever lucky enough to get the chance visit some more traditional cultures, you can see for yourself just how slight an impact they make on their environment, with houses, food, and clothes alike built from nature. It's amazing.
As the cost of living in cities rises due to the shortage of land and the requirement for importing food and water, those seeking life partners can increase not only their number of prospective mates, but the feasibility of finding one who makes a lot of money. Not to mention the availability and acceptability of almost any persuasion, hobby, or kink. Those souls most interested in health will have no problem finding a vegan delicacy at any mealtime, no worry of being stuck with some "salad" at McDonald's as the only option being any points A and B, and they can always hop a train to commune with nature.
Broadly speaking, the desire of people to live near thousands of their peers after graduation will cause young professionals to keep moving to cities, eschewing a life more connected with nature for one with a greater diversity of local work opportunities, events, and beautiful bodies. Just like London.
Anyway, to my point. I see no reason why new technology and interconnectedness is going to lead to the decline of the western city. My Experience suggests its more likely to lead to a greater desire among young adults to move to the urban cores (as they always habe), for Sex/Marriage, Culture and Nightlife as they see there own friends partake, so to speak. At the end of the day, extremely few people would find the internet an acceptable replacement to living amongst ones peers
I don't really know anything about architecture so maybe my intuition is off. Maybe these concerns are never realized with the number of floors that are practical for other reasons?
Edit: This link might be of interest... http://www.bloomberg.com/news/2013-01-02/double-deck-elevato...
This is like a lot of things in Dubai: roads, public transport and the airport which is currently being more than doubled.
Obviously this would require a completely different mechanism as you can no longer have cables attaching each car to the roof. In fact I have no clue how it could work! This is what I keep pondering...
Power fails, linear starts to fall, lands on top of the traditional otis with its emergency brakes holding the whole works up. There's no reason the cable between the otis and the linear has to be 200 feet for the linear to build up speed... make it, perhaps, 3 inches and a nice spring arrangement.
I bet it would still be pretty scary to be in one of those during a power failure. So put hybrid batteries on the linear motor so it can just keep on running during a power fail, perhaps programmed to do nothing but a normal controlled descent to the bottom doors. if ($powerfail == 'Y') { ignore_all_floor_selection_buttons_higher_than_this_floor; }
I remember hearing that elevators took up a quarter of the floor space of the old World Trade Center - only because they used express and local elevators, it would have otherwise been half the floor space. So it would seem a "vertical train" system could be quite valuable for saving real estate.
http://en.wikipedia.org/wiki/File:World_Trade_Center_Buildin...
Roughly 1/4 of the area is taken up with elevators, stairwells, and so on. So here's a back of the envelope calculation:
Elevator to office ratio: 1 : 3.
Proportion of floor area that is usable: 3 / (1 + 3) = 3/4.
To join the mile-high club, you need a building that's about 4 times higher. I will make the very crude assumption that, for a building that is 4 times higher, you will need 4 times as many elevators.
Elevator to office ratio: 4 : 3
Proportion of floor area that is usable: 3 / (4 + 3) = 3/7
Usable floor area compared to floor area of the old World Trade Center, occupying the same site:
4 * (3 / 7) ÷ (3 / 4) = 16 / 7; or about 2.3
So it's doable, but it's ridiculously inefficient. Where you draw the line is an interesting question. 100 stories is already pushing the limits, but you can alleviate this problem by tapering the building, like the Burj Khalifa. This is remarkably similar to how the pyramid builders solved their problems.
But what the pyramid builders really needed was the arch. And what modern engineers really need is an efficient vertical transport system. The obvious thing to do is have more elevators per shaft. Maybe something like a vertical cable car would work. Or even ditch the cables and make each elevator independently mobile within a network of interconnected shafts, like a vertical train system.
As you calculate, elevators are the new brick. The number needed to serve higher floors increase to the point the ground floor is nothing but elevators. So further height is pointless.
Its exacerbated by the need to fill/empty the building in bursts - people want to work regular hours, and everybody works the same hours. So you need enough elevators to essentially evacuate the building in under an hour.
Ways to work around this? Well, a pyramid structure would help I imagine. Elevators to server higher levels could be distributed evenly about the ground level, more in the center and fewer around the lower edges. That also increases windows-per-volume.
And of course if people lived and worked in the building and rarely left it, then the need to 'evacuate' from the ground floor goes away.
I imagine an arcology where people live, work and entertain in alternating levels. Fire and services can be located internally in strategic volumes. Air can be drafted up through the building using thermal gradients instead of fans.
Need to write a storey involving this kind of structure sometime I guess.
Use regenerative braking on the way down so you don't need a counter weight - although that does mean you need a much large motor, you might save on energy, but power requirements would still be high.
edit: completely overlooked counter-weight balance, see: https://news.ycombinator.com/item?id=5887522
Adding regenerative braking adds some form of energy storage - batteries, flywheel, compressed air, or whatever. A flywheel might be lighter than batteries, but torque I/O might affect passenger comfort.
It would be interesting to see how CF holds up over time. ISTR that Kevlar rope is very strong, but turned out to have unexpected issues with repeated jerky load/unload cycles. Presumably the CF elevator cable would have adequate testing before commercial use.
I'm also wondering this about CF - my understanding is it's strong, but has very poor abrasion resistance.
Even if you avoid external abrasion you can't avoid internal as the fibers rub against each other when they bend.
[1] http://en.wikipedia.org/wiki/Petronas_Towers#Lift_system (note, lift means the same thing here)
Pure carbon fiber is far too delicate to be used on its own without a matrix, but the fibers themselves behave very much like a lock of hair.
Something like electromagnets, rail gun style?
That said I have seen a few buildings with exterior "glass elevators" but it seems to be mostly a novelty.
https://dl.dropboxusercontent.com/u/3730003/fiber%20strength...
This is quite surprising as many synthetic polymers (zylon, spectra/dyneema, kevlar) are much stronger than carbon fiber. There is even a competition to make the strongest rope for potential space elevators:
http://www.isec.org/sec/index.php/technical-program/strong-t...
You have to have multi-stage lifts else the whole building becomes full of lifts rather than offices etc
Much more exciting for projects like loon I would have thought.
Lifts are also limited by speeds, if they go too fast they make some people queasy. This is also an issue to contend with since express elevator are limited in the 'express' bit.
Edit: to be a bit clearer if you split up a shaft into 4 sections with fours lifts you can have four lifts full of people being moved, hence your bandwidth is 4 times as much. Taken to extreme you have one for every floor http://en.wikipedia.org/wiki/Paternoster
It's really amazing to me that one of the things that holds skyscraper maximum height back is the practical concern of lift height. That's simply not the first thing I would think of if someone asked me the question.
But while that's cool, I don't think we necessarily should be building taller skyscrapers. They're not very practical. If they were, we'd have quasi-Coruscant cities where all the buildings were as tall as the Empire State Building or Willis Tower.
Instead, what tends to actually happen is the buildings become landmarks that attract a lot of attention but comparatively little real estate. Furthermore, when cities expand they generally need to build upwards quickly and forsake extravagance for practicality. If it takes 10 years to build a monolithic structure higher than the skyline, that's a project that's burning money for a long time until it's profitable.
If you put the motor in the car without ropes then it has to be powerful enough to lift the whole car and all occupants. And if you want any hope of energy efficiency you'd need regenerative braking for when going down. This would make the lift car a lot heavier and the electrical system a lot more complicated.
Sometimes simpler is better!
Also, a main problem with high rise buildings is loss of floor space at lower heights (the water, electricity, waste, and person traffic of floors 2 to N all have to pass though floor 1)
Ropeless elevators can have a huge advantage there, as they allow one to hang multiple elevators in a single shaft that both service the full range of floors. Yes, that requires sophisticated software to prevent lift cars from having to pass through each other too often (some designs allow cabines to do that by making it possible for the cars to move horizontally, too), but it is an active research area.
"ropeless elevator" is not on Wikipedia yet; the best (but tangential and possibly slightly commercial) I could find Googling it is http://www.barkermohandas.com/images/Integrated%20Vertical%2..., which is about a system with wires that allows one to move cars horizontally by sliding them from one car frame to another using linear motors.