Well first, a 1-bedroom is the most expensive way to live, at the rate we're going we'll have 3-bedroom apartments with 3 families per bedroom instead of 3 bedrooms per family :). Back to the Industrial Revolution tenements.
You can get your human dynamic just fine on sidewalks, cafes, parks, etc. It doesn't need to be in-building. And even ~70 stories by elevator is still only a few minutes, nothing like the hour-plus train rides middle-class people in cities currently need to endure.
> You can get your human dynamic just fine on sidewalks, cafes, parks, etc.
More density means fewer [EDIT: more] people within walking distance of each café, park and restaurant. That, in turn, affects how many of them there are and how eclectic they can be.
Density is people over space. If you give each person more space, you reduce density. This can't be avoided.
> nothing like the hour-plus train rides middle-class people in cities currently need to endure
They don't need to endure it. Stamford, CT and Rochester or Port Jefferson, NY are nice cities with middling densities.
But many people don't want that. They want restaurants and nightclubs and parks with rotating art installations that only emerge and make sense when you pack people together.
Sure, you can put one or two large units in the mix without screwing things up. But not a lot, not for everyone. Else you end up with urban deserts.
>Some people don't want that--they want the restaurants and nightclubs and parks with rotating art installations that only emerge and make sense when you pack people together.
You really think a neighborhood of 70-story buildings can sustain these things as long as people share bedrooms, but can't the instant that children and young adults have their own doors to close?
>More density means fewer people within walking distance of each café, park and restaurant.
Vertical distance costs almost nothing in terms of time, given modern elevators and scheduling. I'll skip the cafe because it's a 40 minute walk instead of 10. You'd really skip the cafe because it's 20 floors down instead of 5? That's, like, one minute on a really bad day.
>If you give each person more space, you reduce density.
Well sure, but the advantages of density really come from compactness in time/ease of transportation rather than space. It doesn't matter that the restaurant is far away from its customers on the vertical axis, because elevators are fast.
Manhattan contained 854,000 housing units in 2014 [1] and 1.6 million residents between 2010 [2] and 2013 [3]. The average Manhattan unit has 1.2 to 1.3 bedrooms [4]. (For Core Manhattan, that average falls to 1.0 to 1.2.) So 1 to 1.1 million bedrooms.
If you mandated one bedroom per person you'd have to expel 31 to 38% of the population or increase the number of bedrooms by 45 to 60%.
Manhattan's 33.6 square miles [5] are populated with 70,826 people per square mile. If we go the culling-people route, that drops to 44,000 to 49,000 people per square mile. That's the population density of West New York, in New Jersey [6]. Manhattan and West New York are radically different places.
If we go the building-units route, consider that Manhattan gained 13,189 units between 2011 and 2014, i.e. 4,400 a year [1; Table 2]. To build the 500,000 to 600,000 bedrooms we need you'd need to make 415,000 to 500,000 units, i.e. a century of construction. (If you built only three bedrooms, you'd cut that time down to 167,000 to 200,000 units, i.e. a mere 38 to 45 years.) To build them in 20 years, you'd need to increase construction by 4.7 to 5.7x (90% to 2.3x if only 3BR), and that's ignoring any additional infrastructure that new population may need as well as population growth.
Cities are a product of density. If you try to make a city with suburban-sized personal spaces, you end up with neither city nor suburbia. Building up is better than sideways, always, but we shouldn't delude ourselves regarding realistic sets of trade-offs.
43% of the New York metro area is married, presumably many more are cohabiting. So, if we relax that constraint to "don't have to share a bedroom except with a romantic partner" then we are potentially already there.
Of course, the proportion of married couples could be much lower in Manhattan, and it's not necessarily the same 43%, but you get the idea.
More to the point I'm very interested what tradeoffs you think are worth literally never having the chance to be alone in a room. Without a shadow of a doubt I'd kill myself, and I'd never dream of brining a child into that miserable existence.
> if we relax that constraint to "don't have to share a bedroom except with a romantic partner" then we are potentially already there
50% of the Manhattan population lives alone, the same as the fraction that has never married [1]. So yes, what you outlined is approximately what's going on. (Just 12% of New Yorkers in rent-regulated apartments had more than 1 person per room; 4.4% more than 1.5 [2].)
The status quo isn't crowded per se. It's just crowded relative to suburbia. The point of my illustration was that small tweaks to density, e.g. one instead of one and a half bedrooms per person, quickly spiral at the scales and within the constraints of a city.
You can get your human dynamic just fine on sidewalks, cafes, parks, etc. It doesn't need to be in-building. And even ~70 stories by elevator is still only a few minutes, nothing like the hour-plus train rides middle-class people in cities currently need to endure.