Sunday, November 30, 2008

Framing Livable Communities: Density Terms

I guess we need to start a new series on Framing Livable Communities. Because of the intense press against density and transit, there are some things that need to be communicated differently. Today's instance is density and the need for the media to describe it as "packing people in". I might feel differently if we were setting up sardine tins like exists on the 30 and 38 buses, but density doesn't always mean Hong Kong just like suburbia doesn't always mean 1 unit per acre.

Not that this article from Raleigh Durham is a particularly bad one, but the headline "Raleigh Plan Picks Areas to Pack Growth" leads people to believe you're trying to force them to do something rather than giving alternatives to the single choice we currently have. We also know that focusing growth should be the true conservative point, due to the fact that actually saves money for cities and the people who live in them. Though it has been said that "density creates democrats". My hope is that when we make investments in our infrastructure including transit, that we make the decisions that save money for everyone and that includes smarter, denser growth. Growth that doesn't "pack us in".

13 comments:

Anonymous said...

"Walkable Communities".

What does "density" mean in urban development or transit terms?

It means there's a lot of people *who can walk* to each others houses, to stores, to libraries, to offices, to parks, to gyms, etc. (And to the transit stop.)

They're *close enough* to walk and they have *walking paths* (rather than having all the real estate devoted to parking lots and roads).

That phrase has the advantage of already being in use, as well as of emphasizing *why* density is inherently good. Density is good because you can walk to work, walk to the store, walk to your friends' houses/apartments, walk to the park, etc. Rather than having to drive there.

If you're truly, genuinely, antisocial, you can live in a low-density location without using a car -- a cabin in the woods. Hunt and scavenge for food, communicate by phone and Internet when you absolutely have to (perhaps for work). Such people create none of the problems we associate with sprawl.

Most people are social. For social people, being fairly close to other people is a good thing.

Most of us like our own space (which is why we have apartments and condos and townhouses rather than boarding houses and communes), but most of us don't actually need a vast amount of "mine all mine" space, because most of us like to spend most of our time with other people. At lunch time, restaurants, parks, and company cafeterias are full, although most workers *could* brown-bag it and eat quietly by themselves in their cubicle. What does this indicate?

Apartments should be required to have thick, sound-insulating walls and stuff like that, of course -- when you want to be alone you *really* want to be alone. But most people want to be alone *with other people within walking distance*, not miles away.

So, again, my vote is for "Walkable" as a good "density term" to use.

njh said...

Well said, Anon. I agree absolutely, even as a gardener I am happy in an apartment because I have a patio which I have covered in plants. And having good modern sound proof walls means that my place is indeed _my_ place.

Anonymous said...

Most people don't want to be jerkoffs like Cox or O'Toole, but want to "do things" with other people.

Morgan Wick said...

"Most of us like our own space (which is why we have apartments and condos and townhouses rather than boarding houses and communes), but most of us don't actually need a vast amount of "mine all mine" space, because most of us like to spend most of our time with other people."

What about families with children?

Alon Levy said...

Not all dense communities are walkable. Singapore has urban density of about 9,000 per square kilometer, but has a street plan based on winding arterial roads and cul-de-sacs. The difference between that and American suburbia is that Singapore's cul-de-sacs have high-rise projects connected by buses instead of single-stories connected by cars. However, with a few exceptions in the CBD and the older settled areas, there really isn't much for a pedestrian to do.

Anonymous said...

"The difference between that and American suburbia is that Singapore's cul-de-sacs have high-rise projects connected by buses instead of single-stories connected by cars."

In the 'vertical' version of a dense walkable community, the highrise contains commercial, residential, office, and parks all in the same building, so the 'walk' is up and down the elevator. Or, in the more common version, residential high-rises and commercial/office high-rises are adjacent and next to a park.

I'm guessing Singapore's arrangement isn't like that? It's cul-de-sacs of All Residential, linked to cul-de-sacs of All Offices, linked to cul-de-sacs of All Shops, by bus?

That indeed is a fairly unpleasant and rather stupid design. At least you can walk to see your friends if they're in the same high-rise apartment building, and you can ride rather than drive, but that's it.

One of the things the New Urbanism encourages is keeping home, work, and play spaces relatively near each other, which eliminates at least some of the endless commuting.

Alon Levy said...

I'm guessing Singapore's arrangement isn't like that? It's cul-de-sacs of All Residential, linked to cul-de-sacs of All Offices, linked to cul-de-sacs of All Shops, by bus?

Kind of. The offices are either in traditional downtown areas with few residences, or in office parks. The shops, too, are often located on traditional streets, in the older neighborhoods. But there are also commercial and even mixed use neighborhoods which are in cul-de-sacs with few, auto-oriented connections to the rest of the city.

njh said...

Families can live in apartments too you know. There are plenty around here. In fact, families in apartments in walkable communities turn out better than families in single family dwellings, on average.

Consider that many mcmansions these days are actually unwalkable apartments in every way except sharing walls (instead having two walls separated by a 1m gap, and if your aim is to isolate sound, it's much more efficient make that your design criteria, rather than making two walls - always be honest in your goal function).

As someone who grew up in places ranging from a small apartment in the UK through to a large house on the edge of a city, I can say that each place had good things and bad things, and that on the balance I don't see any advantage to exurban families over urban families. (Consider the many movie and TV families, living in urban or townhouses.)

Dave Reid said...

@Morgan Wick The idea that families need a 2500 sq foot home is a recent creation. There is no reason that families can't live in dense neighborhoods.

Alon Levy said...

It really isn't, Dave. In Ancient Rome, tenement apartments averaged 200 square meters. It's not that today's suburban houses are big, but that 19th century tenements were unusually small

njh said...

Alon, do you have a citation for that 200m² claim? Wikipedia is very confusing:

These houses were often constructed at minimal expenses for speculative purposes. The insulae were therefore of poor construction (timber, mud brick, and later primitive concrete) and prone to fire and collapse, as described by Juvenal. Because of the inherent safety issues and extra flights of stairs, the uppermost floors were the least desirable, and thus the cheapest to rent. Often those floors were without heating or running water and only sometimes had lavatories, necessitating the use of public latrines by their residents. Living quarters were typically smallest in the building's uppermost floors, with the largest and most expensive apartments being located on the bottom floors. The insulae could be up to six or seven stories high (some were even 8 or 9 stories high- these very tall buildings were being built before the height restrictions). A single insula could accommodate over 40 people in only 400 square meters (4305 sq ft), however the entire structure usually had about 6 to 7 apartments, each had about 200 square meters (2152 sq ft).

This is very confusingly worded, my best guess is that the building had a foot print of 400m², and housed 40 people, and was say 8 stories high. This would be 80m²/person.

I think 80m²/person is very achievable in conjunction with dense walkable environments. Let's run some numbers. Paris is one of the highest density western cities, at 25000 people per km². That works out to 40m² per person. But this is ground area, make the buildings 4 stories high (which has other benefits, c.v. Duany), take a coverage of 50% and you have 80m² per person (of course including road space). This is clearly quite adequate for lots of people(at least 12 million) and is really a very high density.

Now consider San Jose, where I live. Just 2000/km² or 500m²/person. Go up 3 stories (which is common practice), assume 0.5 coverage and you have 750m² per person, more than idyllic suburbia (1/4 acre block, 2parents2kids = 250m² per person). Stick allotments, swimming pools and community gardens on the roof and you bring it to 1000m² per person.

(corrections and flames welcome)

Alon Levy said...

Coverage in modern cities is very low. In fact, it's not even close to half - I suspect it's one eighth. It may have been one half in Ancient and Medieval cities; the reconstructed Medieval city I visited in France had very narrow streets, far narrower than those in any modern neighborhood, even Lower Manhattan or the City of London.

For an example, let's look at densities in Uptown Manhattan. First, a building's floor area ratio is typically about half the number of floors. A floor area ratio of 10, which exists on the most important streets and avenues, tends to translate to 20-25 floors. A floor area ratio of 6, common in most of the Upper West Side and Upper East Side, tends to translate to 10-15 floors. And a floor area ratio of 3.44, common in Upper Manhattan, tends to translate to 5-8 floors.

Now, let's look at the projected and actual apartment sizes. Upper Manhattan has a residential density of about 30,000 per urban km^2, after excluding parks. So that's 33 m^2 per person, times a residential floor area ratio of 3.44, which gives 115 m^2 per person in theory. In practice, the city's zoning board assumes an average of 63 m^2 per apartment, which at Manhattan's average household size is 31 m^2 per person. This is one quarter the theoretical value from the floor area ratio, and one eighth that from the height.

Similarly, the Upper East Side and Upper West Side have about 50,000 people per urban km^2, i.e. 20 m^2 per person. They're built at a floor area ratio ranging from 6 to 10. I'd say the average is about 8, from eyeballing the maps. That means 160 m^2 per person. The actual average is 73 per apartment, i.e. 36 per person, and the density is again one quarter what you'd expect from just floor area ratios, and one eighth what you'd expect from total height.

njh said...

alon, I don't understand, what is all that unused space for? Are 75% of all apartments unused?

Where do you get your numbers from?

Anyway, I am more interested in what we _could_ do than what is currently done. I don't see any good reasons to make apartments 'quaint' when we can make them spacious and comfortable with only small changes to plans.

Feel free to email me if you want to take this off-comments.