How Dense is Too Dense?

Whenever people who support restrictions on building want to justify the limits of density, they say the area is too dense, or possibly too dense for the present traffic capacity or quality of life. This is true regardless of density. It’s against this background that one should read Kaid Benfield’s article in Grist attacking Ed Glaeser’s proposals for upzoning in Manhattan. Manhattan, we are told, is already the densest county in America, so why build more?

Multiple lines of response come to mind; you should think of them as separately as possible. The first is that Benfield not only makes an argument about Manhattan’s density, but also posts lovely images of landmarked streets in the West Village, which Glaeser wants to permit replacing with 50-story residential towers. In light of that, let us remember what historic districts are, in practice: they are districts where wealthy people own property that they want to prop up the price of. They are designated arbitrarily, make arbitrary rules, and protect clearly non-historic buildings.

The densest neighborhood in Manhattan, the Upper East Side, has about 46,000 people per square kilometer, rising to about 70,000 in the upper-middle-class (as opposed to wealthy) section east of Third Avenue. The West Village only has 26,000, so there’s clearly room to build up.

There is no inherent reason to go by county or borough density rather than by neighborhood density. By the same token, one could say that the Northeast is the densest region in the US and therefore requires no more density. Southern boosters might like this, but not the people reading Grist, who care about environmental protection more. There is no induced demand with people: allowing taller buildings is not going to make more people be born, which means all it does is permit population to shift from exurbs to city centers.

What is more, there already is demand for more housing in Manhattan: last decade Manhattan’s population grew faster than that of the rest of the city as well as the rest of the metro area, amidst skyrocketing rents. In fact the reason I don’t trust the census is that it believes that New York added more housing units than people last decade, at a time of rising household size and stable vacancy.

There are ways to increase Manhattan density without plopping 50-story towers everywhere. For one, even the Upper East Side has few such towers – it is built to about the 20th floor. Unlike with office buildings, which favor more agglomeration, residential buildings remain mid-rise even if higher densities were possible, as they were in the 1920s; today, on the order of 1% of the city’s residential stock is located above the 20th floor. However, any density increase requires a rise in height – from 5 floors to 7 in Harlem and the Village, from 10 to 15 in Morningside Heights, and so on – without the loss of lot coverage coming from project-style towers.

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15 Responses to How Dense is Too Dense?

  1. Yeah, that whole “It’s the densest, so why does it need to be denser?” line of argument is just idiotic. The US in the early 1900s was one of the best places in the world to be a woman, so why allow universal sufferage? California already has the most liberal marijuana laws in the US, so why legalize it completely? NYC already has the best transit system in America, so why bother with the 2nd Ave. Subway?

  2. Benjamin Hemric says:

    Hi, Alon — nice blog!

    Why I don’t disagree with the idea that many successfully dense urban districts can probably be even denser still and still remain successful, I also think there is some validity to the argument (which I’ve rephrased as follows) that “It’s among the densest now, so why should we have laws, regulations and public policies that would encourage even higher densities?”

    I think an important point to remember is that many parts of New York City (since we are using New York City as an example) actually have pretty low densities and could actually BENEFIT from increased densities. So by having rules, regulations and public policies that discourage added densities in THESE areas and instead having rules, regualtiaons and public policies that encourage the piling on of density in areas that have already greatly benefittied from high densities (the highest in the North America) there are three negative effects:

    1) The benifits of high densities have, so it seems to me, a point of diminshing returns. Encouraging added density in already dense areas, therefore, would have relatively little positive effect in such areas.

    2) Encouraging added density in already dense areas discourages and deprives areas that could use higher densities from getting them — areas where higher densities would have a much greater positive effect.

    3) Higher densities in already dense neighborhoods contribute (at least eventually) to the self-destruction of diversity in already dense neighborhoods and thereby they have a negative effect.

    As I mention (more or less) in my critique of the Glaeser article in comments section of “the Atlantic” (it’s my second comment, much further down the list when the list is arranged chronologically), “Why [eventually] kill the goose that is laying the golden egg, when you can instead protect it and keep it laying golden eggs — AND breed more geese to lay even more golden eggs?”

    It seems to me too, in terms of market urbanism, that a true marketplace situation (where zoning and public policies don’t interfere) discourages super high densities in already dense neighborhoods and encourages added densities in relatively low density areas the could benefit from them. This is basically because at some point successfully dense neighborhoods become more difficult to build in (finding appropriate lots, etc.) and less successful lower density neighborhoods become a wonderful opportunity with lots of upside. (When a product becomes too expensive, smart entreprenuers (sp?) try to create a cheaper alternative — that’s the marketplace.)

    Benjamin Hemric
    Friday, May 20, 2010 9:20 p.m.

    P.S. — Alon, if you have the chance — and only if it’s not too much trouble — could you give more details regarding the population figures you mention: e.g., “. . . the densest neighborhood in Manhattan, the Upper East Side (between what north and south streets?) has about 46,000 people per square kilometer (is there a figure for per square mile?), rising to about 70,000 in the upper-middle-class (as opposed to wealthy) section east of Third Avenue (between what north-south streets?). The West Village (between what boundary streets?) has 26,000. . . ”

    Ideally (and I don’t expect you to do this, because it would probably be too much work), it would be interesting to a) to see what the densities are in terms of dwelling units (which is the more customary way to discuss and compare densities); b) to see what the densities are for the various smaller segments of each of the areas.

    For instance the “West” Village (depending upon how its defined) is made up of a number of very different neighbhoods, which I suspect have very different densities. The same would seem to hold true for the Upper East Side — especially considering the humungous apartments on Fifth Avenue and Park Avenue and the town houses around them that one would think have actually contain very few residents. So one would think that THESE areas would actually have very low densities.

    Plus, as I mention in my critique of the Glaeser article, focusing on residential densities isn’t as useful in my opinion, as it might seem, as some areas have lots of commercial / industrial / institutional space that adds to real densities (in beneficial ways), but isn’t counted as residential density.

    • Alon Levy says:

      Thanks for the good word.

      But, you’re thinking of density the wrong way. The issue is not that we want as many square miles of land to benefit from density. We should want the exact opposite: human habitation taxes the environment, and diminishing returns to density ensure that a million people living at Manhattan density cause much less impact than a million people living at Atlanta density.

      On top of it, we should want more people to benefit from density, which means letting them live in a high-density environment if they choose to.

      The numbers as of 2000 can be found e.g. here for the UES and here for the Village. I think that excluding Roosevelt Island, which is less dense, CB 8 has 46,000 people per km^2; I may be wrong, but not by much.

      You can find census tract-level density numbers on the Factfinder. The only tracts in Manhattan that are those without residential development, because they’re parkland or commercial; on the UES, the least dense tract is 114.01, at the southwest corner, and it has about 15,000 people per km^2.

      • Benjamin Hemric says:

        First, thanks for getting back so quickly with the information!

        You make some interesting comments, which I won’t able to address more fully, if need be, until Monday evening at the earliest.

        But briefly put, though (hopefully), three quick things:

        1) It’s very interesting that people seem to have very, very different goals and objectives here — and it’s good that these are expressed and out in the open. Otherwise people wind up talking past one another.

        The Jane Jacobs goal (which is where I feel I’m coming from) believes there should be HEALTHY (self-generating, market-based) cities (for a variety of reasons, including economic and social ones) — and more and more of them to meet a growing world population. (I think Glaeser also shares this part of the Jacobs viewpoint.)

        The saving of the environment (to extend what I see as the Jacobs’ viewpoint) is a by-product. And it isn’t from piling more and more people into a relatively small part of a city but from having many successful high density districts — and by having many dense cities, which by their very nature are greener than suburban sprawl.

        2) It seems to me that it’s important to remember that the outer boroughs (to use the NYC example) and nearby northern New Jersey are not pristine undeveloped land, but already pretty well built up albeit oftentimes at relatively low density areas — so making them denser also helps save the environment.

        3) People should definitely be able to choose, but it seems to me that in a real world market environment, and market ecnomics being what they are, the tendency is not to over develop a a particular area but to “improve” others at lower cost. (People factor cost and price and what they get for them, of course, into what they want.) Thus when Greenwich Village became too expensive, artists moved to SoHo, Tribeca, West Chelsea, Williamsburg, Hoboken, etc., etc.

        So the real fight for allowing marketplace added density should be in areas that are already developed but are developed at relatively low densities (and thus cheap and easy to add density to), not in areas that are already very dense (and expensive) and are probably too expensive and difficult to further develop much anyway. Here is where anti-development zoning rules and policies, anti-high-rise rules and policies, inappropriate landmark districts, etc. are the REAL “market urbanism” problem, so it seems to me.

        Benjamin Hemric
        Friday, May 20, 2011, 11:35 p.m.

      • Alon Levy says:

        I’m only going to reply to point 3 – 1 and 2 deserve another post. What I’m going to say is that you can’t really say so easily that the market wants X instead of Y to happen when there are stricter regulations on Y than on X.

        With that in mind, it’s not really true that adding density in the Village is unusually expensive. Glaeser is more or less right that unless you’re building very high (>50 floors), the costs of construction scale linearly with height. The reason developers insist on out-of-scale skyscrapers is that there’s a fixed cost of design, land, and getting a zoning variance from the city and the CB. The first two there’s nothing that can be done about, but the last one could be fixed with somewhat more permissive zoning.

  3. Benjamin Hemric says:

    P.P.S. — Here’s the URL for my critique of the Glaeser article in “The Atlantic.”

    My comments are in three parts. The first two parts are together in one comment toward the middle of the page (when arranged “oldest first”), and the third part (that is perhaps most relevant to this discussion) is further down the page, towards the end.

    http://tinyurl.com/3hya955

    Benjamin Hemric
    Friday, May 20, 2011, 9:50 p.m.

  4. Benjamin Hemric says:

    PPPS —

    Alon,

    For a fuller discussion of some issues that are pertinent, I think, to this discussion, I think you (the Mathmetician (sp?)) might enjoy reading, in particular, the very last chapter of “Death and Life of Great American Cities” (Chapter 22?). Especially since Jacobs bases what she says (and quotes extensively) a work by a somewhat famous mathemetician (sp?), Warren Weaver, after whom NYU’s Mathematics building is named.

    She also discusses her beliefs about “nature” — which are quite remarkable since it seems like a preface to her later book, “The Nature of Economies” — which was written about 30 years later!!!!

    Benjamin Hemric
    Friday, May 20, 2011, 11:57 p.m.

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  6. Charlie says:

    “In light of that, let us remember what historic districts are, in practice: they are districts where wealthy people own property that they want to prop up the price of.”

    But if Greenwich Village were rezoned to permit high-rises, wouldn’t the land on which their property is sitting greatly increase in value? The historic district rules and regulations presumably put downward pressure on prices, too, as they increase the time and cost for maintenance, renovation and expansion projects. Aside from the question of whether they’re justified or beneficial for the city as a whole, I’m just not sure I see how the historic designations are propping prices up, rather than keeping them far lower than they might otherwise be.

    • Alon Levy says:

      First, upzoning makes each individual apartment less valuable, since there’s more supply. In addition, if your neighbor’s tract is upzoned and yours isn’t, then yours becomes less valuable.

      Second, in light of the first point, upzoning means that poorer people can afford living in the area. Demand for housing is inelastic, which means the ability to charge high rents is much smaller, which could actually reduce land prices. The ability to change things also introduces an element of uncertainty into property values, which means that for a fixed rent the price to buy is lower (the flip side of it is that for a fixed price, existing landlords charge higher rents). On top of this, letting lower-class people move in removes an aura of luxury, further reducing prices.

      This is exactly the behavior you see in upper-class suburbs. Residents of such areas cry property values every time someone suggests building multifamily housing, sidewalks, mass transit, or anything else that makes the area livable for people making under $80,000 a year. School integration is of course a complete nonstarter in such suburbs; the segregation is part of the appeal. The difference with the Village is that Village homeowners use less brazen language to describe this rent-seeking process.

      • Charlie says:

        Thanks for your response, Alon. I’m really enjoying reading the blog.

        As for upzoning — eventually supply may increase and bring down the value of the average unit, but at the moment of rezoning land values will jump to reflect the higher density potential (more units/acre), and should remain high.

        For instance, in Greenwich Village, if a $5 million townhouse can now be replaced by 20 $500,000 studio apartments on the same lot, yes the average resident probably would be “poorer” but nonetheless the land value is going to double or more to reflect this possibility. That value will accrue to the existing owner. If the owner is personally irritated by the prospect of apartments going in next door, that doesn’t change the fact that in financial terms, he’ll stand to benefit greatly.

        As you point out though, this sort of opposition to upzoning is almost universal in the suburbs, even though it appears to be against financial self-interest. Perhaps the forgone profit is considered an acceptable tradeoff for the benefit of living in a class-segregated neighborhood, even if that’s too politically incorrect to state openly. If the neighborhood’s in decline, the lack of high-density zoning’s not going to save it anyways as I wrote about a couple days ago.

      • Alon Levy says:

        Thanks for the kind words, Charlie. I think your blog is first-rate and frankly underread and underrated.

        I have one nit to pick: the $5 million townhouse requires less upkeep and therefore has a higher profit margin. Otherwise I don’t really disagree with your comment, except the people who run CBs are long-term rent-controlled residents and small long-term owners who’d be the last to sell if zoning were liberalized; big developers who profit from and push for upzoning both groups view as the enemy. For example, see the strong opposition of CB 9 to the Columbia expansion.

  7. Benjamin Hemric says:

    Alon,

    Hi! I hope you won’t mind if I comment using a dialog format as it helps me write quickly.

    - – - – - – - – - –

    A) Alon Levy wrote [added language within brackets is mine -- BH]:

    [Right now,] I’m only going to reply to point 3 [i.e., market economics being what they are, the tendency of the marketplace is not to over develop a particular area but to “improve” other less developed areas at lower cost] — 1 and 2 deserve another post. What I’m going to say is that you can’t really say so easily that the market wants X [denser housing in the outer boroughs] instead of Y [denser housing in already dense areas of Manhattan] to happen[,] when there are stricter regulations on Y [denser housing in already dense areas of Manhattan] than on X [relatively low density areas of the outer boroughs].

    Benjamin Hemric says:

    First of all, I agree that you can’t always predict what the marketplace will do in a given situation, and for me (and for Adam, the originator of the “market urbanism” blog, so it seems to me) the objective of “market urbanism” should be to remove all “unecessary” market restrictions and allow what happens to happen — whatever the outcome is.

    However, it seems to me that when you look at the way cities have actually developed under market conditions (e.g., pre-zoning, etc.), the process I describe is pretty much what happens. There comes a point when developers start to see that established high density areas present less opportunity (too much is already developed to the maximum, there is too much competition for what’s left, the area begins to lose some of its appeal with the destruction of landmarks and hyper density, etc.) and new, alternative areas present more and better opportunities (e.g., cheaper land, a chance to improve an area’s appeal with added density rather than lessen it’s appeal with added density, etc.).

    Furthermore, I think it’s untrue that there are stricter regulations in “Y” (i.e., already dense areas of Manhattan) than there are in “X” (i.e., relatively low density areas of the outer boroughs). Among other things, for instance, outer borough areas are usually zoned for lower densities to begin with, they have parking minimums, etc. And the outer boroughs have landmark districts too — which mostly have lower densities than landmark districts of Manhattan.

    What I’m saying is, more or less, “level the playing field” and then see what happens. You seem to be saying the opposite (although maybe I’m misreading what you are saying). You seem to be saying, “keep the [stricter, low-density] restrictions in the relatively low-density outer boroughs, but [further loosen the already less strict high-density] restrictions in the already very high density areas of Manhattan.

    – - – - – - –

    B) Alon Levy wrote [added language within brackets is mine -- BH]:

    With that in mind [i.e., that the already dense neighborhoods of Manhattan supposedly have stricter regulations than the relatively low density neighborhoods of the outer boroughs], it’s not really true that adding density in the Village is unusually expensive.

    Benjamin Hemric writes:

    For one thing, I think it’s important to remember that nicer apartment houses (with nice, competive layouts, etc.) usually take up the site of more than just one rowhouse. (For example, look at the nice, modern [very large] apartment houses that were just built on Sixth Avenue in the 20s — a BRAND NEW area, by the way, for such high-density housing, and a wonderful, relatively low-cost, opportunity for developers.) So, in order to build a nice, large competitive apartment house in an already very dense area, there’s also the problem of assembling an appropriately large and appropriately shaped site (without having to pay a premium to holdouts, etc.).

    That’s not to say that opportunities don’t exist in the Village (e.g., the St. Vincent’s site), but that when costs are high in a popular, high density area, even BETTER opportunities can exist in currently less popular, low-density (or industrially zoned) areas elsewhere (e.g., Greenpoint/Williamsburgh, Long Island City/Astoria, the brownstone neighborhoods of Brooklyn, etc.).

    - – - – - – - – -

    C) Along Levy wrote [added language within brackets is mine]:

    Glaeser is more or less right that unless you’re building very high (>50 floors), the costs of construction scale linearly with height. The reason developers insist on out-of-scale skyscrapers is that there’s a fixed cost of [1?] design, land, and [2?] getting a zoning variance from the city and the [community board?]. The first two there’s nothing that can be done about, but the last one could be fixed with somewhat more permissive zoning.

    Benjamin Hemric writes:

    With regard to #1, I’m not sure if I understand what you’re trying to say here, but it seems to me that you are agreeing with my original statement.

    With regard to #2, why have more permissive zoning in areas that are already the most permissive anywhere in North America (the original topic of my comment in this thread) and not have more permissive zoning in the outer boroughs, where such zoning is more likely to be helpful and less likely to be hurtful?

    Benjamin Hemric
    Monday, May 23, 2011, 9:05 p.m.

    P.S. — I may not have time to reply to any further comments, if any, until tomorrow.

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