Density and Sustainability in Ann Arbor

Our failures with city neighborhoods, are, ultimately, failures in localized self-government. And our successes are successes with localized self-government. – Jane Jacobs, The Death and Life of Great American Cities

Density for Density’s Sake

As we have noted perhaps too many times (see Disruption in Ann Arbor: It’s a Promise), the heavy emphasis on dense development (“densification”) has been a consistent feature of Christopher Taylor’s tenure, both as a Council Member and as Mayor. This has accelerated in recent years, as summarized in this overview from MLive. While some developments follow the guidelines in the Comprehensive Plan, others have required special allowances and modified site plans.

Rendering of the 19-story building to be built behind the Michigan Theater, next to the old Liberty Square parking structure on the right

The culture of Ann Arbor has not always been so accepting of dense, tall development. As I described in an early article (2005) published in the Ann Arbor Observer, the fate of development downtown was intensely debated. But by 2010, the rezoning of downtown Ann Arbor was completely accomplished, via a process called Ann Arbor Discovering Downtown (A2D2). Since then, and especially when Christopher Taylor had a majority of his supporters on Council, downtown has been growing taller and taller. This was facilitated by generous height premiums for residential buildings. Perhaps the ultimate example is the building now underway behind the Michigan Theater. It will be 19 stories, according to the Ann Arbor News the tallest building in 50 years But as pointed out in the Ann Arbor Observer, with changes in the height premiums offered to require more affordable units, this era may be coming to an end. Still, the look and feel of our city has unalterably changed, as was well described in this article: Ann Arbor’s Small-town look fading as Downtown Reaches for the Sky.

Not all of downtown is available for this push to the sky. With Main Street and State Street historic districts, some of the precious land will stay at human scale for the time being. More recently, the effort has been to grow “downtowns” elsewhere by the simple expedient of rezoning parts of the city to accept less onerous height and density restrictions. The development site formerly known as Broadway Village was zoned as a PUD over a decade ago, but rezoned at the request of the current owner to C1(A/R), in a vote much criticized by Lowertown neighbors. As described in this review by the Ann Arbor News, till now this has been the most flexible or generous zoning classification. But the new TC-1 zoning, recently applied to the area around Briarwood, offers “downtown-style development” away from downtown.

This rush to development has been justified by the premise that more residential development (increase in housing units) of any kind will make housing more affordable in Ann Arbor. As Taylor was quoted in the discussion about TC-1 zoning,

“I’m very excited about this step we’re taking today…Supply and demand is not a joke, it’s the law, and what we are doing is we are enabling the market to create substantially more — thousands perhaps more — units of housing in the city of Ann Arbor to house future neighbors.”

While in the past, more permissive zoning like that granted in PUDs or the more recent affordable housing premiums for downtown have been tied to developer concessions and donations of “community benefits” like affordable housing funding and parks support, the tide has turned against any impediment to development. In the TC-1 discussion, some CM lamented the lack of requirements for a move toward carbon neutrality in accordance with the A2Zero plan approved by Council. But the no-benefits coalition won the day.

“Council has heard many people call for making developers propose fully electric buildings or include affordable housing in order to get approval for taller buildings, but requiring that could make projects more difficult and more expensive, (CM Lisa) Disch said, expressing concerns it could disincentive development.”


Cui bono?

So who benefits from all this development and the resulting growth? Obviously, the developers, who do this work to make a profit. Property owners make a sale, realtors and agents collect fees, many workers in construction trades, suppliers of building materials, construction managers, architects, survey companies find work. Taxing authorities acquire a higher tax base. And yes, politicians who support these policies are in turn supported by campaign donations. (We are not alleging corruption here. Individuals donate to candidates who support their goals, all open and aboveboard.) Growth of the GDP for a locality in general benefits many who do business in it.

But who benefits from the resulting density? That is a different question. There is a new urban science (beyond “emergent” and now well established) that seeks to define cities as entities that operate within the scientific/mathematical concept of complexity. One of the foremost practioners is Luis M.A. Bettencourt, author of the definitive textbook Introduction to Urban Science; Evidence and Theory of Cities as Complex Systems. For years, he and his colleagues have been conducting empirical work, collecting data of many types from cities globally, and constructing models and mathematical representations that reveal the many similarities in how cities are organized and grow. And when we say “grow”, we mean as an organism grows. This is a feature of complex systems. Bettencourt’s introduction says:

This emphasis on the connections between many different aspects of cities —  their built space and land uses, their infrastructure and services, their social life and its outcomes — is the business of complex systems as a relatively new field of scientific inquiry…The integration of ideas and concepts from many disciplines also forces each piece to shift and change as it is constrained and enabled by others into new frameworks.

Some of the key qualities that define cities in this science (and it requires a book to explain them) are property of scaling, presence of networks, energy flows, diversity and neighborhoods. Social aspects are very important in whether a city will be a success (in the sense of serving its populations and attaining longevity).  Michael Batty, whose recent book, Inventing Future Cities, is a philosophical but cogent overview of the science, quotes an earlier author, Lewis Mumford (What is a City).

The city in its complete sense, then, is a geographic plexus, and economic organization, an institutional process, a theater of social action, and an aesthetic symbol of collective unity. The city fosters art and is art; the city creates the theater and is the theater.

So the takeaway is that the city is about its people and their interactions. The more dense the city, the greater frequency of interactions. There are numerous studies showing linear relationships between population and many other outcomes. For some activities, the relation is superlinear (increases more rapidly than merely proportionately). There are hundreds of datasets recorded by numerous authors mapping these relationships. Here is one (Source: Yang et al., Phys. Rev. E 100, 032306). Several relationships are superlinear but one is merely linear.

Because the number of interactions increases with the population, there are numerous outcomes, both positive and negative. We are all familiar with the congestion that comes with increased population density. More people means more cars on the road, more crowds on sidewalks, less room in public facilities. It also means more demands on public resources such as water utilities. But more people also means more business interactions, better availability of some services (transit, for example). Of special interest to the technology culture is the result of intense collaboration (note the increase in patents submitted in the figure).

The question of the impact of density has been studied by many, using historical examples and also collecting contemporary data. Here is a simplified diagram illustrating an overview.

Note that net social benefit increases linearly with density of social interactions until an optimum is reached, then benefit declines until system becomes unstable.

The conclusion from this could be simply stated that growth is beneficial to success of the city, but only to a certain point, and after that is deleterious. How could we predict what this point is for Ann Arbor? There must be metrics that could be considered.


Ann Arbor’s discussion of the current rapid moves in unzoning much of the City has been severely limited, especially as to prediction of likely outcomes. Planning is supposed to indicate the direction that policies we put in place will take us. There is supposed to be some sort of consensus within the community about the outcomes. Typically a comprehensive plan begins with a “vision statement” that serves as a grounding for actions within the plan. Actual implementation is supposed to reflect those outcomes and mechanisms should be in place to achieve them. Here is the vision statement for our last comprehensive plan (n.b., the actual document is called a “Master Plan”, but some members of our community find that to be offensive, so most plans are now referred to as a “Comprehensive Plan” instead. It still means that the Plan is supposed to serve as a template for planning).

“The City of Ann Arbor will be a dynamic community, providing a safe and healthy place to live, work and recreate. It will be a place where planning decisions are based, in part, on the interconnectedness of natural, transportation and land use systems. Natural systems, including air and water, natural features, native flora and wildlife habitats, will be improved and protected. It will be a place where the Huron River is a cherished part of the community and a focal point for recreation. Downtown will continue to be a vibrant part of the community that ties all parts of the city together. Transportation systems will include enhanced opportunities for public transit, extensive opportunities for alternative modes of travel and improved management techniques to reduce the impact of traffic on existing streets and neighborhoods. Land use systems will be compatible and complementary, and will include residential, recreational, commercial, office, educational, institutional and industrial uses, which will provide extensive choices in housing (including low cost housing), shopping, employment and recreational activities. Historically significant buildings and neighborhoods will be preserved. The quality of life in Ann Arbor will be characterized by its diversity, beauty, vibrancy and livability and ultimately will depend upon the positive interaction of these systems.”

It sometimes seems that our only “vision” now is to utilize every square inch possible for residential development, achieving density both by increasing the building envelope footprint (reduction of setbacks) and increased height, and definitely by increasing the number of units per acre. Single-family zoning is under attack, and now (with the TC-1 zoning proposal for W. Stadium) one of our principal commercial service areas is under threat of being directed into a monoculture of tall residential buildings with no real commercial presence. There have been vigorous protests from many sectors of the local neighborhoods but it is uncertain how Taylor’s Planning Commission and his solid Council majority will heed those. What is at risk is a major commercial and service area that serves much of the West Side of Ann Arbor. Are those residents to be ignored?

The premise for the current set of transformative policies has not been explained, except in the most simplistic form. To repeat (again and again) that increase in supply of housing units will eventually, inevitably, result in affordable housing. As Taylor said in the statement already quoted here, “Supply and demand is the law”. (Presumably he means a natural law.) But there is ample reason to contest that conclusion (it will have to be in another post). And the notion has been advanced that anyone who wants to live in Ann Arbor should be able to find housing here. But that suggests that Ann Arbor is infinitely expansible. Is it growth for its own sake? To attain some social goal? (Sometimes the suggestion is made that this will advance racial equity, but the mechanism is unclear.) Does Ann Arbor have limits, other than the obvious one of our fixed border? What are the limits of density before the city becomes unlivable or even dysfunctional?

I wondered whether our Planning Department was working from a model that had not been explained. So I asked our Planning Director, Brett Lenart, if there were such a model (I didn’t want to put him in a compromising position, so I copied the email to the City Administrator). Here was his answer.

As for mathematical models for City development, the Economic Equity and Affordability Analysis performed by the County in 2015 modeled the needs of affordable housing units in the City, and other communities. The City’s current Comprehensive planning documents reference densities in some areas specifically, and in other indirect ways, lead toward density when discussing outcomes such as increased transit mode use, which becomes more possible with increased densities, though not always defined in City planning documents as a specific number.

Another strong policy statement and justification for many changes in configuration of the City, including transportation, is the A2Zero plan. A good deal of the City Budget is aimed at fulfilling this plan. And we have also been informed that there will be a request on the November ballot for a 1.0 mill tax to support these aims. Taylor has been clear that this is a major thrust of his. It is hard to argue with climate change.

Kian Goh, in her book Form and Flow, asks, “In the face of climate change and uneven social and spatial urban development, how are contesting visions of urban futures produced and how do they attain power?” She examines three case studies of urban areas facing issues from climate change. They are New York City, Rotterdam, and Jakarta. In each, “insurgent” community groups rose up to challenge institutional solutions. Her thesis, based in “urban ecology”, is that top-down approaches from “hegemonic” powers are being contested by grassroots community groups, and it is clear where her sympathy lies – and it is not with those engaged in “modernist urban planning”.

“…one aspect remains constant among those in power. There is a strong…belief that there are urban development solutions to climate change problems, if done properly…But how can this be the case when it is those same systems of urban development that created, and continue to perpetuate, those problems?”

Really, in the current efforts by Taylor and his supporters to transform not just the form but the complex and diverse social character of Ann Arbor, one is reminded of the 1950s urban renewal wave that forever displaced and marred neighborhoods in the United States (Ann Arbor, miraculously, escaped). The tools they are using include the threat of climate change, but A2Zero, if examined closely, is simply a framework and defense of growth.

UPDATE: A recent study examined the “supply question” with reference to affordable housing. A common assertion among development advocates has been that increased supply of housing (provided via development) will result in housing being more affordable. This study examined outcomes of upzoning over a broad range of U.S. locations and basically refuted that assumption. This data-dense study is being widely quoted.

Explore posts in the same categories: politics, Sustainability

12 Comments on “Density and Sustainability in Ann Arbor”

  1. Diane argus Says:

    Thank you so much for this comprehensive report to ruminate on. Wish everyone was ad well informed and even a little bit researched

  2. poodlechild Says:

    Thank you, Vivienne, for another clear explanation of what is happening in Ann Arbor and why.

  3. Maurita Holland Says:

    You provided the documentation we’ve been looking for. Thank you so much. Let’s make sure this report has a very wide audience!

  4. Your well-researched work is what we’ve been looking for. Thank you! Now we need to help disseminate it widely.

  5. Patricia L Alvis Says:

    Your observations always add new things to think about in my general interest in urban planning in general and as it is exemplified in Ann Arbor. A couple of specific matters I’m thinking about: One that the “comprehensive” view of the city by the Taylor administration seems unaware of the “university tow” factor. This although clearly the location and design (and rental pricing) rather clearly suggest that as a driver of these dense buildings. Second, why are the buildings so ugly?

    • Thanks, Pat. Actually, I don’t believe that the Taylor administration is currently very much concerned about the influence of the UM in housing, though it definitely informs the property values. Yes, it seems that we are condemned to the “cell block” architecture for most of these large new buildings. I think it has to do with profitability. We have to go onto campus to see anything like graceful architecture.

      • John Smith Says:

        About Taylor & UM, I thought what you said: Taylor does not concern himself with what UM does–he said as much during the last election debates. So, I was surprised to hear that Taylor lobbied the new UM President hard to increase dorm capacity by around 2300 beds on Central Campus. The result is that rental capacity in A2 should increase by around 4%. What do you think about this? I think, if true, Taylor sensed some vulnerability on his political flanks and took some action to head off a perceived vulnerability. He has an absolute majority and so I guess it was safe for him to stick his neck out on this issue. The good news for us is that sometimes the big shots can’t always get what they want! They have to scale back and make concessions. I was publicly hammering Taylor at #a2council (twitter) on not doing anything to push-back on UM so I am glad to see Taylor prove to us all that the City does have some sway with the mighty UM Administration.

      • Thanks, I did not hear that Taylor was involved with the new dorms. That was not mentioned in this news story (no comments).

        I’m very encouraged by the new UM President. Santa Ono has expressed an interest in being involved with projects and goals of joint interest with the City. He responded in a tweet to Robert Goodspeed when he published an op-ed in the Michigan Daily saying that he wanted to engage on this. But I have not seen a notice about Taylor in any of this.

        The new dorms are great! Or will be. It is good news.

      • John Smith Says:

        +Kareninaa was claiming that Taylor was lobbying hard behind the scenes for UM to build some housing capacity on campus. Claimed to have been getting info second hand from insiders. Can we get some verification of this?

      • I don’t know who that is and I have no inside sources.

  6. PeteM Says:

    Interesting post. I realize that you aren’t (to my knowledge) currently in local government where you would have to make these choices, but I am curious you would favor TC-1 zoning in any parts of city (or in none) and similarly if you think A2Zero should or shouldn’t be revised?

    • Yes, correct. I am not currently on any elected or appointed board or committee.

      I thought TC-1 was fine or at least OK for the Briarwood area. It seemed to fit with the general nature of the area and it was my impression that there was consultation with at least a few of the major property owners there.

      Yes, I think A2Zero should be rethought, substantially. Many parts are not really relevant to what is the core goal, it confuses us as to what should be done to address the issue in reality, and the core goal is poorly defined as it is confined to the physical borders of Ann Arbor rather than to any regional effects.

      I am answering your questions though they are not really relevant to this particular post.

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