Tag Archives: Austin

The zoning straightjacket

The more things change, the more they remain the same.

DC is nearing the end of a lengthy process to re-write the city’s zoning code. The re-write is mostly a reorganization, combining overlays and base zones in an effort to rationalize a text that’s been edited constantly over the better part of half a century. While there are a number of substantive policy changes (all good and worth supporting – reducing parking requirements, allowing accessory dwelling units, allowing corner stores, etc.), the intent of the re-write is to look at the structure and policy of the code, rather than look for areas of the city where the zoning classification should change.

Actual re-zoning will require an update to the city’s comprehensive plan (as all zoning changes must be consistent with the comprehensive plan). As promising as the policy changes in the zoning re-write may be, they do not represent any kind of change to the basic city layout – areas currently planned for high density will see more development, and areas zoned for single-family homes will not.

Last year, the District Government and the National Capital Planning Commission worked on dueling reports (see the documents from DC and NCPC) at the request of Congress on the potential for changing DC’s federally-imposed height limit. Leaving aside the specific merits and drawbacks of this law, the planning team needed first to identify areas that would likely see taller buildings if the height limit were to change.

I’ve borrowed the title of this post from Charlie Gardner, to try to show how little room we’ve planned in our cities for change. Even with the perception of runaway development in growing cities, the amount of space that’s set aside for a physical transformation is remarkably small. Zoning is a relatively new force shaping our cities – about a century old. We’re now seeing the effects of this constraint.

Consider the following examples of freezing city form in place via zoning codes:

Old Urbanist – The zoning straightjacket, part II, writing about Stamford, Connecticut:

In general, the zoning maps continue to reflect the land use patterns and planning dogma of the 1920s, with a small, constrained downtown business district hemmed in by single-use residential districts through which snake narrow commercial corridors.

This, if nothing else, seems like a fundamental, if not the only, purpose and challenge of city planning: accommodating population growth in a way that takes into account long-term development prospects and the political difficulty of upzoning low-density SFD areas. In light of this, can a zoning code like Stamford’s, with a stated purpose of preserving existing neighborhoods in their 1960s form, and resistant to all but changes in the downtown area, really be called a “planning” document at all? The challenges that Stamford faces are not unique, but typical, and progress on them, as zoning approaches its 100th birthday, remains the exception rather than the rule.

Better Institutions – Look at the Amount of Space in Seattle Dedicated to Single-Family Housing, writing about Seattle:

Putting aside the issue of micro-housing and apodments, [ed – I wrote about Seattle’s apodments here] what I’d actually like you to draw your attention to is everything that’s not colored or shaded — all the grey on that map. [ed – here is a link to the map] That’s Single-Family Seattle. That’s the part of the city where most people own their homes, and where residents could actually financially benefit from the property value-increasing development necessary to keep Seattle affordable. It’s also the part of the city that’s off-limits to essentially any new residential construction because preserving single-family “character” is so important. And it’s why residents in the remaining 20% of the city can barely afford their rents.

Dan Keshet – Zoning: the Central Problem, in Austin, Texas:

Zoning touches on most issues Austin faces. But with these maps in mind, I think we can get more specific: one of the major zoning problems Austin faces is the sea of low-density single-family housing surrounding Austin’s islands of high residential density.

Daniel Hertz – Zoning: It’s Just Insane, in Chicago, Illinois:

So one thing that happens when I bring up the fact that Chicago, like pretty much all American cities, criminalizes dense development to the detriment of all sorts of people (I’m great at parties!) is that whoever I’m talking to expresses their incredulity by referencing the incredible numbers of high-rises built in and around downtown over the last decade or so. Then I try to explain that, while impressive, the development downtown is really pretty exceptional, and that 96% of the city or so doesn’t allow that stuff, or anything over 4 floors or so, even in neighborhoods where people are lining up to live, waving their money and bidding up housing prices.

Chris D.P. – The High Cost of Strict Zoning, in Washington, DC:

Across town, the Wesley Heights overlay zone strictly regulates the bulk of the buildings within its boundaries for the sake of preserving the neighborhood character.  Is it ethical for the city government to mandate, essentially, that no home be built on less than $637,500 worth of land in certain residential neighborhoods?

The largest concentration of overly restrictive zoning (from an economic perspective) appears to be downtown, along Pennsylvania Ave and K Streets NW. If we value our designated open spaces, and won’t concede the exclusivity of certain neighborhoods, but understand the environmental and economic benefits of compact development, then isn’t downtown as good a place as any to accommodate the growth this city needs?

DC’s height study shows a similar pattern. The very nature of the thought exercise, the hypothetical scenarios for building taller and denser buildings in DC requires first identifying areas that might be appropriate for taller buildings. As a part of this exercise, the DC Office of Planning identified areas not appropriate for additional height based on existing plans, historic districts, etc.

These excluded areas included: all federal properties, all historic landmarks and sites; low density areas in historic districts; all remaining low density areas, including residential neighborhoods; institutional sites and public facilities. Those areas are illustrated in the Figure 4 map below. The project team determined that sites already designated as high and medium density (both commercial and residential) were most appropriate for the purposes of this study to model increased building heights because those areas had already been identified for targeting growth in the future through the District’s prior Comprehensive Plan processes.

Put this on a map, and the exlcuded areas cover 95% of the city: 

DC height act study no go

Now, this isn’t analogous to the comparsions to areas zoned for single-family homes in other cities, nor are all of the areas in red innoculated from substantial physical change. However, it does illustrate just how limited the opportunities for growth are. It broadly parallel’s the city’s future land use map from the Comprehensive Plan, where large portions of the city are planned for low/medium density residential uses (click to open PDF):

DC Comp Plan Future Land Use

The plan’s generalized policy map also illustrates the extent of the planned and regulatory conservation of the existing city form (click to open PDF):

DC Comp Plan General Policy

The areas without any shading are neighborhood conservation areas.

All of this should be reassuring to those concerned about the proposed zoning changes, since all changes must be consistent with the comprehensive plan.

More on the geometry of transportation: “Transport is mostly a real estate problem”

In June, the Urbanization Project at NYU’s Stern Center posted several graphics looking at the space devoted to transportation in our cities. As the author, Alain Bertaud, frames it, “transport is mostly a real estate problem.” That is, different transportation modes require different amounts of space to accomplish the same task.

Comparison of population/employee density and street area per person. Image from NYU Urbanization Project.

Comparison of population/employee density and street area per person. Image from NYU Urbanization Project.

Each of the selected examples cluster around the diagonal blue line, representing an average of 25% of a city’s land devoted to streets.

Percent of land use devoted to buildings, streets, etc. Image from NYU Urbanization Project.

Percent of land use devoted to buildings, streets, etc. Image from NYU Urbanization Project.

Two observations: the 25% pattern is remarkably consistent; as is the geometric relationship between modes of transport and the intensity of land use.  The green horizontal lines show how much space a car uses at various speeds – the faster the car goes, the more space it requires. A parked car occupies 14 square meters, while one moving at 30 kph takes up 65 square meters.

The obvious corellation is between a city’s density and its type of transportation network. Cars take up a large amount of space relative to their capacity, and a transport system based on cars alone cannot support a great deal of density.

Alex Tabarrok frames this in terms of “the opportunity cost of streets.” While there is certianly an opportunity cost to various street uses, it’s worth noting that some space must be devoted for streets in order to access property. Charlie Gardner at Old Urbanist takes note that the role of streets is not solely about transportation:

In addition to their transportation function, streets can also be understood as a means of extracting value from underserved parcels of land.  The street removes a certain amount of property from tax rolls in exchange for plugging the adjacent land in to the citywide transportation network.  Access to the network, in turn, increases the value of the land for almost all uses.  For the process to satisfy a cost/benefit analysis, the value added should exceed that lost to the area of the streets plus the cost of maintenance. (This implies rapidly diminishing returns for increasingly wide streets, and helps explain why, in the absence of mandated minimum widths, most streets are made to be fairly narrow.)  For many of the gridded American cities of the 19th century, as I’ve written about before, planners failed to meet these objectives, although these decisions have long since been overshadowed by those of their 20th century successors.

Charlie also notes that many great, dense, walkable cities around the world devote about 25% of their land to streets, yet many American downtowns use a much higher percentage of their land to streets.

Some of those numbers might depend on the exact method of accounting. While Charlie’s estimate for downtown DC shows 43% of the land used for streets, DC’s comprehensive plan shows approximately 26% for the city as a whole:

Land Use Distribution in DC, from DC's 2006 Comprehensive Plan.

Land Use Distribution in DC, from DC’s 2006 Comprehensive Plan.

The graphic doesn’t specify if the street figure refers to street right of way, or just the carriageway portion of the street, but not the ‘parking area.‘ Seattle’s planning documents also showa similar pattern: 26% of land city-wide used for streets, but also a higher percentage of downtown land devoted to streets.

Seattle land use distribution by neighborhood. Image from Seattle's 2005 Comprehensive Plan.

Seattle land use distribution by neighborhood. Image from Seattle’s 2005 Comprehensive Plan.

The Seattle calculation looks at land devoted to right of way for streets, rather than just impervious surface.

Making better or different use of existing right of way is one thing; however, once that right of way is set, it is very difficult to change. Transportation networks awfully path dependent. Chris Bradford looks at Austin’s post-war planning and the abandonment of the street grid – path dependence in action:

Back then, “planning” chiefly meant “planning streets.” It’s a shame that planning lost that focus. The street grid that permeated Austin in 1940  is of course still with us, and forms the backbone for a number of quite livable neighborhoods.

So what happened? Developers building large, planned subdivisions (Allandale, Barton Hills) continued to add decent street networks after 1940. But the City itself appears to have gotten out of the grid-planning business not long after this map was made…

Collectively, these could and should have been platted into 40 or so city blocks. Instead, they remain two big blobs of land. The lack of connectivity funnels traffic onto South Lamar and Manchaca; impedes east-west mobility, dividing eastern and western neighborhoods; forces people to make circuitous trips to run even simple errands; and forecloses any sort of low-intensity, mixed-use development in the area. Then there’s the sheer loss of public space: South Austin should have a few more miles more of public, connected streets than it has today.

Once the street grid is set, it is very difficult to change.