Saturday, March 21, 2015

Single Family Zoning: It's All About the Lot Sizes

Contemporary critiques of zoning take several forms.  First, and probably most common, is the critique of strict use segregation in the Euclidean manner, with commercial and residential areas segregated to greater or lesser degrees.  An increasing focus has lately been placed on the relative preponderance of single-family detached residential zoning within urbanized areas.  A third line of critique, which has received somewhat less attention although it has been the subject of numerous academic studies over the years, looks at minimum lot size requirements within both single-family and multifamily zones.

Although it may seem like a minor subject next to the first two critiques mentioned, the second critique is incomplete without examining permitted lot sizes.  For instance, even though a city may have substantial areas set aside for multifamily housing, if the minimum lot size per apartment unit (or floor area ratio equivalent) is approximately equivalent to single-family zones, the density and/or affordability difference may be minimal.  Alternatively, the single-family detached ("SFD") zoning designation, by itself, tells us little about the density of the area.  Depending on the lot area required and right-of-way widths, SFD densities for a given household size can range from 300/square mile to as much as 25,000/square mile or more, all without the need for any party walls.  

A few concrete examples can help illustrate the point.  In the American context, despite the presumed consumer preference for SFD homes, neighborhoods of homes on very small lots and using narrow rights-of-way, such as are abundant in many other countries, are quite rare.  In the entire New York metropolitan area, for instance, there are only a handful of such neighborhoods, mostly those intended as beachside retreats along the southern shore of Brooklyn and on the Rockaway Peninsula.  One such neighborhood is shown here:


This is Gerritsen Beach, in Brooklyn, showing parcels of 1,800 square feet on a right-of-way (property line to property line) of 28'.  The 2010 Census gives a population density of over 17,000/square mile, about half of the average for Brooklyn, although this may be affected by the presence of second homes.  As Nathan Lewis has shown, similarly scaled neighborhoods in Tokyo attain densities exceeding 30,000/square mile.  Even so, it is about 80% denser than the densest SFD suburbs built in Nassau County during the 1940s-1970s.  It is more than twice as dense as Levittown itself, and denser even than the three-decker neighborhoods of cities like Worcester, MA or New Haven, CT.  The New York metro area has a conspicuous absence of neighborhoods of this density and type, with Census tracts swiftly falling off from around 25,000/square mile to 10,000/square mile.

Beach neighborhoods seem to be popular settings for this type of design, as a similar (but slightly lower) density is present in Long Beach, California, shown below.  Lots are around 2,400 square feet with a 40' right of way and alleys of 13' (comparable density appears to be achieved through presence of small apartment buildings):  


And here is Levittown itself, with lot sizes of around 6,000 square feet and right-of-way (between outer sidewalk edges) of 50'.  Population density is approximately 7,500/sq. mi.:  


The Levittown homes in their initial form, intended for the large families of the Baby Boom era, were actually somewhat smaller (800 sq. ft.) than the 1920s vacation cottages of Gerritsen Beach (1,000 sq. ft.).  The contrast of very small houses with lots the same size or larger larger than those typical of the pre-1940 period seems to have been characteristic of the time period, perhaps related to the increased cost of labor following the Great Depression combined with stable land values.  The more spacious lots may have offered some compensation for the modest interiors.

At the extreme is the ultra-low density of interior but non-rural New England, showing 2- and 3-acre lot zoning (here, in Easton, Connecticut), accompanied by wetlands regulations, with population density of around 260/square mile:


Now, if a rapidly urbanizing country wished to offer the possibility of ownership of a SFD home to the greatest possible portion of its population, the obvious policy goal would be to allow construction of a SFD home on any size lot desired, and on streets as narrow as possible so as to minimize economic waste.  The result is very much what we see in most of the wards of Tokyo as well as in Gerritsen Beach: very small lots but with practical (square-shaped) dimensions along narrow streets and no alleys.  Where multifamily buildings are not prohibited, these will be interspersed here and there, sometimes occupying two or three lots.

In practice, however, American zoning does not take this approach, with the sole exception of mobile home parks (which I've discussed here).  Not only are lot sizes strictly regulated for SFD zones, generally to standards far in excess of what is needed for a comfortably-sized home, other policy measures are in place that make small lots difficult to build as a matter of economics, such as:
  • Apparent aesthetic preference for large, widely space multifamily over densely packed single-family in multifamily zones.  Although small multifamily buildings have fallen out of zoning fashion, if they were ever popular, those zones that survive have some curious features.  For instance, one Connecticut town's code, typical of the type, effectively grants density bonuses for building duplexes and triplexes over building two or three standalone houses on the same lot.  In the densest zone it is possible to build a single-family home on 5,000 sq. ft. -- the smallest SFD lot permitted in any zone -- but a duplex requires only 7,500 sq. ft. and a triplex only 9,000.  The policy intent here is not obvious, but implies aesthetic favoritism for retaining large dwellings with generous spacing even at the expense of the single-family ideal.  
  • Minimum street widths.  Although these do not affect the lot size directly, mandated wide streets make small lots for SFD a less economical proposition.  For instance, were the Gerritsen Beach lots placed along the Levittown right-of-way, each 1800 sq. ft. lot would look out onto 3,000 sq. ft. of sidewalk and roadway!  The neighborhood, overall, would have a ratio of 1.2:1 of private land to right-of-way, or, in other words, only 55% of the land would be in private lots for sale.  Levittown's ratio is a far better 3:1.  With a 28' right-of-way, Gerritsen Beach's streets are already about as wide as economically possible in light of high land values, and streets of Japanese dimensions would yield a far better ratio.
The design differences produce some noticeable differences even at the very large scale.  The prefecture of Tokyo, with population 13.2 million, has a homeownership rate of 45%.  The city of New York, with population 8.4 million, has homeownership of 32%.  Although the prefecture's density is lower than New York's (16,000 vs. 28,000/sq. mi.), Tokyo's outer suburban areas are so much denser than New York's that its metropolitan area density is higher.  For the entire metro area, Tokyo maintains a 56% homeownership rate with 47% share of detached houses, as compared to New York with 52% homeownership and 36% SFD share.  Los Angeles, to pick another example, has 49% homeownership with 50% SFD stock.

A metro area of more comparable size to New York's, such as Kyoto-Osaka-Kobe, has a homeownership rate of 58%, higher than the entire state of New York, and not much lower than far smaller American cities commonly associated with low-density SFD housing such as the Houston MSA (60%), Dallas (61%), Atlanta (63%) and Phoenix (63%).

Interestingly, the issue of minimum lot sizes appears to be one on which there is general agreement between the Smart Growth faction and the defenders of suburbia, as Wendell Cox wrote some years ago in response to critique from the Brookings Institute:
"I was even more surprised at the claim that I defend 'anti-density zoning and other forms of large lot protectionism.' Not so. 
Indeed, I agree with [Jonathan] Rothwell on the problems with large lot zoning. However, it is a stretch to suggest, as he does, that the prevalence of detached housing results from large lot zoning. This is particularly true in places like Southern California where lots have historically been small and whose overall density is far higher than that of greater New York, Boston, Seattle and double that of the planning mecca of Portland."
I think that Cox is correct here, but not even as correct as he could be.  Large-lot zoning not only does not cause a prevalence of SFD housing, it limits it, as shown in the New York metro area.  Los Angeles' metropolitan density is substantially higher than New York's (a point often raised to incredulous reaction), but its share of SFD stock is much higher.  To point out in response to an allegation that a city is heavily zoned for SFD that a majority of its housing units are in multifamily structures (in the case of Seattle, at the link) only underscores the point.

Although most studies have found that minimum lot sizes do affect overall development density (that is, developers appear to build at or near the minimum lot size allowed), one study of Maryland suburbs of Washington, D.C. found that, except in the case of areas with very large minimum lots sizes, developers were subdividing into lots larger than the mandated minimum, including in cases where planned unit development options left them with a free hand to build denser than the zoning code superficially allowed:
"We then examine the extent to which lot size is being constrained by regulation by comparing actual subdivision density to the allowable density under zoning rules. This analysis is done for three counties with different degrees of suburbanization. We find that only in the areas with the very large lot zoning does zoning seem to be constraining actual lot[] size. There is a good deal of excess capacity in the density that could be built, especially in the more densely zoned areas." Lot Size, Zoning, and Household Preferences:Impediments to Smart Growth?
There might be no concern with low-density development at the fringes of metro areas except that such areas, once built up, are politically almost impervious to change.  Some cities have implemented maximum lot sizes, but these are generally very generous and only apply in certain areas.  The misunderstood achievement of the New Urbanism, and the Maryland suburb of Kentlands in particular -- whatever its faults in design detail -- was that small lot single-family housing developments not only need not be qualitatively inferior to the 6,000+ sq. ft. tracts that characterized the post-1940 suburban era, and that they could even offer amenities that made them superior residential environments.  Where regulatory mandates fail, leading by example can succeed.

Kentlands, with SFD lots from 5,600 to 2,600 sq. ft, and with ROWs ranging
from 45 ft. to 12 ft. on alleys.
Related posts: None of mine, but Nathan has written several great pieces on the topic which you can find at his website.

Sunday, March 8, 2015

Auto Costs and Housing Costs, or, One Reason the Suburbs are So Appealing

Simon Vallee has a post from some time back about filtering vs. gentrification in which he analogizes the process of gentrification, in North America, to the car market in Cuba, noting that restrictions on supply will tend to boost prices and limit availability of a desired good.  Although the comparison is intended to be illustrative, I think it also highlights a substantive difference which, in effect, subsidizes automobiles at the expense of housing.  First, though, some background.

Going back for a moment to the subject matter of a Nathan Lewis post, we can note that, land costs aside, the sticker price of manufactured housing as compared to a new vehicle is not as great as one might think.  A two-bedroom manufactured home, for instance, of about the size of the average new home of the 1950s, costs only around $41,500 as compared to the price of a popular new sedan (I chose the Altima, one of the best-selling cars in the United States) at around $27,000:


However, when car costs are compared to overall home values, including site-built as well as manufactured homes, a different story emerges.  In 1940, the median home was valued at only 2.3 times the retail price of the average new car.  By 2010, in spite of the crash in home prices, this ratio had risen to 6.4.  Car operating costs have also generally fallen as fuel efficiency and vehicle reliability have improved.  Median rents, not shown here, have grown at an even faster rate than home values.

In short, over the last seven or so decades, car ownership (or leasing) has become dramatically less expensive relative to home ownership or tenancy.  Partly this must be due to labor-saving technologies that have affected car production more than homebuilding: even manufactured homes still require extensive human labor, which has become much costlier (though more productive) since 1940, whereas the formerly labor-intensive car assembly process has been heavily automated and accelerated.  The process of robotically assembling houses, or even apartment buildings, remains in its infancy.

Are long-term, over-inflation increases in home values also linked to increases in land values caused by general urban population increase and restrictive zoning?  It goes without saying that rural land values are lower than urban land values, and the Census homeownership figures show that housing values are lower, and homeownership higher, in more rural states in spite of lower incomes.  Relatively poor and rural West Virginia has the nation's highest homeownership rate, while 100% urbanized Washington D.C. has had its lowest in every Census since 1930.  As Luis Bettencourt writes:
"There are several important consequences for general land use in cities. First, the price of land rises faster with population size than average incomes. This is the result of per capita increases in both density and economic productivity, so that money spent per unit area and unit time, i.e. land rents, increases on average by 50% with every doubling of city population size! It is this rise in the price of land that mediates, indirectly, many of the spontaneous solutions that reduce per capita energy use and Carbon emissions in larger cities. Cars become expensive to park, and taller buildings become necessary to keep the price of floor space in pace with incomes, thus leading to smaller surface area to volume."   The Kind of Problem a City Is.
Urbanization in the era of the automobile in turn causes frictions which lead to pressure for zoning.  American municipal zoning, in its initial formulation and as is still practiced today, is fundamentally a device to politically manage these frictions by restricting the intensity of residential land use.  Though not its stated purpose, it has the effect of increasing land scarcity that is already inherent in the urbanization process, and thereby provides a positive feedback mechanism that puts additional pressure on housing values.

What does this all have to do with cars?  As noted above, the cost of a manufactured home, in isolation, is only slightly more than that of a typical sedan.  As urbanization increases, however, the increasing value of land makes cars, which do not have their land storage cost bundled into the sticker price (unlike Japan does, effectively), seem like a relative bargain.  Some time ago, Cap'n Transit wrote a fascinating series on how New York came to tolerate and eventually permit free overnight on-street parking in the late 1940s and early 1950s.  We would find it ludicrous if someone were to purchase a manufactured home and to drive it into Manhattan on a flatbed expecting the city to provide free land on which to site it, but that was how the story went with cars:
"This [middle-class] conception of the benefits of car ownership has always had a huge bait-and-switch component to it. In New York City in the 1940s it was no exception. When people looked at the price of a car, they didn't figure in $20-35 per month in garage rental. When they got their cars, many couldn't afford to pay and took their chances on the street. Garage owners now had to compete with free street parking and lowered their rates accordingly, which meant that they didn't have enough income to expand their facilities, and resorted to bribing the police. 
"These social-climbing drivers felt cheated, but they didn't take their anger out on the car dealers. No, they felt that the city owed them the free parking necessary to make their cars as affordable as they thought." The right to free parking in 1940s New York
There are therefore two clashing trends: as cities grow in size, the cost of a buying a car declines relative to increases in income and housing cost, yet the actual cost of storing a vehicle is, or should be, increasing rapidly, since cars, like houses, occupy a significant amount of valuable space.  Rather than taking the common-sense Japanese approach of the shako shomeisho (proof of parking), however, American states and cities have engaged in onerous mandatory inclusionary zoning for cars (parking minimums), zoning exemptions (e.g. not counting garages toward FAR limits and allowing parking, but not housing, in mandated setbacks), tax exemptions (only 16 states maintain a personal property tax that covers automobiles) and fringe benefits (the commuter parking benefit), in addition to rent-free public housing for cars (overnight on-street parking).  Whereas in 1940, buying and operating a car to escape urban housing costs simply shifted the balance of expenses, with a car costing almost half as much as the median home, in 2010 the prospect of doing so was much more economically feasible.  No doubt many of those New Yorkers of the 1940s and 1950s eventually drove those cars out of their subsidized parking spaces and off to the far reaches of Nassau, Bergen and Westchester Counties, and who could blame them?

Perhaps the biggest effect of all though, going back to the beginning of the post, relates to the obvious but important point that while housing production, and particularly in-city housing production, is subject to political constraints, car production is not (well, mostly not).  There even seems to be a difference in Americans' moral characterization of those who build homes and cars for profit: while a search for the phrase "greedy developers" returns over 60,000 hits, "greedy automakers" returns only 1,000.  From that perspective, the so-called "drive 'til you qualify" phenomenon, much questioned and criticized, is an entirely reasonable response to this economic reality, particularly given widespread lack of highway tolls. 

Making a full accounting of the political choices that have been made with regard to both housing and transportation is a daunting task, but it does help illuminate the residential patterns we see without the need to resort to moral judgments about those choices.

Related posts: Was the Rise of Car Ownership Responsible for the Midcentury Homeownership Boom in the US?

Saturday, January 24, 2015

Sonia Hirt on the Origins of American Zoning

I've written about Professor Sonia Hirt's work previously, so I was glad to find out several months ago that she had a forthcoming book, Zoned in the USA: The Origins and Implications of American Land-Use Regulation, which would address in detail some of her (and my) major research interests.  Hirt, who received her architectural training in Sofia, Bulgaria before earning a PhD in planning at the University of Michigan, has set out to answer the question which has plagued her since shortly after her arrival in the United States in the early 1990s, when she first encountered an American zoning code:

"How could Americans, whose reputation for being independent and freedom-loving and respecting private property was worldwide put up with such tedious laws governing the building of their everyday environments and way of life?"

The question has been examined before, though perhaps not as directly, and Hirt's citations include many prior books and studies that I have also discussed on the blog, including Robert Fishman's Bourgeois Utopias, Jonathan Levine's Zoned Out, Robert Fogelson's Bourgeois Nightmares, Kenneth Jackson's Crabgrass Frontier, Robert Fischel's papers on zoning and many others.  Even Spiro Kostof and Besim Hakim (who has a new tome of his own focusing on Mediterranean urbanism) receive prominent mentions as Hirt surveys some 4,000 years of land-use regulation reaching back to Hammurabi.  Apart from addressing the question above, another of Hirt's major contributions with the book is to provide a broad-scope land-use comparison between American land-use laws and the laws of several other developed countries, including France, Germany, Great Britain, Russia, Sweden, Japan and Canada.

One of Hirt's conclusions, that the United States is the only developed country of those surveyed, apart from Canada, to widely employ single-family detached residential zones that bar all commercial and multifamily uses, was anticipated by her previous work.  An equally important finding, in my opinion, is that the United States is the only country of those surveyed that does not conduct land use at the national or state level.  Although the federal government and certain states have dabbled in land-use law with housing anti-discrimination policies and anti-snob zoning statutes, and a few (such as Oregon) have delved more deeply into regional planning, there is no national land-use law (despite the federal government owning 650 million acres of land) nor does any state prescribe zoning categories that municipalities must follow.  Hirt also surveys a wide range of US zoning ordinances and finds little evidence that, despite the zoning reforms of the past 20 years, including the emergence of form-based codes, there has been any revolution in American zoning practice either in substance or procedure.

How this exceptionally American land-use system came into being during the late 1800s and through to the 1930s is the primary focus of Hirt's book.  In chronicling this period, many apparent paradoxes present themselves: for instance, although the United States of the late 19th century prided itself on being the most democratic nation in the world, its citizens had a low level of trust in their elected municipal officials.  The progressive municipal reformers of the time might therefore have campaigned for planning to be guided by state or federal governments, but instead pushed for non-discretionary municipal-level zoning.  As Hirt observes, zoning reformers such as Lawrence Veiller argued that "zoning rules should vary as little as possible in districts that were as large as possible and that zoning relief should be granted only under a very limited set of circumstances, if at all."

But if the planning powers were delegated from state to city, and the city was to have little power to alter the apparently infallible choices of the initial zoning commissions, who was left to actually engage in city planning?  No one, as it turns out.  Planning commissioners were seemingly intended to be little more than curators of the city zoning map, and Hirt finds, as I have also noted, that zoning maps have changed relatively little in their basic allocation of space since the 1920s.  As I've written about before, the actual policy that zoning was intended to serve was almost an afterthought, and was primarily concerned with protecting the investments of wealthy homeowners.  By default, and perhaps unintentionally, city planning (to the extent it existed at all) was turned over to the emerging highway engineering profession.

American zoning policy, in sum, was a negative and reactive vision -- through its implementation, it viewed cities as incapable of honest and effective self-government, and by its actual regulations, it viewed urbanization as a threat to not only investments but to civic spirit and even the American way of life itself. As Hirt writes, "[t]he single-family home had the right to the city: it was always seen as being there first. It was the gracious host, the delicate victim, and the original citizen that was always haunted, followed, invaded, and taken advantage of by other housing types." In this sense, Hirt's book echoes the conclusions of Steven Conn's recent Americans Against the City: Anti-Urbanism in the Twentieth Century.

Has the American zoning system secured the benefits promised by its proponents?  Hirt crunches the numbers and finds that the United States is distinct among Western nations neither in its rate of ownership nor its proportion of single-family homes (see below chart).  Australia beats the US at its own game, having a higher levels of both detached and attached single-family homes with higher homeownership, despite even higher rates of urbanization.  Hungary, with almost identical proportions of attached and detached single-family housing, has much higher homeownership.   Interestingly, the chart shows no correlation whatsoever between proportion of single-family homes and the rate of ownership.  The emergence of the condominium form of ownership, unanticipated by the zoning proponents of the 1920s, appears to have severed the link between detached homes and the homeownership rate.

Source: Hirt (2014) and Japan Statistical Yearbook 2013.
The American achievement appears to be the high proportion of detached single-family homes, which on this chart is behind only Australia, Croatia and Hungary, as well as the size of those homes.  Hirt cites evidence from Fischel's work that, to me, shows that American focus on legal protections for the detached home form may have actually impeded growth in the homeownership rate by establishing excessively large minimum lot sizes.  In Japan, by contrast, families are able to purchase slivers of urban land, which enables robust single-family homeownership levels in an intensely urbanized country.  The same is true in Mexico, where homeownership, overwhelmingly of attached homes, is around 80%.

It appears that, in the United States, despite rhetoric to the contrary, the exclusionary principle and the notion of ownership as investment are (or have become) the primary concerns of local planning and of national housing policy and finance rather than promoting homeownership.  Those policies, though, are beyond the scope of Hirt's book and this post as well.

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Related posts:

Saturday, November 1, 2014

Reconciling Bridges and Urbanism

Bridges have been a feature of urban design ever since King Nabopolassar spanned the Euphrates River with a causeway around 620 B.C, joining together the two halves of the city of Babylon and much later inspiring the title of a Rolling Stones album.  That this innovation represented a major improvement over the ferry transportation that had formerly prevailed was evident to ancient observers such as the Greek historian Herodotus, who noted that "under the former kings, if a man wanted to pass from one of these halves to the other, he had to cross in a boat; which must, it seems to me, have been very troublesome." 

If the transportation advantages were clear at the time, the design challenges of incorporating bridges into a dense urban fabric presented difficulties that have continued to the present day.  Apart from engineering challenges, the primary contextual concern is that a bridge high enough to avoid obstructing the flow of maritime traffic will typically be higher than the city itself, with the result that approaches to the bridge, if they are to accommodate wheeled traffic, will need to extend deeply into the city.  Long approaches, however, disrupt and divide the urban fabric, undermining the very connectivity that the bridge was intended to provide.

For a well-known example, consider the Brooklyn Bridge, which was built to a height sufficient to accommodate the masts of sailing ships that still plied the East River in the early 1880s, and which, like Nabopolassar's bridge, replaced ferry services.  An engineering marvel, the bridge was nonetheless so massive that its approaches reached deep into the heart of Manhattan, overshadowing many blocks and requiring the demolition of others:

The Brooklyn and Manhattan bridges circa 1916. Source.
Built some years before Robert Moses was even born, the bridge represented the first instance of an elevated roadway carving a swathe through a built-up area of Manhattan and dividing parts of the city from each other.  In the years since the bridge was built, access ramps from the FDR Drive have further expanded the initial scar, leaving a gap of 360 feet in the city's fabric with limited crossing points.  Although the arch spaces under the approach were creatively rented out as storage space for wine merchants (the bricked-in warehouse spaces can still be seen today), the effect on the immediately surrounding neighborhood could hardly have been a great positive.  The area sliced up by the approaches to the Brooklyn, Manhattan and Williamsburg Bridges became notorious as Manhattan's Lower East Side, and was some decades later subjected to some of the most intensive urban renewal in the city.  

In Europe, where watersheds tend to be smaller than those of North America, major rivers narrower and where many bridges had been built long before the advent of suspension or steel-frame technology, a much more complementary design has long prevailed.  Rather than sending approaches deep into the urban fabric, European cities tend to raise masonry embankments directly against the river, allowing a bridge even of substantial height to discharge traffic directly onto riverfront streets.  Bridges were also considered architectural works in their own right intended to be experienced on foot, and incorporated sidewalk lighting, statuary, benches and other pedestrian amenities.


Pont Neuf, Paris. Google Maps.


Bird's eye view of another Pont Neuf, in Toulouse, with its entry point flush with a
 25-foot embankment providing flood protection against the Garonne River. Bing Maps. 
Running along these embankments at just above water level are often found quays, which formerly served the shipping trade but which today have been converted to car expressways or recreational areas for cyclists and pedestrians (a notable conversion from the former to the later has recently taken place in Paris).

In some famous instances, the city itself extended out onto the bridge, turning transportation infrastructure into a bustling city street with shops and homes.  Among the best known of these are the former London Bridge, the Ponte Vecchio and the Rialto Bridge in Venice:


Pont Notre-Dame, Paris, depicted 1756. Source.
Paris seems to have had several such bridges as well, but most had their houses torn down in the late 1700s when the spatial demands of wheeled traffic began to make themselves increasingly apparent in the larger cities of Europe.  The Pont Notre-Dame, above, was scraped clean of its tall dwellings in 1782, and the centuries-old bridge itself was replaced in the 1850s.  London Bridge's houses, apparently allowed onto the bridge as a means of producing rent to offset the cost of bridge construction in the medieval period, were removed in the late 1750s at great expense to improve the bridge's level of service.  The trend toward retrofitting cities around the needs of wheeled traffic would steadily accelerate through the late 20th century.


Source: Old Urbanist.
Some North American cities have bridges in approximately the European fashion, particularly where the city is located on a bluff overlooking a river or where the river is relatively narrow.  Chicago, Milwaukee and San Antonio, in particular, have numerous such bridges over their relatively narrow rivers, and Austin has partial embankments overlooking a riverside trail.  Des Moines, also, has a series of very European-looking bridges.  Even if geography requires a bridge to enter a city at height, however, that does not mean that integrating it into the city need be impossible.

For instance, even if the ground level cannot be raised to meet the bridge, buildings themselves may be constructed up to the bridge level.  The photo at right shows this approach deployed along a Danube River bridge in Regensburg, Germany (actually, in this case, I believe the bridge may have been constructed to align with the second floors of existing apartments).  With this method, similar to the built-upon bridges described above, the bridge adds a second linear dimension to the city rather than simply being a passive structure accessible only at its endpoints.  

Additionally, the long approaches themselves are demanded only by wheeled traffic.  Where a bridge serves only foot traffic, it is possible to provide high clearance, even with masonry construction, and yet have little or no landward approach.  This method was employed abundantly in the towns and cities of pre-modern China, such as Wuzhen, below, where although the bridge appears to rise very steeply, the grade is quite a bit less than in the standard staircase, and the climb less arduous:


Source.
Steep automobile bridges are possible, but rarely seen, as in this example from Matsue, Japan, which fortunately has a fairly mild winter climate:


Source.
The American approach, reflective of the era of Heroic Materialism in general, has typically been to see bridges as engineering projects first, architecture second, and an integrated part of the city third, if at all.  Even where existing bridges with lengthy approaches have been converted to pedestrian use, long approaches are typically retained, or in some cases, even rebuilt.  

The Big Four Bridge in Louisville, Kentucky, a rail bridge over the Ohio River which had its long approaches removed in the late 1960s, leaving only the central span, was inexplicably rebuilt with approaches even though it was intended primarily for pedestrians (a much simpler plan requiring no land acquisition which would have involved a ramp directly around the final bridge pier was apparently rejected).  On the Kentucky side, pedestrians must ascend a massive, circuitous and over-engineered ramp to reach the bridge:  


Google Maps/Shawn Conn.

A switchback staircase leading directly to the bridge pier was present during construction for the convenience of workers according to Streetview imagery, but seems to have been removed now that the approach is complete!

Nashville's downtown Shelby Street Bridge, which never had its approaches demolished prior to its pedestrianization in the early 2000s, took a more sensible approach of adding a steel staircase and elevator, thereby taking advantage of the tremendous spatial efficiencies of pedestrianism while allowing people with bicycles, strollers or in wheelchairs to reach the bridge: 


Google Maps.
In a first step toward directly integrating the bridge roadway with the surrounding buildings, the bridge and elevator are attached by an elevated walkway to the office building at the left.  It is difficult to overstate the effect pedestrian infrastructure like this contributes toward making the bridge feel like a place, rather than an obnoxious intrusion into the life of the city.

Turning bridge design away from the Heroic Materialist model of bridge-building toward a more pedestrian and city-oriented perspective is a long-term process that appears to be underway with bridge conversions, but many positive changes can done incrementally.  Providing pedestrians with shortcut access points to bridge approaches, linking the bridge surface directly to surrounding buildings and even considering construction of new buildings flush with or underneath the bridge, can all help turn bridges into more than simply impressive engineering feats.

Related posts: Jarrett Walker has a similar take on urban viaducts here (h/t to commenter Marc), and of course these observations could also be applied to other forms of elevated infrastructure to greater or lesser degrees.

Saturday, October 4, 2014

Housing Innovations in Texas

Citylab recently posted an interesting profile of a new development in Harlingen, Texas by Amanda Kolson Hurley.  Having written about this area of the country earlier this year, I was curious to take a closer look at the development, which appeared to take some design cues from the Mexican urbanism that is just a short ride away from this border region.

An aerial view of the development, La Hacienda Casitas, shows it set among mobile home parks that are very common in Harlingen.  These homes, however, are site built, and use lots as small as 1,800 square feet, which is similar to the lots sizes found in the new developments of Matamoros, Mexico.  Streets range from 16 to 22 feet wide, with some on-street parking:


The more I looked around Harlingen, the more this particular development stood out: overwhelmingly, new development in the city consists either of mobile home parks or much larger suburban homes of the type found in sunbelt cities across the United States.  It was a pattern I'd seen before, in Bradenton, Florida, where the city's zoning code divided single-family housing into two types: large lot, site-built suburban and small-lot, manufactured and/or mobile.  Could land use in Harlingen be governed by similar provisions?

Fortunately, the city puts its zoning ordinance and map online in an easy-to-navigate format, so finding residential lot minimums was not difficult:


Here we see that Harlingen, like Bradenton, establishes a minimum lot size for lots in mobile home parks that is less than half that required in the single-family "R1" zone.  In fact, the ratio between the two zoning categories is nearly the same in both cities (Harlingen: 6000/2400 = 2.5 vs. Bradenton: 7200/3000 = 2.4).  Unlike Bradenton, Harlingen does not seem to establish minimum sizes for the dwellings themselves, although setback and lot coverage requirements impose effective maximums that are most restrictive on very small lots.

How well the city holds developers to the limits I cannot say for sure, although most lots in developments platted within the last 20 years appear to be between 6,000 and 7,000 square feet. On first blush the "Planned Development" zone appears to provide some flexibility, but it requires the developer to own a parcel of at least five acres, leaving it unavailable to small-scale builders designing infill projects.  Townhouses are also an option, but are not permitted by right in R1 zones.

In any event, the disparity between zones again appears to create a binary pattern of real estate prices, with new site-built homes on large lots averaging around $145,000, and manufactured homes only $45,000 or so.  Thanks to zoning-abetted filtering*, some site-built homes can be bought for no more than $60,000 to $70,000, but these tend to be of very low quality or on much smaller lots that seem to have been grandfathered in under the present zoning code.  This mandated land consumption obviously contributes to a low-density pattern of urban growth, and also illustrates how zoning's affordability and quality of life impact isn't limited to large coastal metros.  Harlingen's affordability safety valve, the mobile home district, establishes what is in effect a physically segregated zone for low-income, market-rate housing where even the homes themselves are forbidden from being site-built.

Homes in La Hacienda Casitas. Credit: bcWorkshop.
In light of all this, was the La Hasienda Casitas project an attempt to circumvent the code with a development of houses on tiny lots and narrow streets, thereby making occupancy (the homes appear to be rentals, at least for now) of new, freestanding and site-built homes available to low-income families of Harlingen?  Kolson Hurley's article discusses the intensive coordination and grant-seeking between and among architect bcWorkshop and non-profit housing developer Community Development Corporation of Brownsville needed to bring the project to fruition, but I have to wonder whether regulatory barriers, rather than anything inherent in the design and construction of this project, is what is standing in the way of adoption of the style by for-profit developers.


*Zoning-abetted in that the restriction of centrally-located lots to single-family use effectively caps land values, allowing the physical deterioration of the housing stock to play the predominant role in establishing property values.

Related posts:
Mobile Home Impediments and Opportunities
Cross-border Urbanism: From Texas to Tamaulipas

Sunday, August 31, 2014

Demise of the Duplex

The New York YIMBY website has complied Census building permit data to reveal how construction of single-family and small multifamily dwellings in New York City's five boroughs has plummeted since reaching a peak in 2004.  Of the potential explanations advanced for this collapse, contextual downzoning appears to the most likely to me, as the decline began four years before the peak permit year of 2008.  In general, however, small multifamily buildings have widely fallen out of favor not only in New York but across the country over the past thirty years and more.

Using the same Census data, this time calculating for all 50 states and the District of Columbia, it can be seen that small multifamily dwellings (those with between two and four units) fell from providing around ten percent of all new residential units in the early 1980s to a low of just under three percent in 2013.  Even as multifamily construction has rebounded since 2009, increasing its share of all units from 21 to 34 percent from 2009 to 2013, these smaller multifamily units have actually continued to decline as a proportion of the total (the chart shows the number of units, not the number of structures):


Triple deckers in Bridgeport, CT.
The permit data only begin to capture what is, I suspect, a much longer-term decline in this housing typology. Anyone familiar even in passing with the larger cities of the Northeast will immediately recognize the heavy predominance of the type in their older neighborhoods, as represented by the wood-framed triple-decker, or three-decker, house.  Whether built up to a flat roof, as in the typical image of the Boston triple-decker, or with the third story sheltered under a pitched roof, these are large and bulky structures that generally provide three spacious units with windows on all sides.  Despite the popular narrative of urban-dwellers fleeing cramped apartments for more spacious suburban homes, these units rivaled or exceeded in size the modest Cape-style single-family homes built in the 1940s and 1950s, were conveniently set on a single floor like the ranch houses that later became popular, and offered gracious architectural features such as bay windows and front porches that were often lacking in the new single-family homes. It would not be until the 1960s that the average new single-family home would significantly exceed the size of the ordinary triple-decker apartment.

The vertical axis shows the number of  two  and three-family
structures sold over the past three years within the metro area
.
Census data provides housing statistics both by year built and by housing type, but unfortunately does not combine these statistics, making it impossible to determine what proportion of the small multifamily stock was built at what time. A workaround can be had, however, by using year-built information from housing listed on the MLS, which should provide a neutral sampling of the overall housing stock. Performing this exercise for the Bridgeport-Stamford-Norwalk area, an area with housing from all eras of American history and continuing high demand, reveals an exponential increase in the type from the 1860s to the 1900s, then a slower increase to an all-time peak in the 1920s.  Small multifamily construction collapsed during the Great Depression, along with most other housing construction, but unlike single-family construction did not rebound, even though the Bridgeport area experienced a manufacturing boom in the 1940s and early 1950s that attracted many factory workers.  Instead, it continued a gradual descent into irrelevance by the 1980s and 1990s.

The appearance of these structures therefore coincided both with the industrialization of American cities and a wave of immigration from rural America and from foreign countries, with the particular architectural style of multifamily housing in New England perhaps influenced or inspired by the multiplexes common in French-Canadian towns and cities (a building type which Urban Kchoze's Simon Vallee has recently explored).  These buildings had particular appeal to new immigrants, who could with sufficient savings purchase such a building and rent the upper two floors out to other immigrant families (often, members of their own extended family) to defray the cost of housing or perhaps even earn some additional income.

Why these dwellings ceased being built after the 1920s, never to return in any great numbers, is a difficult question, but fortunately it is not one that I need to guess at.  MIT graduate student Jacob Wegmann authored a 115-page thesis entitled What Happened to the Three Decker, supervised by none other than Sam Bass Warner, which explores that very question and offers a series of possible explanations which are equally applicable to other forms of small multifamily structures:
  • Above all, exclusionary zoning, particularly in the 1970s and later, that restricted small multifamily housing from being built in those places where it would have been most desirable.
  • Concentration of the real estate industry in the mid-20th century, resulting in the production of large-scale tract subdivisions that were able to exclude multifamily housing altogether.
  • Federal involvement in mortgage finance starting in the 1930s and an emphasis on homeownership paid for by way of extended mortgage terms rather than over a shorter period with the aid of rental payments from tenants.
  • Other regulatory barriers, including parking requirements, disability mandates from the ADA and state laws and enhanced fire safety requirements that have increased the construction cost for small, non single-family structures.
  • A negative image of small multifamily dwellings that had always simmered among the native middle-class and which intensified during the 1920s and later, and which contributed to attempts to exclude these dwellings from newer areas of cities.
The last point, although it may seem less important, does indicate to me a genuine underlying problem with the three decker or stacked duplex form.  As an article on Worcester's three-deckers puts it, "to look at a three-decker means ... appreciating the attempts of three-deckers to echo freestanding single-family dwellings even in the midst of an undeniably urban setting and the effort to create an illusion of space for residents."  

Bridgeport, CT rent map showing lowest rents in duplex/
triple decker belt between downtown and outlying
single-family neighborhoods.  From Trulia.
That is, the small multifamily house was apologetically urban, and offered as its apology an attempt to mimic the outward form of the cottage or farmhouse style of housing prevalent in New England prior to the 1870s.  This reticence to adopt an unambiguously urban form left such structures appearing to be second-best, a characteristic that was not shared by rowhouse neighborhoods or those composed of larger apartment buildings.  The attempt to leave small gaps between buildings, rather than using shared walls, only served to emphasize the scarcity of space and lack of light and air as compared to larger lot single-family homes.  The virtues of having natural light on all four sides of a dwelling, however, were very much real and have been appreciated for decades by the residents of these apartments.

The limited appeal of these structures has had the upside of keeping them as relatively affordable housing options down the present day even in otherwise expensive cities.  Neighborhoods composed of them are not immune to gentrification, but their form and physical location -- typically in the inner-ring areas once served by streetcar lines -- combines to keep their rents among the lowest in the metro area.  

Although the building type has not come back into vogue, the notion of using a second residential unit on one's own property to help with mortgage payments has, through the New Urbanist revival of the so-called "granny flat" (a concept which goes by countless names, but never "duplex").  The strategy of appealing to homeowners' financial interests rather than to the need for more low-cost rental apartments is politically astute and has probably helped the idea gain traction.  In the meantime, in areas where demand is high, many single-family houses continue to undergo illegal conversion to multifamily use, indicating how the America of 2014, by banning the construction of small multifamily buildings and the division of homes into multiple units, once a commonplace process, is in some areas and in some respects doing an inferior job of housing the poor and recent immigrants than was the country of a century earlier. 

Sunday, July 27, 2014

Where Zoning Went Wrong

In previous posts on zoning, I’ve been pretty hard on the Supreme Court’s Euclid v. Ambler decision, which upheld the use of single-use, and specifically single family-only, zones.  In doing so, the nation’s highest court gave the formal stamp of approval to exclusionary zoning, holding among other things that cities were justified in excluding so-called “apartment houses” from residential zones.

The fact that this dispute even reached the Supreme Court in the first place, however, indicates underlying policy choices that occurred somewhat earlier. Professor Sonia Hirt, who has done extensive research in the greatly underexplored comparative zoning realm, has shown how in Germany, a limited number of zoning categories are established at the federal level, with specific implementation left to local governments.  Although localities can choose where to place these zones, they cannot create zones of their own.  Simon Vallee (at Urban Kchoze) has described a very similar regulatory regime in Japan, where the national government has established a list of certain permissible zones that cities may use.  Hirt mentions similar but even more permissive zoning arrangements in other countries such as Serbia, Greece and Bulgaria. 

Notably, whether by coincidence or design, it appears that in none of these cases have state or national governments established single-family detached-only residential zones. In general, these countries establish only floor-area limitations, thereby allowing both single-family and multifamily housing in all residential areas, and also permit small offices and neighborhood commercial even in the most restrictive zones. Importantly, lot size and setback requirements appear to be modest or minimal.

In contrast to the experience of most other countries, the United States, right from the start, delegated zoning
Munich zoning map ca. 1900. From Harvard Library.
powers from states to localities in spite of the fact that early 20th century American planners greatly admired the German zoning system.  The best-known instrument of this delegation, although it was not the first, was the Standard State Zoning Enabling Act, a document first devised in the early 1920s by Herbert Hoover’s Commerce Department.

The Act was a curious document: although it spent many pages devoted to the legal proceduralism of planning commissions, it offered little guidance, and contained no requirements, as to how localities should actually zone. This intriguing and highly consequential omission was not due to lack of interest or expertise.  Edward Murray Bassett, a principal author of New York's 1916 Zoning Resolution and of much of the Enabling Act, authored a handbook on zoning (entitled “Zoning,” what else) in which he laid out its purposes and proper role. Bassett’s work, one of many on the topic from that time period by such men as Harland Bartholomew and Herbert Swan, establishes several major themes to distinguish zoning in the United States which were reflected in the enabling act and which have characterized American zoning practice ever since:
  • Approval of the exclusion of commercial activity from residential zones. Bassett seems to have assumed, without explaining further, that excluding all commercial uses from residential areas was a desirable and legitimate end of zoning. Furthermore, he casually elided any distinctions between noxious and harmless uses: "[In] a residence district a home owner may try to carry on a sweat shop or a restaurant or a junk yard. How shall he be prevented? ... The ordinance should make such act unlawful and make provision for ousting the unlawful use." (p. 327).
  • Failure to disapprove of the exclusion of multifamily from residential zones. Although Bassett struck a cautionary note toward single-family zones, this appears to have been primarily because he feared (mistakenly, it turned out) that courts would strike down such zones as lacking justification (p. 323-324). This, in turn, might have cast doubt on the fledgling enterprise of zoning. Elsewhere, he advocated for such zones as a means creating preserves for wealthy urban homeowners (p. 323). Bassett also suggested the use of maximum lot coverage ratios as an alternative means of discouraging apartment houses, notwithstanding that such coverage ratios would also have the effect of discouraging single-family homes on very small lots.
  • Extreme deference to localities. Bassett recommended that enabling acts transfer power to regulate the height, bulk and use of buildings to cities, apparently without any restriction on how these powers might be deployed in various zones. The states were to retain little or no power in the zoning area under his proposed arrangement, nor were they to provide any guidance except for the very vague suggestions within the Enabling Act.  There was no reason presented for this policy choice, and transportation policy was in fact moving in the opposite direction at the same time, with states and the federal government playing larger roles in planning and building highway routes.
  • Insistence on a "comprehensive" plan.  Although European zoning is often conducted on a block-by-block basis according to Prof. Hirt, and frequently leaves large central areas exempt from most restrictions, Bassett and other American zoning advocates insisted that courts would not accept such piecemeal or partial zoning, and that cities should therefore zone every inch of ground under their jurisdiction.  Allowing different zones within small and otherwise similar areas was also assumed to be unconstitutional "spot zoning," and was not advised.  Impliedly, these recommendations would intensify the use-segregated character and monotony of American zoning.  Nonetheless, once the initial plan was in place, selective rezonings (almost always downzonings) of politically influential neighborhoods were carried out and continue to be carried out to this day.
  • Irreconcilable conflict between planning and zoning. Bassett acknowledged that "[e]very vital growing city must change and the zoning plan must be capable of change," but quickly clarified that "a high degree of permanency or stiffness must be insisted upon." In other words, although zoning was adopted in the name of looking "mainly to the future," in Bassett's words, in practice, it would be highly resistant to alteration. To achieve this, Bassett included a proposal to limit the power of the city council to alter the zoning plan once it had been established by, in essence, subjecting every proposed zoning change to a referendum requiring 80% support of affected owners (see p. 330). What's more, Bassett's logic against zoning changes used only examples of upzoning or increasing permitted uses (see p. 330).  Downzoning was not critiqued.
  • Heavy reliance on legal process as a substitute for sound policymaking. Bassett, an attorney, was apparently aware that such permissive zoning powers might result in extremely restrictive regulations: "The letter of the ordinance and maps may be the extreme of hardship," he noted (p. 330). Rather than address this potential problem by advocating limits on zoning's restrictiveness at the start, Bassett suggested a Board of Adjustment with the power to grant variances. The obvious potential for abuse, graft and corruption in such an arrangement was noted by Bassett's contemporary, Lawrence Veiller, but the substance of Bassett's recommendations was included in the Enabling Act. Bassett dismissed these concerns out of hand in his book by noting that "it is the business of the mayor or appointing power to see that the board is made up of impartial and experienced men." (p. 331).
  • Rejection of aesthetic concerns. The City Beautiful movement of the late 19th and early 20th century, although it shared certain policy goals with the early zoning advocates, embraced a traditionally European emphasis on the outward appearance of the city. Architecture was considered an integral part of city planning, and planning literature frequently included lavish illustrations setting forth a compelling aesthetic vision for the city (what might be called a form-based vision).  In Bassett's view, however, aesthetics could not even supply a rational basis for zoning regulations: "If [regulations] are employed ... for aesthetics or some sentimental object, courts will not support them," he wrote. In short, despite his professed admiration for European planning methods, Bassett was waving the white flag before a shot had been fired in the legal battle.  Bassett was wrong again about how the courts would respond, but with most codes having been adopted under the erroneous assumption that such concerns were illegitimate, it would take until the mid-1990s, with the rise of the New Urbanism and the development of form-based codes, that architecture, aesthetics and form were given a more conspicuous role in zoning documents.
  • Concern with protecting the wealth of well-to-do homeowners.  Although Bassett stated that zoning "endeavors to protect investments" as a general matter, the investments he cites as examples tend to be those of very wealthy individuals seeking to erect expensive houses ("A man who built a $40,000 home ... was considered highly speculative because in a few years he might have an apartment house on one side and a factory on the other" (p. 316); "[A] man might put up a fine residence ... and find that the council had changed it to business and he was likely to have a butcher store on one side and a grocery on the other" (p. 330).  This was largely the extent of Bassett's social concern, such as it was, in his book. The interests of poor and middle-class residents, whether owners or tenants, went unmentioned by Bassett (in fairness, Andrew Wright Crawford, writing in 1920, claimed that zoning was "for the protection of the poor man," although did not address the exclusion of apartments).
  • Lack of comparative focus. Although Bassett claimed to have been inspired to become involved in zoning matters after a visit to an urban design conference in Dusseldorf, his treatise dismisses European planning models early on as inapplicable to American constitutional government, thereby depriving readers of the chance to learn from non-American planning precedents. Bassett even goes so far as to claim that zoning New York took as long as it did because "there were almost no precedents to help," which was only true if one completely disregarded decades of European zoning practice.
Zoning didn't remain an entirely localized concern by any means: the federal government would, only a decade or so later, become indirectly involved though FHA lending practices, and several states have since adopted regional plans, though not one of the 50, so far as I know, sets out zoning categories that cities must use. Federal fair housing laws would also become entwined with local zoning practice in the 1960s and later, but only incidentally. These original purposes, however, have endured with relatively little change and virtually no challenge over the following ninety-plus years.  

I've quoted legal criticism of some of these doctrines in the past, but there was scholarly critique at the time, as well, from progressive authors, some of it quite strident, but most of it now forgotten. For instance, the German-born Bruno Lasker, writing in 1920:
"Whence, to ask a very simple question, do so many of the zoning commissions derive their sanction for dividing the physical make-up of the city into use districts that distinguish between the residential needs of different classes? ... Why, in this country of democracy, is a city government, representative of all classes of the community, taking it upon itself to to legislate a majority of citizens -- those who cannot afford to occupy a detached house of their own  out of the best located parts of the city area, practically always the parts with the best aspect, best parks and streets, best supplied with municipal services and best cared for in every way? Why does it deliberately segregate the foreign-born who have not yet become sufficiently prosperous to buy or rent a home under building regulations which preclude the possibility of inexpensive development and construction?"
Social justice inquiries like these evidently didn't keep a legal-minded pragmatist like Bassett or his allies up at night. What's more difficult to tell is whether, had the federal government not taken such an active role in promoting a vision of local government-based planning and zoning, a more European zoning model might have emerged in some states.

Related posts: