Friday, December 9, 2011

Friday Read: Parking – In the Long Run

One of the things I most enjoy writing about on this blog are the nuts and bolts of built urbanism: square footage counts, ratios of building coverage to open spaces, measures of urban connectivity and so forth.  Thankfully, I've discovered that there's a community out there that enjoys reading and learning about these subjects too.  Although it's not glamorous work, often involving careful study of aerial maps, census figures and property records, it is an essential element in understanding the successes and failures of urban environments.  In comparison to some other trendier areas of urban study, it can get short shrift.

UConn's Chris McCahill enjoys researching many of the same things.  In a recent study which has been picked up at The Atlantic Cities and at Felix Salmon's blog, among other places (unfortunately not freely available on the web), McCahill and Professor Norman Garrick examined three New England cities New Haven, Hartford and Cambridge and attempted to track the change in downtown parking over a period of 50 years, using historic aerial photos as a guide.  The results of this meticulous study were contrasted with the change in population and employment in these same cities, with an eye toward testing the hypothesis that increased access to parking is correlated with commercial and residential real estate development.
Courtesy of Chris McCahill

The results are shown at right.  New Haven and Hartford, whose post-1950 urban renewal efforts were aggressive even by the standards of the day, lost both jobs and residents as parking increased.  Cambridge, on the other hand, which in 1981 lowered minimum parking requirements while imposing maximums, stemmed a population decline while substantially increasing the number of in-city jobs, all without making drastic interventions to the urban fabric.

A reasonable critique of the data might be to suggest that parking is only a consequence, rather than a driver, of urban prosperity.  As the industrial fortunes of New Haven and Hartford withered, built form may have given way to so-called "taxpayers," vacant lots held to reduce property tax burdens pending an upswing in the market for commercial real estate.

McCahill and Garrick's findings, however, suggest that increased parking in New Haven and Hartford was the result of conscious policy decisions. Mayor Biagio DiLieto in the early 1980s boasted that New Haven had more parking than any other Connecticut city, according to the study, affirming a commitment to “maintaining and improving parking facilities for workers, shoppers, and visitors in the downtown area.” Anyone who is familiar with Douglas Rae's City: Urbanism and Its End, can attest to how strongly the New Haven planners of the era (particularly during the mayorship of Richard Lee) believed the success of downtown to hinge on its accessibility to suburban motorists.  Not only surface parking but garage parking as well surged during this era.

A particularly surprising finding of the study is that despite their planners' focus on downtown as a setting for office buildings, rather than residences, New Haven and Hartford both suffered declines in employment from 1960 to 2000.  This occurred in spite of the fact that, in the mid-1950s, Hartford was still a largely mid-rise city built along a 300-year-old, semi-emergent street network, while the city of today is notable for a dramatic skyline of tall office buildings.  Again, the aerial view may hold a clue: a comparison of views from the 1950s and the 1990s provided by McCahill (see slides 6-9) shows that tall buildings at Hartford's core may have at best only compensated for the loss of hundreds of other low and mid-rise structures to renewal schemes.  Cambridge, on the other hand, which has a modest skyline and few tall buildings, has dramatically increased in-city employment during the past 30 years, even as its resident population grew.

Additionally, the study shows that per capita car ownership has increased faster in Cambridge than New Haven and Hartford, yet car use is less.  These figures are in large part due to much greater growth in incomes in Cambridge than in Hartford and New Haven in combination with an increased focus on non-automobile modes of transportation.  Has the focus on building spaces for working and living, rather than parking, and walking and biking, rather than driving, also resulted in an urban environment more appealing to middle-class and wealthy residents?

As the authors summarize their findings:
"This study reveals a need to reassess the impacts of the demand-driven approaches to parking provision that are conventional in most U.S. cities, including New Haven and Hartford. A more balanced approach to parking provision, like the approach taken in Cambridge, would address real parking demands in a way that acknowledges that excess parking contributes to increases in automobile use, which in turn exacerbate parking issues."
The damaging effects of minimum parking requirements have been widely reported, but this is one of the first studies to take a very long term look at their effects in the context of trends in other urban activities.


  1. Downtown Toronto requires 1 parking spot per 1175sf GFA +0.06 visitor spots/unit for large condos and 0.34 (min) to 0.76 (max) per 1000 sf for a typical office.

    While surface parking in the Toronto's core is disappearing fast, the new buildings replacing them usually have multiple underground parking levels. So the amount of land used exclusively for parking is decreasing very fast, but the amount of parking is likely increasing with population/employment.

    Do any American cities have bicycle parking requirements? For large new buildings in Toronto's core, it's 0.75 spaces unit (to a max of 200) and 1 per
    1250m2 for commercial.

  2. Saw plenty of empty parking spaces as I passed through New Haven today. :)

    This study was interesting. I wish it could be replicated more
    easily. Their methodology is very labor intensive. I was looking into using GIS data for something similar this past summer, but I didn't really get anywhere.

  3. Urgh, it's depressing to even read the title ("City: Urbanism and Its End")... did people really think that way?

  4. @Nicolas: I believe New York recently adopted bicycle parking standards, and some other cities have them as well (SF and Portland come to mind). I would not say they are common, though. A multi-million dollar renovation and rebuilding of my local commuter train station provided exactly zero bike parking spots, even though it would have been trivially easy to incorporate them.

    @Matthew: It's true that it is a labor-intensive method, and probably cannot be widely replicated, especially with much larger cities, without tremendous effort. Still, the points made are widely applicable. I believe the authors are continuing to develop new methods for examinining these issues as well.

    @Snogglethorpe: Despite the title, it's really a biography of New Haven. The "end" of urbanism in the book refers to the decline or disappearance in that city of the characteristics which, in sum, Rae understands to constitute "urbanism." Definitely a worthwhile read I thought.

  5. Some people mapped the surface parking lots of various cities here:

    The one thing about the way The Atlantic Cities measured parking is that it assumes most of the supply is surface parking. I don't know about New Haven or Cambridge, but for cities like New York, Chicago or Toronto, I think parking is mostly multistory structures or below other uses and not visible on satelite images.

  6. Thanks for that link, Anonymous -- those maps are great. As for the study, it states that it did not account for underground or on-street parking, although it does count above-ground parking structures.

  7. I know when I visit a city the thing that I really enjoy is looking at parking structures. That's a big draw.

    (sarcasm off)

    I'd say the problem here isn't just parking, it's planning. City governments decided on policies, and (surprise!) they turned out to be bad ideas. Cities should _respond_ to what the citizens do, not try to mold their choices.