On People, Parking, And Cities - Michael Manville and Donald Shoup

Searching for authoritative numbers on how much of urban space is devoted to cars, I found this gem by Manville and Shoup, People, Parking, And Cities. The authors debunk the numbers bandied about by many — two thirds of LA is devoted to car use, etc. — as being undocumented if you follow the trail of citations. They found that Meyer and Gómez-Ibáñez (1983) had proposed an inverse relation between the share of land in streets and the share of land in streets per person, based on 1960 data:

Automobile use does not result in an exceptional percentage of land being given to transportation purposes. Rather, the automobile seems to create exceptional demands for transportation land relative to the number of people in an urban area. Specifically, cities more dependent on the automobile tend to have more street acreage per person but a smaller percentage of total land in streets.

Basically, larger lots leads to low population density, but more importantly, as the car has become dominant in transportation the cities are designed for cars and not for people:

People, Parking, And Cities - Michael Manville and Donald Shoup

Given these results, how can we account for the perception that low-density areas give more of their land to streets? Certainly people tend to associate lower density with increased automobile use, and automobile use with streets. The first of these associa- tions, as we have seen, is more complicated than a simple one- way relationship, but the second may increasingly be true. The association between low density and auto-oriented land use, in other words, may lie less in the share of land given over to streets, and more in the share of streets given over to cars.

The modernist street designs identified by Southworth and Owens (1993) consume less total land area than the dense grids that preceded them, but broad boulevards and cul-de-sacs are also streets whose primary purpose—and perhaps sole purpose—is the swift and safe movement of automobiles. The desire in newer areas to accommodate the car has often led to the removal of other uses from roads and streets. Cul-de-sacs, which force more circuitous routes and have a notoriously limited utility for pedestrians, have been promoted. Intersections, which slow traffic or cause it to stop—but which make streets more amenable to walking—have been minimized. Those intersections that get built are made wider, allowing cars to turn with less deceleration but forcing pedestrians to traverse more road space (Southworth and Ben-Joseph 1996).

Where older intersections often have a curb radius of 3–4 ft, newer intersections flare out: It is not uncommon for zoning laws to call for 15 or 20 ft curb radii. The 9 ft travel lanes of older neighborhoods were replaced in newer developments by 11 and 12 ft lanes, and parking lanes are recommended to be wider still, so through traffic will not be unduly slowed when drivers pulled into or out of spaces. In practice, parking lanes rarely reach their recommended widths, but the standards illustrate a new concern with the street as a territory of the car, rather than as an arena for multiple modes and activities. In some places parking lanes have not been widened but instead prohibited entirely; Century City has banished all its parked cars to off-street garages, and reserves its broad streets for moving automobiles. The end effect is the same. Because curb parking can help make a street feel more human scaled (by encouraging movement on the sidewalks, and by providing a barrier between pedestrians and fast-moving traffic) its removal can amplify the sense that the street is a facility for cars alone.

Manville and Shoup reevaluated the study data that Meyer and Gómez-Ibáñez used, and reaffirmed the basic insights.

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They wrote:

Our results indicate that the relationship they identified between density, street space, and streets per capita is still valid. The coefficient of correlation between density and lane-miles per square mile was 0.87, while the coefficient of correlation between density and lane miles per 1,000 persons was −0.39. This latter coefficient is weaker than the relationship identified by Meyer and Gómez-Ibáñez, but still negative.

[…]

Columns 4 and 5 of Table 2 show each area’s daily vehicle miles traveled (VMT) per square mile, and VMT per capita. Like our figures for lane mileage, these numbers are derived from the TTI’s database. Given the relationship we have found between street space and density, it is reasonable to expect that VMT interacts with density in a similar manner. Previous research has shown that traffic volumes correlate highly with density: Ross and Dunning (1997), in a report to the Federal Highway Administration, found that traffic volumes rose at 80% of the rate of population change. It may be, however, that density and VMT share the same complicated relationship as density and street space.

Our calculations suggest this is so. For the 20 largest urbanized areas, the coefficient of correlation between population density and VMT per square mile is 0.90, while the coefficient between density and VMT per capita is −0.58. Los Angeles, the densest area, has the highest daily VMT per square mile (128,000), and by a significant margin. It sits in the middle of the pack in terms of VMT per capita. Using all 85 urban areas weakens the relationship only slightly: the coefficient of correlation between density and VMT per square mile falls to 0.86, and the relationship between density and VMT per capita becomes −0.47. Increases in population density reduce the VMT per person but increase the VMT per square mile. In low-density areas each person creates more VMT, but because there are fewer people per square mile the VMT per square mile falls. These findings accord well with the idea that sprawl can reduce congestion, but that it also makes for longer trips.

High levels of VMT per square mile suggest high levels of traffic congestion. For this reason it is not surprising that Los Angeles has such a large VMT per square mile, not only because it reinforces the popular perception that LA has the nation’s worst traffic, but because the region’s relative equality of density (which we discuss in the next section) deprives it of any truly low-density areas that would offer a respite from high congestion levels. We can follow this logic back further into our original seeming paradox: since congestion is properly thought of as competition for scarce road space, areas with high levels of congestion—which is to say dense areas—can be conceived of as lacking in road space, even though they have more of it than less dense areas.

Obviously the problem is not quite that simple. The optimal solution to competition for scarce road space is not more road space, but—as with competition for any scarce resource—prices. In the absence of road pricing, however, it is not uncommon for traffic engineers to state that a congested area has an undersupply of streets. Congestion worsens as population increases because the supply of streets is relatively static, and cannot keep pace with increases in density and VMT if everyone drives everywhere.

So, cities become designed around their streets, and the lower the population density (larger lots) the more time people spend driving in cars, which leads to greater congestion, like LA.

And the result is that cities like LA do in fact dedicate a higher proportion of space to cars.

This means that the rise of autonomous cars — even in places like LA, will lead to strong motivations to increase density, and to reuse space now dedicated to cars that are generally at rest: parking. LA has 24% of its central business district dedicated to parking, for example, leaving aside the underground and multilevel structures allocated to it.

The final table includes a wide variety of cities, including New York, and rationalize parking as a function of jobs in the city:

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New York has the amazingly low figure of 0.06 parking spaces per job in the downtown area, contrasted with LA’s 0.52: ten times more parking per person in LA than NYC, and LA is — to the authors’ knowledge — the highest percentage on earth.

The authors quote Lewis Mumford, who said

The right to access every building in the city by private motorcar, in an age when everyone owns such a vehicle, is actually the right to destroy the city.

And they close with a recommendation:

Perhaps the simplest and most productive reform of American zoning would be to declare that all existing off-street parking requirements are maximums rather than minimums. The examples of New York and San Francisco suggest that limits on off-street parking can foster many of density’s benefits, and urbanists who admire these cities might urge other places to adopt their approaches to parking. From a different perspective, however, more regulation may not be the best first step. The market can mediate the supply of parking in most urban areas, and despite the planner’s frequent desire to replace a floor with a ceiling, it may be better to simply deregulate parking—to force it on no one and let those who want it pay for it. A market-oriented approach to parking would eliminate cumbersome regulations, remove incentives to drive, and let city planners concentrate on matters that seriously demand their attention.

Or let some innovation like autonomous cars come along, and watch what happens when 70% or more of the cars go away.

What China Can Teach Europe - Daniel Bell via NYTimes.com

Daniel Bell tells us that we shouldn’t think of China as a conventional Westphalian nation-state. It might be more profitable to think of China as a network of competing — and cooperating — semi-autonomous cities. And these cities might be a harbinger of what other cities elsewhere need to become:

Daniel Bell via NYTimes.com

[…] when it comes to economics, China is more a thin political union composed of semiautonomous cities — some with as many inhabitants as a European country — than an all-powerful centralized government that uniformly imposes its will on the whole country.

And competition among these huge cities is an important reason for China’s economic dynamism. The similar look of China’s megacities masks a rivalry as fierce as that among European countries.

China’s urban economic boom began in the late 1970s as an experiment with market reforms in China’s coastal cities. Shenzhen, the first “special economic zone,” has grown from a small fishing village in 1979 into a booming metropolis of 10 million today. Many other cities, from Guangzhou to Tianjin, soon followed the path of market reforms.

Today, cities vie ruthlessly for competitive advantage using tax breaks and other incentives that draw foreign and domestic investors. Smaller cities specialize in particular products, while larger ones flaunt their educational capacity and cultural appeal. It has led to the most rapid urban “economic miracle” in history.

Bell contrasts two very different cities — Chongqing, the size of Austria and with 33 million citizens, 23 million of which are registered as farmers, and Chengdu, 14 million people in the heart of Sichuan — stating that Chengdu has worked on a bottom-up basis with very clear property rights and Chongqing the reverse, with sweeping land grabs displacing millions.

China, it seems, is trying out different models: an evolutionary experiment. Bell fails to mention that Chengdu was the last city held by Chiang Kai-shek and the Kuomintang before fleeing to Taiwan. The Kuomintang had brought a large number of business people to the area as the slowly were pushed out of other regions in China, so it makes sense that the city would be a locale to test a ‘gentle’ approach to urbanization’s dislocations.

Can you have a private city? The political implications of 'smart city' technology - Andrew Comer and Kerwin Datu via The Global Urbanist

Andrew Comer and Kerwin Datu via The Global Urbanist

According to UN-HABITAT’s State of the World’s Cities 2008-2009, 510 new ‘small’ cities, 132 new ‘intermediate’ cities and 52 new ‘big’ cities emerged between 1990 and 2000, with a combined population of 254 million.

IKEA Urbanism: A New Era In Urban Design? — The Pop-Up City

Will the new era of architecture be the era of IKEA urbanism? IKEA has proposed to build a complete neighborhood in East London. The Swedish furniture giant tries to implement its ideas and concepts in new fields of knowledge and urbanism. After its injection of each single family’s interior with cheap design furniture and the introduction of the IKEA standard house by daughter company BoKlok, it seems to be time for a complete IKEA neighborhood, reports the Huffington Post, LandProp — also part of the IKEA group — is planning to build a neighborhood of 1,200 houses, shops, cafés and a 350-room hotel.

Destroying Detroit (in Order to Save It) - Howie Khan via CQ

What can we learn from destroying Detroit?

Howie Khan via CQ

These days everyone in Detroit is talking like an urban planner. You can’t spend even a day driving through the city and not think in terms of land use, redevelopment, and urban identity. Entire neighborhoods, people gone and houses razed, are on their way to becoming prairies. The neo-Gothic shell of Cass Tech High School, fifteen emptied Art Deco floors of the Lee Plaza Hotel, the four remaining towers of the vacant Brewster Projects, hulked up identically off the interstate like broken soldiers locked in a standoff—they’re all coming down. The question becomes: What do we do with all this space?

The loudest answers thus far have come from artists and farmers who have moved to the city, those well-meaning ecocrats and conceptualists whose beliefs are rooted in the transformative power of installation art and organic kale. Buy a house for a hundred bucks, paint it outrageously (sherbet hues, polka dots) to make a statement, and repeat until a block becomes an MFA thesis, complete with its own sustainable food system. Which is all good in terms of psychic energy and creativity, but it doesn’t exactly qualify as a strategy for turning things around. Still, in Detroit, it’s worth looking for good ideas everywhere—starting with the most basic resource of the city’s 139 square miles. “Land itself has a value,” says Mayor Bing. “We’ve got to figure out how to maximize and get a return on the land.”

No other city of Detroit’s magnitude has the opportunity to begin again. Starting over now? It’s not exactly the kind of thing we do in America’s cities. We don’t go backward, we don’t clear-cut, we don’t shift toward empty to become full again. What happens next is really the great urban experiment of our time. How the city will be remade, and whether it really can be, will polarize. Planning wonks and architects, landscapers and CEOs, residents and visitors, even people who have never been to the city, all seem to be watching, harboring opinions and dream scenarios like kids playing with Legos.

At this point, only a few things are clear: The physical boundaries of the city will not shrink. Detroit will not become one big farm. Residents of certain neighborhoods will be incentivized to move. But precisely nothing can happen here unless the blight goes first. The city has $111 million in federal grant money to spend on cleaning things up. Thousands of Detroiters attended town-hall meetings in September and January with the mayor, his development executive, Karla Henderson, and his buildings and safety chief, Kimberly James, to discuss, with voices raised, what their city will become.

Master plans are being drawn up under a Rooseveltian rubric, the Detroit Works Project, which includes a $25 million light-rail system, an ambitious proposal for turning empty spaces into recreational greenways, and a focus on attracting sustainable industries. Completed plans are expected to be revealed in December. By then a dent should be made in Detroit’s inventory of at least 10,000 dangerous buildings that need to go down, and perhaps some of the 70,000 vacancies could be rehabilitated, revitalized, and sold. “There’s been a lot of administrations prior to this one that talked about demolitions,” says Bing. “Everybody set these high goals but never achieved them. I wanted to be realistic in my approach. My problem is that I’m not that patient.”

To the Shermans, to Lorenzo and Mike and Otis, the exact numbers don’t matter. Three thousand houses down now? Ten thousand houses by 2014? Seventy thousand empty homes? To them, that’s just political posturing. Building by building, it all needs to go. Whatever the count, they’re more than happy to help Bing meet his goals. After the mayor’s speech last year, Mike Farrow was determined to do his part to hit the 3,000-house target by December 31. “If they want me wrecking those last few houses at midnight on New Year’s Eve,” he told me last summer, “I’ll be out there dropping those motherfuckers like the ball.”

Can demolishing ten thousand empty buildings bring people and industry back to Detroit? Is it enough to clear? Don’t we need to build density, so servcies can be affordable, and the city can be a safe place?