Friday, April 29, 2011


A timely topic: Witold Rybczynski on density.     

At Citytank, Josh Mahar has authored an excellent post that explores the potential of street narrowing, a favorite subject of this blog.

Streetsblog explains how parking minimums make housing more difficult and expensive to build, but according to developers, they also provide a strong incentive to subdivide large lots into smaller parcels for which parking requirements are waived -- a design outcome which can be beneficial for the urban environment, where it is allowed.

Stephen Smith at Market Urbanism is rightfully skeptical of some of the claims made for green roofs.  I'd lean more toward Quinlan Terry's (and Léon Krier's) take on roofs (the "pitched slate and tile roof ... the architectural expression of every civilized age").   

Winner of the Driehaus Prize for classical architecture?  Who else but Robert A.M. Stern.  The somewhat lesser known Reed Prize is awarded to a person "who has supported the cultivation of the traditional city."

Wednesday, April 27, 2011

Narrow Streets in Advertising

Spotted on a Metro North train.  No photo of St. Peter's, the Colosseum or the Spanish Steps for Alitalia, just a shot of a really narrow streetIt must have tested well in focus groups?

Tuesday, April 26, 2011

More On Density

To follow up on the table I posted last week, I want to add a couple quick points in explanation of what my intent was in putting it together. 

The thought I had in mind was basically this one, drawn from an urban planning textbook:
“Depending on scale, the same density may look and feel quite different.  Perceptions on inappropriate density can trigger strong reactions from the public, with concerns about increased traffic congestion and concentrated poverty.  Good design employs scale as a way to make denser development feel humane and look appealing while capturing the benefits it brings to the human realm.”

If a slightly lower density could be delivered in a form that is far more acceptable as a housing option to the majority of people, still at an urban level of compactness, and cheaper to construct to boot, wouldn’t building in that form be a sensible choice even if the resulting city occupied somewhat more total land area?   The table shows that the low-rise forms are, in fact, not all that much less dense than taller ones, particularly in comparison to suburban forms, and even require less total street surface.

From this point of view, there could perhaps be a modest reconciliation among the anti-density NIMBYs and the pro-density urbanists, with resort to a time-tested form that was, in fact, the primary way cities were built from the time of Jericho and Ur all the way to the industrial revolution. 

The runaway popularity of the few partly-traditional American towns and neighborhoods is evidence that this is an approach that could succeed.  Unfortunately, it has never really been given a chance, not even by the New Urbanists, who, as I’ll get to in the next few days, have coded away any chance to build in a traditional form.

Thursday, April 21, 2011

Charting the Grid

A couple weeks ago I put up a post on Portland's grid, street widths and 19th century American city planning. With an apology in advance for all the statistics, I've put together a table to illustrate some of the numbers behind the grid form.

What the table shows in the first column is the amount of land, in acres, needed to provide equivalent amounts of building square footage for grids built with a variety of street widths and building heights, while always maintaining a 200x200 foot grid block (Portland's block dimensions) and 1:1 street width to height ratio (the assumption being that a benefit of wider rights-of-way is that buildings may rise taller without reducing the amount of natural light at street level).  For example, a city of two-story buildings on 20-foot streets would need to be 2.6 times as large as a city of ten-story buildings on 100-foot streets to contain the same amount of total built square footage.

The second column shows the amount of land, out of the total acres, that is occupied by the right-of-way in each scenario.  At the end of the chart I offer three examples of common American development forms for purposes of comparison.

This is similar to Floor Area Ratio, in a way, but I thought it was more helpful as a way to visualize intensity of land use over larger areas.  Some of the results to me were fairly surprising.  I'll post a few more thoughts of my own on this later, but I'd be interested to hear some reactions. 

(A few notes: the South Philadelphia neighborhood is essentially an area of 2, 3 and 4-story buildings set on 30-foot streets.  Sylvan Park is a typical gridded suburb of the early 20th century with wide streets and alleys behind each row of houses, inflating the amount devoted to roadway.  The Reserve is a randomly chosen example of a cul-de-sac neighborhood of houses approximately twice as large as those in Philadelphia or the modest bungalows of Sylvan Park, but I did not adjust on a per-unit basis.)

Monday, April 18, 2011

Monday Morning Urban Links

A few to start off the day:

Andrés Duany defends the New Urbanism against the critiques of the "Avant Garde Establishment," Landscape Urbanists, and others.

An editorial piece in yesterday's New York Times attempts to make the case that New York's grid is an environmentally-sensitive, "green" plan, citing in support the factually incorrect statement that the 1811 Commissioners' Plan "conserve[d] 843 prime acres as a Central Park."  Oops.

More from the department of "thinking small:" writing about Bucharest, an author considers the role of the human scale in architecture and planning in making cities worthy of being loved.

Canadian city proposes requiring suburban developers to pay higher fees to better reflect the costs of supplying city services to outlying developments.

Withdrawal of state funding threatens long-planned Cincinnati streetcar.

Thursday, April 14, 2011

Are Narrow Streets a Realistic Objective?

In response to a previous post about American city grids, commenter Josh Mahar made the following point, which I'd like to take a moment to address:

"However, wide blocks or not, it is what we have. It would be great if our streets were a bit smaller but they aren't and there is realistically no way to start shrinking block size now.

To add a bit of reality here, perhaps you can look into examples of innovative ways of creating more pedestrian scaled streets and spaces. One example would be the promotion of alleys as commercial streets. ... There are also possibilities of reinventing wide streets as front yards for gardening, bike boulevards, or more spacious outdoor seating.

The United States simple isn't Europe and our cities will never look like theirs. While its great to compare and contrast the differences it would be helpful to also look to a hopeful future as well."
This is an important point to ponder, because it moves this conversation about narrow streets out of the realm of the ideal and into that of the achievable.  If we can't realistically narrow streets or shrink block sizes in American cities, is this whole debate just academic?  And if so, aren't we really wasting time with this discussion, when we could be brainstorming more pragmatic ways of reclaiming our streets and public spaces for pedestrian life?

I have a couple quick thoughts in response.

First, I agree there's a lot that can be done, short of physically narrowing rights-of-way, to improve the pedestrian experience.  Over at the Strong Towns blog, a resource ("Tactical Urbanism") has just been posted which covers many small scale, low-cost ways to improve the quality of urban life for people on foot, or to at least get people thinking about these types of issues.  This stuff is great and represents, I think, the sort of thing Jane Jacobs had in mind when she referred to "tactics ... suitable to a strategy of attrition of automobiles by cities." (Death and Life, p. 474).  It's a battle for hearts and minds as much as for territory.

I would, however, question the position that street narrowings or block partitions are only pipe dreams.  Since the early 20th century American cities have carried out in unthinking fashion thousands of street widenings, many of which involved the use of the condemnation power and which resulted in the destruction of large numbers of urban buildings.  The idea of narrowing a roadway would have been incomprehensible to a traffic engineer of 1960; most likely the thought simply wouldn't have crossed his mind. 

With a mindset as pro-pedestrian as the earlier planner’s was reflexively pro-automobile, there’s no reason the opposite could not be achieved.  Just as one side of a street was previously slated for demolition for new freeways or arterial roads, one side could today be designated for expansion into the public right of way.  Or, in the case of extremely wide streets, development rights might be created in the center roadway itself.  A city could simultaneously reduce its infrastructure costs while adding taxable land to the property rolls.  These are just tentative ideas, open to debate and disagreement, but I do believe there is room for a lot of creative thinking here in terms of urban design and economically efficient allocation of urban space. 

The first step in the process, though, must be about identifying, diagnosing and understanding the problem in as wide an economic, historical and geographic context as possible.  For that I don’t think there’s a much better or more accessible starting point out there than Nathan Lewis’ writings on streets and urbanism, but with my few posts on narrow streets, grids etc. I’m trying to provoke the same sort of discussion.

Sunday, April 10, 2011

They Made a Desert and Called it a Park

A visit to a friend in Boston last week provided the perfect opportunity to take a walking tour of the downtown, the first time I'd been on foot in the area since the completion of the Big Dig a few years ago. 

The "Rose Kennedy Greenway," the much-touted ground-level replacement for the elevated Central Artery, has to my surprise been roundly criticized: although it's not a shock to hear James Kunstler chime in, in the Globe and elsewhere it's been called a "barrier between neighborhoods," "waste land," a "glorified median strip," a "design disaster" and "a placeless desert" (the last of these inspiring the shameless paraphrase of Tacitus in the post title).  The evident failings of open space on such prominent display seem to have spurred constructive thinking on urban planning, rather than just hand-wringing, among writers of all stripes. 

Crossing over from the North End toward City Hall, I snapped a photo of part of this park, a parcel which according to the Boston Zoning Code is designated as a "Recreation Open Space Subdistrict" (sounds fun!).  The plan also specifies a "major fountain to mask traffic noise" from the surrounding high-speed arterial roads and I-93 on-ramps, though no such fountain was either audible or visible.  Here's what $14.6 billion will buy after the digging's done:

Throughout the project, the mantra that the Central Artery had severed the city, and that its burial underground* somehow would "knit the city back together" seemed oblivious to the fact that it was not the Artery which had severed the city, really, but the demolition of over 1,000 buildings for the Artery's right of way which had done so.  Removing the Artery simply revealed that pre-existing wound to the heart of the city, a gap so wide and poorly-defined even Baron Haussman might have thought it could use a little narrowing.  The aerial shots below show what previously existed in the path of this right of way, the top photo dating from 1947, and the lower from the present day, with the Greenway clearly visible in the center (the total demolition of the West End and Scollay Square, at lower left, are also clearly apparent):
The story of how this all came to be stretches back three decades, and seems to relate to a crisis of the modern urban imagination.  As Globe architecture critic Robert Campbell put it:
"What should the Artery land be? Does it tell us something about ourselves as a society that, so far, no one has been able to come up with a vision that inspires consensus? ... Neither the people who govern us nor, probably, we the people ourselves have a clear idea what the public space of the 21st century should be. ..."
With no one able to agree on anything in particular, the environmentalists of the late 1980s stepped in to offer the compelling alternative of nothing, packaged under the name "open space," and obtained a requirement that 75% of the land above the buried highway be set aside for it.  The realization has only recently sunk in that even "nothing" must be paid for, as the conservancy tasked with maintaining the Greenway has now proposed taxing abutting property owners to raise funds, the largesse of Boston's citizens, already maintaining several very large parks in close proximity, apparently falling short.  Thus, land that, under private ownership, might have provided millions of dollars in tax revenue to the city, and hosted thousands of jobs and apartments, has become a money pit.

The missed opportunity is even more tragic given that one of the very few neighborhoods in the United States laid out in truly traditional fashion, the North End, with its narrow winding streets and attractive mid-rise architecture, sits right next to the Greenway.  The blank side walls of 19th century townhouses, their adjoining buildings demolished for the Artery in the 1950s, cry out to be extended southwards by new neighbors.  The elusive vision is right there, a reality, not a fantasy, yet somehow it escaped the attention of Boston's elected officials, planners, architects and the public itself.

On the day I visited, the North End was jammed with tourists snapping photos of the streets, students standing in long lines at pizza parlors, and many residents simply going about their daily business by foot.  The few on the Greenway were walking briskly either toward the North End or back the other way, and indeed, with such an extraordinary neighborhood so close by, the appeal of lying on a shade-less grass lawn between six lanes of roaring traffic loses any appeal it might have otherwise had.

Was there a sort of failure of the imagination here, an idea Nathan Lewis develops, that prevented and is preventing many Bostonians of the present day from really "seeing" the examples of good urbanism that are right in front of them, or thinking that they might be imitated?  I do not know, but the recent critiques, at least, do seem like a hopeful sign.

*Given the $15 billion price tag, I would have expected one of the alternative options to have been to simply remove the Central Artery without replacing it (see recent posts at the Infrastructurist here and here on freeway removal), yet I'm not able to find that this course of action, which probably would have cost less than $50 million, was ever considered at any point. 

Monday, April 4, 2011

A (Defense!) of the Grid: Portland and 19th Century American City Grids

This blog has not been kind to the grid in the past, but when it is criticized unfairly, it deserves a defense.  In a lengthy critique of Portland's street grid, planner Fanis Grammenos argues that the grid makes inefficient use of valuable urban land:
"The Portland grid uses 42% of land in right of ways for streets and has the highest length of road infrastructure of any alternatives. Simply put, nearly half of the land is used up in accessing the other half. ... Evidently, Portland’s founders either understood little about infrastructure costs or judged them irrelevant; a judgment that no planner, developer or municipality today would take at face value. When economic efficiency matters, Portland’s grid fails the grade."
Writing in response, Jarrett Walker of Human Transit perceptively notes that the amount of land devoted to streets is a function of the width of the streets rather than the grid plan itself.  Portland, like most other American cities founded in the 19th century, was laid out on a regular grid with streets of generally uniform width.  In Portland's case, this meant 200-square foot blocks separated on all sides by a 60 foot right-of way.  Although sixty feet may not even seem especially wide in comparison to some other cities, its constant repetition results in 41 percent of all downtown land devoted to streets and sidewalks (27,600 sq. ft./67,600 sq. ft.), virtually the same as Grammenos' figure above. 

If the founders of Portland could dodge the infrastructural expenses imposed by roadways of such width by simply leaving the streets filthy, unpaved and sometimes dangerous,* their successors in the early automobile age were not so fortunate.  In a 1919 article "City Planning For Portland," it is evident that the costs by that time have become too great to ignore:
"Whereas city engineers used to think that every street should be laid out as a through street, it is now found that we can only afford to provide the wider and heavier pavement on about every fifth or sixth street, called a main thoroughfare or major street.  ... Considered from this new point of view, some municipalities have begun to realize that a lot of money put into paving which is now unnecessary could have been used to splendid advantage in other ways. ... [I]t becomes evident that 200-foot blocks, particularly in outlying districts, are an extravagance ...."
Among other things, the planners of 1919 recommended much narrower streets and longer blocks for future residential areas, the identification and selection of a network of through streets, while also mentioning a "necessity for diagonal routes ... in many parts of the city."  A narrowing of certain existing rights-of-way, which would have gone a long way to addressing the planners' primary concerns, was not advised, although it apparently was within the realm of imagination.

Portland's case is not unique, but rather is representative of hundreds of American cities and towns of the 19th century.  The seemingly irrational decision to give all city streets an extravagant scale was replicated in plan after plan, even in rural hamlets.  Even if an emphasis on facilitating transportation ("wide enough for an ox-cart to make a U-turn") may have played a role, any such benefits were more than canceled out by the city's inability to pave the wide streets, leaving them a muddy quagmire in many cases well into the 20th century.  The vast amount of land set aside for streets also diminished urban density, leading to, on average, greater travel distances than in a city set along narrower ways.

It would be a mistake to fault the grid plan itself for this, however, as a grid may with only slightly more thought given to the initial plan, and less of an obsessive focus on perfect regularity, incorporate a range of street widths and block dimensions (Manhattan's grid being probably the best known example).  This will not cure it of all of its deficiencies, but it certainly will address Grammenos' criticism by helping the grid achieve a more favorable ratio of buildable to non-buildable land.

*From Wikipedia: ""[Portland in the mid-to-late 19th century] was a place where “stumps from fallen firs lay scattered dangerously about Front and First Streets … humans and animals, carts and wagons slogged through a sludge of mud and water … sidewalks often disappeared during spring floods.” ...  In 1889, The Oregonian called Portland "the most filthy city in the Northern States", due to the unsanitary sewers and gutters. The West Shore reported "The new sidewalks put down this year are a disgrace to a Russian village.""