Category Archives: Street Network Evolution

the evolution of urban street patterns over time

A central neighborhood square where all major pedestrian paths converge

A mature Fused Grid plan in Manhattan, NY

By Fanis Grammenos

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Cities print their history in stone. To read it takes deciphering just as if it were written on a very large Rosetta tablet. The first impression that jumps out when looking around is their constant growth and evolution: they grow ever-bigger, ever busier, richer and diverse; as if an unfathomable people-magnet was at work.  And they change: buildings morph into shapes unseen before; entire city blocks are reshaped; streets are straightened, widened or, conversely, twisted, blocked and narrowed. In some cases, where people used to walk freely becomes prohibited terrain and, in others, where cars were the main occupants disappear out of sight. What explains all this constant commotion, perpetual rearrangements?

 

 The Stuyvesant layout transforms the old grid into a Fused Grid

The Stuyvesant layout transforms the old grid into a Fused Grid

For example, the stone-text does not explain why certain places have only straight streets and square blocks, as Manhattan does, and others have hardly any, like the center of Boston or Istanbul. Nor does it reveal why perfectly straight streets in the older parts of certain cities morph into curvaceous shapes in their newer extensions at the edge.

A simple answer says that they evolve to adapt to new pressures and a new culture. But this abstract talk explains little, e.g.: What are the pressures and which are the matching adaptations? Such are the questions that naturally spring up on encountering a large, enduring development in New York – Stuyvesant Town.

When walking downtown along 14th street you realize that a dramatic transformation happened in the area north of 14th street and east of 1st Avenue: The familiar repetition of streets and blocks suddenly stops; the 200-year old grid of numbered streets and avenues that dominates Manhattan dissolves. Instead, the streets that enter at its boundary turn around and exit on the same road. What prompted its planners to give up the grid? Why the transformation?

 

A tranquil street that connects parts of the neighborhood
A tranquil street that connects parts of the neighborhood

A walk through the neighbourhood and a scoop of history provide some clues. The fist overpowering impression is that you are now in the country, that you left the city with its noise, smell, dust, cars, and frenetic pace behind; coolness, freshness and quiet prevail. You are in a protected “garden” where nature dominates your senses and restores your mood.  These effects can be traced to the eve of the 20th century when planners dreamed of marrying the country and the city in a “perfect union” and launched a global “garden city” movement. Stuyvesant Town could well be a realization of that dream with an important twist: The pioneers went to the country to build the good city, Stuyvesant brings the country into the city; city density  combined with the restfulness and tranquility of a garden.

A central neighborhood square where all major pedestrian paths converge
A central neighborhood square with a fountain where all major pedestrian paths converge

Another synapse fires when you realize the scarcity of ordinary streets and abundance of paths. Instead of cars racing by, only people stroll by: young and old, couples and kids; each moving freely at their own pace. In the few minutes that it takes to cross the neighbourhood, you walk mostly under a tree canopy or near a fountain or beside a grass-bed and flowering plants. Though built decades before the term “sustainability” was coined, this neighbourhood has all the qualifying ingredients: more walking than driving; proximity to public transit; less asphalt, high proportion of absorbing surface; large tree canopy and abundant shrubbery that reduce the heat island effect and increase rain absorption; high residential density; and primary convenience amenities nearby. It also encourages a healthy, active lifestyle with its tennis and basketball courts, swimming pool and daily recreational running, walking and sunbathing. Its buildings do not shade one another, offer plentiful sky-view and good exposure to sunlight. Parking is out of sight below grade, thereby restoring the ground to nature and people. This “must-do” list for any “green” place checks out fully in this 60-plus year old neighbourhood. It could well be that its planners were in tune with the emerging green priorities ahead of their time. Now it can lay claim to an honorary title – Sustainable. And one more too – Sociable; nothing encourages casual social contacts more than the unhurried, peaceful walking environment of its common grounds.

Its plan layout that renders it sustainable, sociable and delightful, however, remained nameless, undecipherable; a pictogram or ideogram that had no match in the planning vocabulary, at least not until recently when two new terms were coined – Fused Grid and Filtered Permeability: fusing but not always mixing active travel with motorized; where one stops the other takes over; methodically in pattern-like configurations, similar to Stuyvesant’s plan. And “filtering out” motorized travel and “filter through” active modes such as walking, biking and rollerblading by design as in Stuyvesant Town; a coveted, profitable development and a great model to follow: A practical, workable version of the “garden city” idea.

 

 

 

Cover-CitiesandForms

Book review: Cities and Forms

Cities and Forms by Serge Salat in collaboration with Francoise Labbe and Caroline Nowacki, published by Hermann Editeurs des Sciences et des Arts

Book review by: Fanis Grammenos and Woytek Kujawski

A compelling new book from  architect and planner Serge Salat sets out on a daunting mission to determining the ideal form for the sustainable cities of the future. Fanis Grammenos and Woytek Kujawski assess whether “Cities and Forms” hits its intended mark, and describe why this tome could soon become a central piece of the urban planning canon.

Cover-CitiesandForms

“No theory can define a city form sufficiently complex to meet the current challenges of urbanization.”

These words come from a rare synthesis of history, theory and design about cities  by Serge Salat, a researcher, planner, architect and artist. This work could soon belong to the list of classic reference works on urban planning for many reasons:

First, for its bold philosophical bend. Few earlier and even fewer current works attempt to explain the structure of observable city form using a theoretical model. Salat’s book sets out on a formidable challenge by looking at cities beyond their surface to reveal their formative rules.

Leaf Circulation System Structure

  Caption: The leaf and its fractal network of veins permeates Salat’s book as a metaphor for city structure.

Second, for its immense scope. It analyses, critically evaluates, and sums up centuries of urban thinking, traces the history and evolution of several cities around the globe, and correlates their physical form to the ideas and forces that shaped them. Its eight parts and thirty chapters span the gamut from the highly theoretical to the exceedingly practical, completing a circle not usually attempted in other studies.

Third, for its introduction of innovative city-form metrics. Eulogies have been written about certain cities (and condemnations  of others) before, but rarely are we given to understand what lies behind their attraction, what elements sustain their magnetism. The section on Assessing Urban Forms goes beyond simply describing the “the good city form”, to measuring it, by summing up previous discussions on city morphology and distilling them into several  ready-to-use formulas.

Fourth, for its many exquisite illustrations that, not only enhance the understanding of the text, but often are the text, fully explanatory of an idea in themselves.

The book sets out to accomplish an ambitious goal: to find the means of addressing what the author presents as fundamental issues, or flaws, of cities in their current state. At the intersection of the natural and man-made laws governing urban forms, and the city as-built, the author hopes to identify formal “anomalies” to which current city issues can be attributed. The list of problematic conditions includes connectivity, scale, gaps, ugliness, inhumanity, energy use, and, on the theoretical level the impact of “modernism” personified by Le Corbusier. The task of uniting all aspects under one theory is daunting, if not impossible, and as the author recognizes: “No theory can define a city form sufficiently complex to meet the current challenges of urbanization.”

Undaunted, he takes on this pioneering, massive challenge. As with all truly path-breaking works, the book sets up a direction, and opens up new vistas for exploration and, at the same time, raises new questions. As such, it is a work in progress, and further exploration in the following areas would strengthen this new approach and magnify its potential influence.

Connectivity

The author sees lack of connectivity between cities and people as a major current issue. The author describes the superior connectivity of historical cities where social and physical connectivity was synonymous. If connectivity is understood as primarily social, the means for enabling it must be considered in tandem with its prevalence. Modern technologies allow connectivity to escape its original physical space bounds, suggesting that the metrics for connectivity could be extended to include “social connectivity” provided by media such as television, telephone, and the Internet.

Were the metrics to be extended, one might discover that contemporary cities are far more connected than their predecessors, both in space and time,when connectivity is seen as social and its outcome as “social capital”.  Revisiting “connectivity” is one intellectual challenge the new paradigm poses that could be addressed by a future piece; a sequel, perhaps.

City as a Fractal  Structure

A second issue, that the book tries to produce answers to, relates to the overall conception of a city as an artifact that exhibits coherence and, through it, harmony and meaning.

The book reiterates the presence of fractal order in organisms and posits that such order is a fundamental prerequisite for a well functioning city. The leaf metaphor is juxtaposed with a tree and both are compared conceptually to a city’s street network. Some cities, or parts of them, are leaf like, while others are dendrite.  The implication is that the former are “good” because they display universal organic principles and the latter could be dysfunctional. This presumption of quality runs into difficulties when the case of Haussmann’s intervention in Paris is presented as  a contribution to the improvement of the city. Haussmann worked on a medieval city that had grown organically over centuries, a process that in fractal theory should naturally lead to a fully functional form at all levels; an “organic” city. Yet it was Haussmann’s surgery that rendered its street network “organic” in its distribution of sizes and lengths; a logical puzzle. However, the analysis of fractal order in selected cities is confined to their old parts and does not extend to the new areas such as suburban Paris, Prague, Rio de Janeiro or Barcelona. Were these areas to be included, the result might show a thick borderline between “conventional” fractal and chaotic. Conceivably, they may also be fractal, but with distinctly different dimensions. Such analysis may answer the question, for example, whether the Parisian suburbs are in fact an organic fractal growth added to the thousand-year old city or not. If not, then they must find a new theoretical classification that integrates them into the body of the city of which they are parts.

Paris Metro Subway System by the year 1970 Connecting daily millions of people within a 5 km radius, these boulevards, unimaginable by Haussmann, are not counted in the “connectivity” of   city form. Note their organic, piecemeal growth, far from a rational engineering diagram.

Modernism

While reading the book it is hard to miss the frequent polemical tone which contrasts sharply with the general scientific, academic (and sometimes poetic) language. Its target is Modernism and the assault is relentless. As a didactic tool to prevent a repetition of the movement’s alleged sterility is welcome.  However, Modernism has been discredited and derided extensively and no one is currently practicing or defending “Modernism” as according to Jencks’s (1973). It’s hard to escape the impression of a personal anti-modernism bend; however, the reason for such passionate attack is not readily obvious.

Conclusion

 This volume is a unique contribution to the planning literature for its new perspective, its depth and the weaving of many strands of science, art, history and sociology into a complete tapestry.  The author has attempted a synthesis of diverse disciplines to create a book on city planning that belongs both in the classroom and on the practitioner’s desk.

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Fanis Grammenos is a principal of Urban Pattern Associates and was a Senior Researcher at Canada Mortgage and Housing Corporation for over 20 years. He focused on housing affordability, building adaptability, municipal regulations, sustainable development and, recently, on street network patterns that lead to the Fused Grid model. Prior to that he was a housing developer. He holds a degree in Architecture from the U of Waterloo.

Woytek Kujawski  is a Senior Researcher at Canada Mortgage and Housing Corporation, an Architect Certified as LEED AP and a member of International Initiative for a Sustainable Built Environment. His areas of expertise cover Green Building construction and Sustainable development.

The new building form creates exclusive pedestrian streets and private outdoor patios

Building Hybrids

By Fanis Grammenos

Our house types lexicon includes standard, familiar species such as single detached, semidetached, townhouses, walk-ups and apartments. Each of these carries a set of images, an identity, and with it, deeply rooted feelings.  “House,” for example, spontaneously evokes privacy, independence, tranquility, a garden, and, frequently, a happy family and wealth.

These stereotypical associations often misjudge specific samples of homes and places; a “house” can range from a simple abode to an elaborate estate.  The same is true for other types. Some past “townhouses”, for example, were homes to prosperous citizens and were so exquisite that are now coveted masterpieces of domestic design. Prominent public figures raised families in spacious and well-appointed “apartments” at the city center close to their offices. Today, select downtown condominiums provide space, amenities and finishes that only few houses can boast about.

A new type of Townhouse provides privacy and comfort
A new type of Townhouse provides privacy and comfort

Yet there is some basis to the typical reaction and rushed judgement by established residents when they object to certain “types” in their community. Commonly, each type of accommodation has been segmented by district, price range, amenities and, inevitably, by income or lifestyle groups. Walk-ups, for example, usually have no common open space or, when they do, it is a leftover, uninviting, unattended area that detracts, rather than bolsters, overall desirability. Similarly, townhouses are often too narrow for a driveway and a proper entrance, leaving no space to grow a welcoming tree. These drawbacks sustain a stained image but are not inevitable; they can be overcome with ingenuity and innovation.

Innovation

Breaking the mould and demolishing stereotypes burns creative builders’ candles. Innovators search for adaptations, combinations and fusions. The typical narrow-front townhouse mould, for example, has been broken in at least two ways: by moving the car to the back in a lane-way or by making the lot wider and shallower; both increase house appeal and make economic sense. The next adaptation of the townhouse type includes a fusion and a transformation.  It blends one-storey units with two or three-story ones in groups of six to eight and sheds the boring, unattractive,  endless repetition of identical units in a military row. Each group is crafted to give the appearance of a unique, large Manor House. This fusion attracts a wider range of individuals from different strata, income and life stages, from the young family to the retired couple. One more successfully tested hybrid on the repertoire.

The lines of hybrids keep expanding from the well-used residential tower on top of a commercial ground floor to shopping malls with libraries or universities and to multi-story parking structures with at-grade commercial uses. All these blends increase project viability, street vitality and customer appeal.

But a major fusion has been happening recently in housing types both in function and in appearance. An extension of the reconfigured townhouse is its fusion with the conventional, and usually plain, three-and-a-half storey walk-up. Walk-ups occupy the top rung of layout and construction efficiency and, with it, the claim to affordability. With these two advantages entrenched, the new hybrid blends the merits of the townhouse with this form and opens up new opportunities for neighbourhood site layout.

The new building form creates exclusive pedestrian streets and private outdoor patios

The fusion gives every unit a front door, as in a townhouse, and to the units at grade a front patio for favourite outdoor activities and the occasional neighborly talk. The addition of balconies on the upper floors placed judiciously, gives the assembly the look of a grand villa with a portico.  Finally and crucially the new form acquires urban civility by putting the cars under the building. You might call it a triple fusion except that this new building allows for a fourth: fusing roads with exclusive pedestrian streets. Gone is the asphalt with sidewalk cuts for access to each townhouse garage. In its place, there is a pedestrian bricked path, fully landscaped, free of risk, noise and car fumes; a refreshing experience. Gone also are the miniscule, almost unusable townhouse backyards; they are reborn as a sizable neighborhood park landscaped to accommodate play, rest, contemplation and casual socializing: a breath of community.

The new hybrids in building and neighborhood layout are showing the way to safe, enjoyable and satisfactory living; a living that also has a lighter carbon footprint: the most frequent and pleasant way to move around in such neighbourhoods will be on foot. Due to its modest density, conveniences will emerge a short walk away. And with parents and kids re-appearing in the exclusive pedestrian paths, the familiar image of a car-packed street will fade into memory.

Blending traditional building types and fusing pedestrian streets with common roads, opens the hybrid way to efficient and rewarding neighborhoods.

 

CatamaranPriests_traveling_across_kealakekua_bay_for_first_contact_rituals2

Navigation and Legibility

 

In an earlier article, Beloved and Abandoned, we presented the grid plan, using Portland’s layout, as a historic relic perhaps deserving of attention but clearly unfit for replication in contemporary settings. That, evidently, is not occurring in any case. Several commentators quickly pointed to the supreme legibility of the simple grid as a counterpoint; clearly an indispensible attribute, they said. But is it?

The value of legibility lies in its presumed link to navigation. It is assumed that good legibility makes navigation easier. But does it?  Is a simple, orthogonal geometry aligned with the cardinal directions a necessary condition for easy city navigation? Apparently not, as we shall see.

Though related, the two concepts, navigation and legibility, are quite distinct. One is about an act and the other about a mental construct. “Navigation” and “way-finding” appear interchangeably in architectural and planning literature and they both mean reaching a destination with ease. “Legibility” which originates from text reading, is harder to grasp, but it does relate to a map in the mind, be it a letter, a picture or a configuration of streets. Legibility expresses the ability to project an image and discern its match with what one sees. Navigation as an act could be compared to dancing – a sequence of rhythm-coded steps that is partly or entirely preset and that becomes intuitive.

The first notion to consider in deciphering this puzzle is that navigation, or finding one’s way to a destination, not only predates geometry by millennia, but it is also a basic skill of most sentient, even “non-intelligent,” life. Examples abound from bees to birds to fish and turtles and many more. Closer to home, emotional, and sometimes incredulous, recounting of pets returning from a distant foster home, point to that instinctive ability.

In humans, a few striking examples, first from the non-urban world, show the distinctiveness of the two concepts and the independence of navigation from geometry.

Inuit will trek for many kilometers beyond the base horizon in pursuit of game, often in poor visibility, in what seems an undifferentiated, unremarkable, featureless landscape and, surprisingly to us urbanites, find their way to a destination and back home with astonishing efficiency.  Legibility, understood as a geometric order or map, is entirely irrelevant in this landscape.

 

 CatamaranPriests_traveling_across_kealakekua_bay_for_first_contact_rituals2

Figure 1. The feat of seafaring for thousands of kilometers in the Pacific Ocean without a single navigation aid still astonishes cultural anthropologists and navy captains (image from Wikipedia)

An even more astonishing example comes from Polynesia. For many centuries before they were “discovered” in 1595, the Marquesas inhabitants had ploughed the vast Pacific Ocean in stone-age-tool-crafted open catamarans to trade with and settle in other distant pacific islands. The crew of ten included a captain and a “wayfinder”, two very distinct roles (the wayfinder does not sleep!). Not a single navigational aid existed on board. These seafaring traders and settlers were able to regularly reach distant ports well beyond the visible horizon, often thousands of kilometers away, with accuracy and efficiency that surpassed by far the skills of fully equipped European sailors.  A great captain, Magellan, for example, sailing west from Cape Horn, missed the Marquesas and other pacific archipelagos to land, months later, with a malnourished and decimated crew, on Philippines.  The Marquesas wayfinder “knew” his directions with infallible precision. Nothing could be less “legible” and more disorienting than a vast, featureless ocean during weeks of sailing.  Evidently in this case, legibility, as a geometric construct, has little to do with navigation.

 Figure 2: A typical medieval city street network within a perimeter wall, now a peripheral arterial. Visitors get easily lost in the maze, but not its residents.
Figure 2: A typical medieval city street network within a perimeter wall, now a peripheral arterial. Visitors get easily lost in the maze, but not its residents.

 Figure 2: A typical medieval city street network within a perimeter wall, now a peripheral arterial. Visitors get easily lost in the maze, but not its residents.

From the urban world, examples also show that navigation does not depend on legibility.  Most visitors describe Arab cities such as Fez, and Marrakech or Medieval cites such as Vienna and Martina Franca (Fig.2) or Asian cities such as old Tokyo and Mumbai, as mazes, impossible to navigate even with a map in hand. In each case, the street pattern lacks clear geometry, has no uniformity or repetition, is rarely rectilinear and seldom abides with cardinal directions. Yet for many centuries, the residents of these cities thought nothing of navigating through their streets. Even more surprising, these same labyrinthine streets had no names and house numbers, yet posed no difficulty to reaching destinations.  Intensifying the surprise, are the cases of planned Roman cities with a highly legible orthogonal grid that were transformed into maze-like patterns by their subsequent occupants as if legibility was undesirable.

 

Figure 3. Old Vienna’s street network is typical of many medieval cities: irregular, idiosyncratic, varied bock sizes and shapes with multiple orientations,  maze-like. (green indicates pedestrian-only  streets) Giving verbal instructions to a destination could be an insurmountable challenge; following them, an impossibility.

If navigation was not an issue in these early pre-urban, non-urban and urban conditions, then the introduction of a simple geometric arrangement of straight streets and repetitive blocks would seem unnecessary for that purpose. In fact, Aristotle, long after Hippodamus drew the famous grid plan of Miletus, argued against his configuration and in favour of the old, “organic”, labyrinthine pattern on the grounds of defence, as did Alberti 1,500 years later. Camillo Sitte made the same case on aesthetic grounds, entirely unconcerned about legibility, having lived in Vienna, (figure 3) a medieval city, and grown to admire many other similar cities, with irregular street patterns.

These examples show clearly that humans on foot, on horses, carts and in boats have been able to find their way to a destination in natural, non-urban and in urban environments unaided by geometry and printed maps. The one presumed outstanding feature of the simple grid, legibility, proves to be unnecessary for navigation and simply an after the fact attribution by post-Guttenberg humans looking at maps.

Fanis Grammenos is a principal of Urban Pattern Associates and was a Senior Researcher at Canada Mortgage and Housing Corporation for over 20 years. He focused on housing affordability, building adaptability, municipal regulations, sustainable development and, recently, on street network patterns. Prior to that he was a housing developer. He holds a degree in Architecture from the U of Waterloo.

 

 

 

A connected cul-de-sac gives kids a chance to play

The Hopscotch Proof

 

Two widely reported, and most likely related, trends have planners and parents concerned: the increasing number of overweight children and the growing number of hours kids spend looking at a screen, be it a television or laptop.  And between the two of them, they take most of the free time kids have after school.  Add to these trends the tendency for kids to be driven or bussed to school and you get what has been coined as “nature deficit”; kids growing up not connecting with their natural surroundings.  Over the long run, the outcome could be physically unfit and socially maladjusted young adults. The warning statistics are all around us.

Is there a way out of this unhealthy cycle? Can neighbourhoods be laid out so as to avoid these unwelcome results?

 

Evidence from research pronounces an unequivocal ‘yes’. Many pieces shape the puzzle that forms the complete answer:  One has to do with what draws people out of their houses and prompts them to socialize with neighbours.  Since 1980, several studies have shown that the great inhibitor to socializing on a street is traffic: the heavier the traffic the less the socializing. Invariably, the less the socializing the fewer the friends adults and kids can make and the lower the attraction to get out of the house becomes. The latest, 2008 study, showed that people on a cul-de-sac had four times as many friends and two times the number of acquaintances than residents on through streets with heavy traffic. It seems intuitive and proof confirms it.

A second piece paints a picture of what streets young kids play most on: you may have guessed it already; it is the cul-de-sac, research shows. Kids on a cul-de-sac spent 50% more time playing than kids on other streets.  Importantly, kids’ playing on the street is not the end of the story; the benefits continue. Other studies have shown that play and exercise in the early years build an affinity that can last a lifetime.  Other work has also shown that pals tend to do what other pals do more frequently than as single individuals; the spirit of the beehive at work.

A third piece of the picture is about magnets in the surroundings that will pull kids out of their homes and send them walking to school, the corner store and other destinations.  A study found that of all the elements would attract kids of all ages the strongest common force was the presence of open space.

Another piece of the puzzle, though not the last, is how parents feel about letting kids play on the street or walk to school or ride their bicycle. Whether they read the sad statistics or not, they feel uneasy about letting them go.  Justified or not, their fear limits the range of activities that kids can engage and builds unhealthy habits.

The features

With these four pieces of knowledge from the field, we can now sketch out the essential elements of a child-friendly neighbourhood and, beyond that, a child-friendly district. Here is the set:

One, there should be no through streets in an area the size of about ten city blocks. Such a feature will give kids plenty of room to move around in a low-traffic, low-speed environment. Parents will socialize and kids will play. Parents’ insecurity will fade. The easiest way to create that feature is by using connected cul-de-sacs and crescents.

A connected cul-de-sac provides grounds for children's play
A connected cul-de-sac provides grounds for children’s play

Two, every such neighbourhood area should have at least one open space, whatever its size. That would grant a safe haven for play; a magnet.  Its land value will be fully recovered through higher values for the homes around it. Cul-de-sacs and open spaces command higher home values, real estate research shows.

Three, allow for bike and foot paths separated from the road that lead to school or other places with as few road crossings as possible. That will appease parents about letting their kids walk or ride to school and widen their horizons.

Can all this be achieved with a layout? Yes, by selectively fusing well known elements of available community plans.  A number of examples of this fusion exist and plenty of advice is accessible. And these techniques are not just for planning new neighbourhoods; existing places too can be transformed to create child-friendly environments. Initiatives in many cities have changed neighbourhoods with positive results.

Having done all this creative work, how can you tell you succeeded? Is the neighbourhood truly child-friendly? One sure sign is the chalk hopscotch marks left on the pavement! They signal that the kids took possession of a street and were having fun.  And every new family that moves later into the neighbourhood will be heir to its physical and social benefits.

For referenced studies and design solutions try fusedgrid.ca or e-mail the author

 Fanis Grammenos

 

 

 

Photo Caption: Pedestrian Streets, featuring houses and offices, dominate this new district. All rainwater is collected for local use.

Low Carbon Communities

Many speak of the need to measure the sustainability of development projects in order to avoid confusion and prevent the unchecked “greenwashing”.  Sustainability measurements involve aspects such as energy use by housing units, offices, and cars; watershed protection and sensitive land preservation, to list just a few. But while some aspects are relatively easy to measure (e.g. electricity use), others are quite difficult and some almost impossible because they get tangled up with influences that cannot be separated easily; health, for example.

 A community with affluent residents will generally have more cars and, invariably, more cars mean more driving, particularly when there are young children in the household. Some critics would quickly jump to the conclusion that these residents will be less healthy due to the amount of driving and downgrade the community on that score. Research has shown that this may be a hasty conclusion*. The affect of driving on health, if present, may be overwhelmed by the influence of income and education (two of several factors), both of which correlate with better health.  Until there is a sure way of separating the influence of each factor, we can defer the health-via-driving judgement. However, we need to remember that one community element that has been clearly linked to a positive influence on health is the presence of nearby open space – no project could neglect that feature, if it seeks the brand of “healthy”.

Photo Caption: Pedestrian Streets, featuring houses and offices, dominate this new district. All rainwater is collected for local use.

Measuring watershed protection (another item on the green list) is easier, given that rainwater outflow can be calculated using the subdivision plans, weather data and soil conditions. Assigning scores to a project gets complicated, however, when the size of the site enters the picture. Larger sites, usually suburban, have more opportunities to dissipate rainwater than smaller “Centertown” redevelopment ones. Small water retention numbers may indicate serious site constraints rather than lack of effort to green the project; the verdict could not be clear-cut.

We have less difficulty measuring carbon emissions whether they come from house energy use or from driving.  For building energy use, there is plenty of software to do an estimate with a proviso.

Car usage and emissions in seven European projects
Car usage and emissions in seven European projects

 We know that, once the occupants move in, the predictions can be off the mark by as much as 50% or more; the real numbers emerge after occupancy. But the estimate is still a useful benchmark.  For the amount of driving residents do, prediction is close to impossible; we can measure it only after built-out and full occupancy. Claims about a low car-use community any earlier are simply hopeful aspirations.

Yet, unreliable as they may be, trustworthy projections about driving can be made based on precedents for which there are precise numbers; enter the seven European projects described in a recent report*. These are impressive numbers. The simple chart lists the amount of driving in each, the amount in their surrounding district and, for shock value, the driving in some “good” and “bad” Canadian subdivisions.

It shows that these stellar projects made substantial gains in reducing car emissions. Driving dropped by 30% to 60% of the surrounding district’s share of trips. By contrast, and as an indication of the potential for betterment, even the best performers among Canadian suburbs show multiple times the amount of driving of these projects and also their districts. Even the differences among them are telling: they seem relatively unimportant by comparison to the drop that the seven European projects achieve; a 15% reduction in driving, at most, among Canadian subdivisions as compared to a 25% drop of the lowest achiever among the seven European projects. This cross-continent comparison may be somewhat unfair because of the many differences in context but it serves to demonstrate the enormous potential for gains in our communities.

How did the European developers do it? Many tricks come into play but three top the list: a) layouts that promote walking; b) Priority on bicycle networks and c) support for high-quality transit.

Then comes the important element of overall density: Density and quality transit are the chicken and egg question of low driving communities – they cannot be separated; they must come together from day one. This is the one prescription you cannot do without, if the project is to reduce driving.

In Canada, including these and other recommended elements in the plan will not guarantee less driving but, if we take cues from these examples, it may usher the prospective community in the direction of a greener place.

 Fanis Grammenos

Urban Pattern Associates

 * Two articles on driving and health can be found at:

www.planetizen.com/node/53728 and www.planetizen.com/51851.

** The full report on the 7 projects is available in PDF format at:

www.itdp.org/documents/092611_ITDP_NED_Desktop_Print.pdf

*** A research report from CMHC:

“Comparing Canadian New Urbanist and Conventional Suburban Neighbour­hoods” (66954)

 

 

 

 

 

A mini-park connects three looped streets - a Fused Grid technique

Innovation in Regulation

 

Regulation has a Jekyll-and-Hyde, split personality – attentive and autocratic. On one hand it cares and protects, and on the other, it restricts and confines. Abolish it, and watch people begrudge living in a place where everyone makes their own rules. Conversely, few of us wish to live by somebody else’s. Where do you draw the line? There lies the dilemma that many municipalities face when they enact regulations; between ensuring public protection and not limiting the public’s choices; a tricky juggling act.

This dilemma in planning regulations stems from the clash between tradition and innovation, between experience and exploration, and between practices that have worked and techniques that could work. Tradition asserts that something has worked but exploration counters that a new way could deliver better results. Can a balance be achieved between the assurance of past practices and the promise of new?

It can, and here is how Red Deer in Alberta achieved this balance.

A segment of a subdvision plan shows the pedestrian connectors
A segment of a subdvision plan shows the pedestrian connectors

The issue was, and it will puzzle other municipal heads for a while yet, how to give people on foot an advantage in getting to nearby destinations without restricting their choice of a place to live. Resident location preferences have been documented in market surveys which show consistently a strong desire for living on cul-de-sac and loop types of streets. These types are a fairly recent addition to the street vocabulary, but have quickly gained enormous popularity. Distressingly, they come with a disadvantage – they limit the options for walking to nearby places.  Before the car, that limit would have been an unthinkable restriction on movement; no one would want to walk longer than absolutely necessary for a physically exerting errand. With the car around, this disadvantage seems unimportant. But, it still means limiting personal choice. The obvious solution: Return the 19th century pedestrian era plan where no cul-de-sacs or loops could be found. Too simple: such a solution would limit another personal choice – the preferred place to live; hence the need for innovation.

A newcomer to the realm of neighbourhood planning, the fused grid, showed a solution to this riddle. Many developers quickly grasped the idea and embraced the fused grid model for its many advantages and, importantly, for allowing choices for mobility AND for a place to live. A few ventured forward and applied it, but many others, mindful of existing municipal policies, have shied away from it, fearing approval delays. Delays mean unplanned and unwelcome costs; not an option in a competitive market. The result: new ideas go on the shelf, for a while, at least.

A mini-park connects three looped streets – a Fused Grid technique

Smart regulation

Regulating a street pattern, even if it appears ideal, could stifle innovation; it would stop evolution and adaptation to new circumstances. By contrast, regulating the public benefit and choice that patterns should provide, could become a stimulant to innovation. There may be many untried ways of achieving these benefits. A balanced, smart regulation would let them all come forward and become part of the planning vocabulary.

And that where the innovation lies in Red Deer’s approach to regulation found in its Community Planning Guidelines and Standards document. Rather than prescribing “preferred plans” by means of sketches, the guidelines describe “preferred results” or preferred performance. In simple terms, it says that whatever pattern you chose for your plans, mind the pedestrians and do not disadvantage them: use paths or parks or both to shorten their trips.

 Quickly, variety site-specific solutions started to emerge from developers and planners. For example, the City of Saskatoon designed collaboratively and approved a community plan that applies this very idea (drawing 2). The plan shows, in one case, two cul-de-sacs and a loop  converging on a small park; homebuyers get both mobility and street type choice and a bonus – the delight of nearby nature, tranquility and a valuable property. In another approved development three loops converge to a park: choice, sociability, safety and delight are also present in this layout. (drawing 1)

The Guidelines point the way to a pragmatic approach to regulation: one that protects residents’ options and does not restrict design freedom. As more municipalities follow the Red Deer’s leadership, developers will turn a new page and produce walkable, delightful neighbourhoods. The Guidelines have changed the game rules.  And, inevitably, new layout ideas will emerge and propagate.

The Red Deer guidelines can be downloaded here: http://www.reddeer.ca/City+Government/City+Services+and+Departments/City+Planning/Community+Development+Plans/default.htm

Many neighbourhood layouts that meet the intent of walkability  can be found here: http://www.flickr.com/photos/22392855@N08/sets/72157626176042534/

 

Animals provided most transportation power until the 1900s

The Transformative Power of Energy

 

A shocking piece of news recently brought home the formidable potency of energy: over 300 million people in India were left without electricity, all of Canada ten times; chaos ensued. Factories, offices, hospitals, and traffic came to an abrupt and apocalyptic standstill.  The engines of the economy, cities, were silenced.  Losing power to such epic proportions has never been the case in the past and for good reasons.

Up to a century ago, in 1850, men and animals supplied 94% of the world’s energy and 5% came from fossil fuels; a ratio that lasted for millennia; no power interruptions in that scenario. But by 1950, a mere century later, the numbers were reversed: 93% of energy came from fossil fuels and 6% from people and animals. And much of the fossil fuel burned to supply the electricity grid which provides power to 75% of the world’s houses, offices, factories etc. Astonishing, unimaginable things happened in that century and the years that followed and, reportedly, more are in store. About 90% of all inventions since the Promethean fire emerged in these last 150 years.  Why so?

What lies behind this enormous creativity? Ultimately, energy. As more hands are displaced by machines, more brains can switch to nurturing ideas. But a second and equally powerful lever to this creative surge is cities: apparently, the bigger they get the more innovation they generate: doubling a city’s size increases its creativity by 15%. Several cities have doubled a number of times in the 20th century producing a compounding effect.  Cities become beehives of creativity  because they connect people. As different brains interact, more synapses fire, each leading to yet another potential innovation or enterprise. A new tool in the hands of others finds uses unforeseen by its inventor; and the spiral grows exponentially. 

Animals provided most transportation power until the 1900s

Connectivity

The storyline of connectivity between people traces the path of transportation which shapes the city and determines its size. When human and animal power provided all transport, making a connection meant a trip on foot or hoof and a face to face encounter. News spread at walking speed of 5 km/hr; a slow and often arduous process. In that era most cities reached a population around 30,000 people and a size of about 20 minute walk across. News emanated and propagated from the barber shop, the communal water spring, the pub and later, when coffee become common, the coffee shop.  The circle of interaction was small and the ideas local; inventions were also mostly local and stayed local for generations. When the coal-fired steam engine came on board and followed by the electric motor, cities changed dramatically.

Steam-engine trains and electric trams boosted city size at least ten times and now news and ideas  could be had from places weeks away on foot, in just a day; a double benefit for creativity.  Still, relatives, friends and businesses could only talk to one another by letter; long trips were unaffordable for most.  But the beehive was now much larger, more people interacting and the speed of inventions started to accelerate to the point where a US Patents Office director would declare around 1900s “all that could have been invented has been invented”. The news transmission tower was still at a street corner in the pub or coffee shop.  All of that changed when electrical wires became the highway of communication with the invention of the telegraph and then the telephone, radio and television. 

Overnight the creative “city” was as big as the reach of the telephone line or of the radio signal, which had no practical limits.  Important news about discoveries, opportunities and people came out of speakers or screens.  The barber shop, pub and coffee shop talk was demoted to trivial chit-chat, gossip; little gain to be had from it.  The transmission hub moved to a secluded room someplace no one knew; it didn’t matter.  Electricity made connectivity possible without travel by using wires or airwaves; without travel and at the speed of light!

Not only communication was freed of travel, it was soon freed of filtering, control and reach. With the internet and the cell phone everyone is a hub and a receiver of ideas at the same time.  A video story by anybody can reach a million people or more; at least twenty times the foot and hoof city population.  While you teach a trick to someone on line you can learn another from someone else. Anyone’s ideas can “infect” countless unfamiliar people. City creativity was given another rocket booster.

From walking down to the corner to get news and share ideas to being virtually at every corner of the globe without leaving your living room, connectivity has traveled a long way in a hundred years, thanks to the power of electricity. Power is key to a better future.

A reclaimed street becomes a stage

Renovating Cities – one block at a time

Just like buildings, cities need a good makeover once in a while. And the reasons are pretty much the same for both. Time has battered their infrastructure, which has either reached or surpassed its life expectancy. Also, during this life-cycle new systems have emerged that do the job better and, sometimes, at lower cost;   

These two drivers, wear and tear and the new, efficient systems would be sufficient reasons to start the renewal phase. But there is an even more compelling reason – cultural change – and, with it, our own expectations and aspirations. Cultural change is not simply about shifting music styles and dress codes. It is predominantly about the way we do practically everything in the city. The way we shop, communicate, become informed, do business, make friends, meet mates, entertain and educate ourselves, and take care of children.  In the last sixty years cultural change that covers these activities has been momentous and it demands that the city accommodate it.

Take the typical downtown bock and its surrounding four streets, for example. It used to have buildings arrayed in sequence, soldier like, separating the private domain from the public realm; private life behind the perimeter “wall”, public life on the street side. That’s the model of the past – when streets were the spaces where people strolled, socialized, sold and bought wares and struck business deals. The same block is now a walled island surrounded by a moat of cars; the public realm has mutated to a domain, where streaming, belching by cars, buses and trucks  overwhelm the senses and induce stress; an unpleasant experience that calls for  renewal. This unwelcomed condition results mostly from our enjoyment of convenience; door to door commuting or errand running in the comfort, speed, flexibility and privacy of a car; a favourite cultural change.

The city block can and has responded to this new urban cultural condition by reclaiming one of the surrounding streets, or creating “streets” inside the block or both. In some cases, an inside or outside “square” is also part of the response, completing the gamut of the public realm functions that the contemporary street can no longer sustain. In other instances, the traditional hard corner of the building recedes to become a street-side court, an added bonus for pedestrians.

This set of responses sync with our new-found quest for quiet and concentration, hopefully in the presence of greenery, where conversation can extend beyond a hurried yelling of codified phrases and OKs.  Tranquility and green are in gross undersupply in most city centres.

Examples of these approaches to renewing the block and street are increasing. Typically, residential, office or hotel towers jut up from a common base of lower buildings that include longitudinal or transverse “streets” or both. Usually, the structures occupy most of the block but no longer opaque to through movement; people can traverse it in one or both directions, peacefully, safely at their own pace. This block permeability lessens the need for a four-side car access to it; three or even only two-side access would suffice; a fact that opens up the possibility for reclaiming at least one street for pedestrians, a double gain.

A reclaimed street becomes a stage
A reclaimed street becomes a stage

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Land economics demand maximization of the building footprint. An outdoor space within the bounds of site requires creative thinking and a City willing to make bold decisions for its citizens’ benefit. An uncommon example shows that an imaginative deal was necessary in order to create a most cherished outdoor space in the heart of a city. To turn part of the site to an open, green space, the developer was given two road lanes, one at each end of the block, for access and egress from the underground parking. Being on a hill slope, this 200’ by 125’ open space provided a natural setting for stepped, amphitheatric seating. Traffic suffered little from the change, access to parking was made non-disruptive and the citizens got an unprecedented gift. Imagine the attraction of a downtown where many of its blocks are treated in a similar way; a delight for the residents and an irresistible lure for visitors. The recipe is simple: make city blocks permeable to people and selected streets impermeable to cars.

Modern-day Paris owes much of its functionality and charm to a powerful bureaucrat – Baron Haussmann – who renovated the city in the 1860s by slicing avenues, grand boulevards, squares and parks through the old, rundown, labyrinthine city fabric; a task contemporary municipalities would not even dare contemplate.

In today’s cities renewal can happen in less ambitious and disruptive ways, one or two blocks and streets at a time. When driven by the new cultural realities, such renewal can gradually transform dull urban spaces into charming places.

Sixand12-footStreetsCompposite

Choosing a grid, or not

In an earlier article we discussed Portland’s grid flaws, prominent among which was inefficiency of land use.

We looked at Portland’s 200’ by 200’ block in the context of other layout options and, when we compared it on a number of criteria, it did not fare well. New data* on other American city grids, that emerged since, which are analysed here, sheds more light on this assessment and also open an opportunity for refined versions.

We argued earlier that if the merits of the specific Portland grid plan were self-evident to planers or developers, its use would have been expanded in the city beyond the original plating of 1846 and imitated by other cities, neither of which has been the case.

For this analysis, we used twenty city grids that range from a mere 150 by 150 feet, just over one half acre, to the ten acres of the largest American grid of Salt Lake City (660 by 660 feet). These gridiron layouts also span a range of street right-of-ways (ROW) from 30 feet to 120 feet.  The present analysis focuses exclusively on comparing land use efficiency among the twenty grids. It consequently raises the inevitable question as to which would be a suitable candidate for a contemporary “town”, “Planned Unit” or a suburban subdivision, if any at all.

Figure 1: Chart showing the influence of the right-of-way width on developable land.

We did two types of calculations: a) we measured the land use efficiency of each one in the set by calculating the ratio of buildable (or saleable) land to the total land that includes the right-of-ways (ROW) for streets, as platted and b) we did the same calculation by adopting a constant ROW for all in order to see the effect of the grid frequency (street frequency or street density).

Chart one finds Portland as the third least efficient of 20 urban grids with a buildable land use ratio of 59% and an implied 41% of land dedicated to ROWs. This finding confirms the earlier assessment. The trend lines in the chart reveal the inverse relationship of ROW width to the efficiency of land use, as might be expected. What emerges as more instructive however, is the amount of difference between a low performing grid (e.g. Houston) and a high one (e.g. Charlottesville). From the 57% of the former to the 75% of the latter there is an approximate 30% jump in land use efficiency. Such difference would impress any urban planner and would be decidedly a priority for a developer. Each for a different reason is keen in optimizing the yield of land put to urban use: sustainability for the former and economic viability for the latter. Interestingly, the Houston city block is 1.3 times larger than Charlottesville’s, yet less efficient; a counterintuitive fact that lead us to look at the influence of block size.

 

Figure 2: A chart showing the correlation of grid block size and land use efficiency

Chart two demonstrates the impact of block size after removing the variability among ROWs and adopting a uniform 60’ width for all cities. Portland now appears as the second least efficient grid in the set, confirming again earlier assessments.  The difference in efficiency between it (59%) and Denver’s (71%) is about 20%, not an insignificant gain in saleable land and reduction in infrastructure costs.  (The exceptional efficiency of Salt Lake City is only apparent as we shall see later.) Instructively, Charlottesville migrated from the most efficient in chart one to the third least efficient (below Houston) in chart two, due to the adjustment of its ROW. This chart reveals a strong correlation between block size and land use efficiency; the smaller the block the lower the efficiency of the grid. Looking at both charts simultaneously, the correlations among all three variables become clearer.

Based on this analysis, we can now consider an optimal, simple, open grid; or perhaps not. There may well be other considerations that would suggest abandoning the homogenous, repetitive grid altogether in favour of another type of layout. Endurance, for example: If replication is any indication of merit, the record does not bode well for the simple grids of the set (as can be seen in Google Earth images): Few of the examples in this set show a continuations beyond the original mile square plan; the majority begin to grow in size, change proportions and even geometry. And as for new towns or subdivisions using them as stencils, the current record is empty. In addition to low survival rate, there are also persistent old and new criticisms.

Key planning figures either through theoretical works or by virtue of built projects have denigrated the simple grid and, in some cases, even orthogonal and rectilinear layouts.

Olmstead in the 1800s abandoned orthogonal planning and introduced curvilinear streets that were to become the model for innumerable subdivisions. Camillo Sitte portrays the grid as unimaginative and unworthy of consideration for new towns. Raymond Unwin in his writings and works rejects the simple, open grid, succeeds in ushering the cul-de-sac through the British parliament and lays out plans free of the rigidity and repetitiveness of the simple grid. Serge Salat tells us that “Unwin joins Sitte in recommending a great variety of street widths, which would enhance the specific character of each street. In the design of districts, the interior streets should not be too wide.  Wide streets planted with trees should be reserved to the outer boulevards where they offer the threefold advantage of serving as promenades, ensuring traffic between districts and delimiting the districts”. In other words uniformity of street width diminishes character and inhibits delineation. In the same vein, Lewis Mumford writes a scathing critique of its use in town planning adding that “..The new gridiron plans were spectacular in their inefficiency and waste”. Clarence Stein creates a model that follows in the footsteps of Unwin dismissing the grid as entirely unsuitable for our times. Recent pioneering projects such as Village Homes, Davis ,CA; Seaside, FL; Kentlands,  Gaithersburg, Maryland;  and Laguna West, Sacramento, CA use layouts that abandon the simple gridiron pattern.

Figure 3. A sampling of 3 simple grids and their corresponding percentage of land used for ROWs.

From the very recent perspective of seeing cities as organisms that obey fractal laws (seen in the works of Alexander, Salingaros, Mehaffy, Mashall and Salat), more fundamental weaknesses of the uniform grid emerged. For example we read that: “Making a line straight, or regularizing a street, as 19th century urbanism has often done, eliminated intermediary scales and hence the possibility of geometric interaction and coupling of smaller scales. In other words it killed life. For thousands of years, historical cities avoided straight lines, creating multiply connected rich structures by way of slight discontinuities in relation to straight lines.”(Salat)

The same author infers that the intent that drove the creation of the simple grid may not have been entirely benevolent: “It is only when an absolute power absolutely controls the ownership and use of the ground that the city can conform to a perfectly geometric form, as was the case in the ancient Chinese capitals or the cities of colonial occupation in North and South America”

In the last 20 years, researchers confirmed the heightened risk of collisions that grid layouts engender and the negative role its unfiltered permeability plays in maintaining security and sociability in a neighbourhood.  Also, from a sustainability perspective, the grid plan has been found deficient because of its potential high ratio of paved surfaces; its land waste; its disruption of natural land features and its low operating traffic speeds.

In spite of this evidence against the simple grid and the complete absence of new applications of it, we may still wonder if a simple grid can be chosen on the basis of two known grounds: its legibility and the speed at which it can be surveyed. All simple grids in the set share these attributes irrespective of their size.

Figure 4: The turning radius of a team of four oxen pulling a four-wheel cart determined the width of the streets in Salt Lake City. (Image source: Wikipedia)

Knowing the relative impact of the variables we examined, the choice among grids becomes easier but, heeding the criticisms, also irrelevant. However, an opportunity opens up to manipulate them by selecting desirable elements from each; no need to copy uncritically. For example, the highly unusual, 120-foot ROW of Salt Lake City’s streets (based on the long-outdated need for a team of four oxen pulling a cart to turn around within the street) would be unjustifiably wasteful and unpleasant if used for residential streets, where traffic is low and buildings small. Similarly, its 660 by 660 (10 acre) block size (based on homesteading family units, mostly extinct now) cannot be subdivided efficiently for current two-income-earner family houses. These historic changes in socio-economic structures are in fact reflected on the ground; many of Salt Lake City’s original blocks have been divided in half by a mid-block road. Consequently, its exceptional theoretical efficiency on the chart evaporates in practice and renders the block as found unusable. Clearly, choices should be made with an eye to current socio-cultural conditions.

 Modifying the ROW width can definitely lead to substantial efficiencies, as we saw. Charlottesville shows the way with the narrowest streets in the set (30’ and 40’) and highest land use efficiency (chart 1). But we need not copy Charlottesville. We know many Greek, Roman, medieval and Arab streets to be much narrower, starting at 6 feet and averaging around 15 feet wide. All these streets functioned adequately for pedestrian movement and still do in surviving city centres that date back to original layouts. But, as with the block sizes, current trade, work and transportation modes bear little resemblance to those when these streets were conceived and used; direct copying may not work.

Figure 5: A 6-foot (left) and 12-foot wide streets (right), millennia old, worked well for the foot-and-hoof traffic of their time.

It is plausible that earlier street dimensions might find an application in contemporary networks: Salt Lake City’s 120 width, for example, as a divided boulevard with six lanes of traffic and a 30-foot linear park for pedestrian movement on either side while a 15’-wide Roman street, as a pedestrian-only, landscaped route connecting wider residential streets that are designed for car access. In this vein, efficiency can be matched with purpose.

Figure 6: Savannah’s composite, 13-acre cellular grid, at 55%, and a 40-acre, contemporary cellular grid at 74% land use efficiency. (Plans at same scale)

Breaking the convenient, but unnecessary, uniformity of the 18th and 19th Century American grids would be a first step in recovering the land efficiency mandated by current ecological and economic imperatives. Pointing in that direction, Savannah’s composite, cellular grid includes variable size streets and blocks for private, civic and religious functions. A second step would be to include block sizes that can accommodate comfortably prevalent building types and sizes unknown in the 1800s, again defying block uniformity. A third step would be to adapt its streets for the now universal motorized mobility, of cars, buses, trucks, trams and motorcycles, that is radically different from when oxen, equine and legs shared the transport of goods and people.

In summary, examining the simple grids in this set serves as an introduction to optimizing land use, people circulation and the movement of goods. The resulting challenge is to use these insights to develop patterns that accommodate contemporary urban land economics, transportation, environmental priorities and citizen aspirations as these patterns may have done in their time.

Fanis Grammenos, Director
Urban Pattern Associates

*Credit goes to Daniel Nairn (http://discoveringurbanism.blogspot.com/) for the list of American grids with dimensions.

This article was first published in Planetizen.com