Tag Archives: Urban

Bumpy rides a thing of the past, again.

          

Does a driver exist who actually likes speed bumps and humps?  If not, what are these road skin inflammations doing at mid-block or at intersections?

 It seems ironic that we paved bumpy, dirt roads to ease our trip and then, some half a century later, we purposely create bumps that turn it unpleasant. It’s also strange that at intersections, our three natural options for continuing on are often curtailed to two or just one; surprised and stuck with no choice! These changes sure look like embarrassing afterthoughts.

Bollards turn a 4-way junction into 3-way. Landscaping offers a relief.

We normally do renovations to systems that no longer meet requirements which stem from a new understanding of health, safety or efficiency concerns. We change steep stairs to prevent falls or upgrade an electrical service to power more home appliances.

But why remodel streets? After all they have functioned for hundreds of years.  True, but in the last hundred much has changed in them that slipped in unnoticed.

First, speed on the streets increased from a leisurely 5 km/hr to a hurried 30 and up to fifty; a six-fold increase at least. Then the size of their occupants increased from about a four square feet, a man’s footprint, to a driver’s of 200 square feet; a 50-fold increase. In addition, noise levels climbed from the human chatter of 50 decibels to the truck and motorcycle clatter of 75 decibels, more than a 100-fold increase in ear pressure.  And finally, a subtle existential angst pervades the streets; a wolf has found its way into a sheep’s pen; risk is lurking at every corner. These entirely new urban conditions call for remodelling; and remodelling we did and it will be going on for a while.

Take the cross intersection for example, a relic from the past. When people come to it, it’s a meeting place, but when cars reach it, it turns into a conflict zone. There are 32 ways that cars can collide in it. Unless the intersection is signed or signalized, every driver naturally believes in his right to act and move first.  Stats show that 4-way intersections have much higher frequency of collisions than the 3-way alternative.  The lesson learned, neighbourhoods started to remodel their 4-way junctions. One approach is to close one of the crossing streets at the intersection, promptly turning it into a 3-way.  Bollards, a clump of trees or planters make the closure an attractive feature. The second means is to install a traffic circle in the exact centre of the intersection. From a driver’s perspective, this addition has the effect of turning the crossing point into four virtual3-way junctions; direct forward movement is not an option. As with the closure, the circle can host shrubs, flowers, or a tree improving the street ambiance. Closures and traffic circles are just two of many ways of adapting the old network to the traffic it did not anticipate.

When remodelling or designing neighbourhoods for traffic, two goals are uppermost:  Safety and flow and in that order. 

What can traffic circles do for safety? Seattle’s traffic safety program, starting in the 90s, evaluated the impact of 119 traffic circles on accidents and injuries. It showed a whopping 90 percent reduction in both. And when counting all costs related to accidents, the installation proved convincingly cost effective. Five hundred more installations followed.

 Vancouver did its own renovation and remodelling of certain streets. It included street closures, traffic circles, diverters, curb extensions, and extra traffic signs. A study, that looked at the before and after frequencies of collisions and injuries in the entire district, found that there was a general reduction of accidents by 15 percent and, within neighbourhoods, of about 25 percent.

A small circle, provides a great safety bonus

But do traffic circles improve flow? Surprisingly, yes. Even though drivers slow down to negotiate the circle and other cars, the total network flow performance improves.

The lesson: neighbourhoods can do without the old four way intersections and improve safety to boot. Traffic circles are smarter bumps that cars drive by not over, recapturing the comfort of a smooth drive.

 These renovations bring welcome improvements to an antiquated network system.

New neighbourhoods can use the lessons from these upgrades and provide a safe and well functioning network from the start. The techniques are easy to apply:

a)      Avoid intersections entirely within a neighbourhood; unimaginable but possible.

b)      When junctions are necessary, use the 3-way version

c)      Use turns, not curves or bumps,  to slow down cars

d)      On streets surrounding the neighbourhood use traffic circles at the intersections

With these features in place, bumpy rides can be a thing of the past, again.

Ref: Seattle’s traffic safety program: http://www.usroads.com/journals/rmej/9801/rm980102.htm

 

Green them and they will walk – How to get people on a healthy path

Planners feel uncomfortable when reading the stats on the prevailing trends in travel:  Car ownership is growing steadily, personal driving is rising, walking and bicycling are declining, and fewer children walk to school. Also discomforting are the stats about increasing levels of obesity among adults and children and the growing number of cases of lung and other complications due to poor air quality.  This unease propels a strong drive to change how communities are planned and built.  Can different planning techniques stall or reverse these trends?

black to green grid
The uniform car grid morphs into a pedestrian haven

Take air pollution for example, some 18% of which stems from personal driving. For their first 80 years in the city, cars were running without catalytic converters; the unhealthy result was inevitable but also unsustainable.  In comes the “cat-con” car in the 80s that reduces smog dramatically; a simple, inexpensive, regulated device with an enormous positive effect; same city, more cars, more driving but far fewer noxious gases. Planners and developers had little to do either with the problem or its solutions. Looking fifty years ahead, fuel-cell, full electric and hybrid cars, now in production, will send fewer or no gases out the exhaust pipe; same city, no pollution.  When driving must be done, improved technology could make it healthier for people and the planet alike.

But rehabilitating the tailpipe still leaves parents, children and everyone else stuck in their cars driving to nearby or long destinations; an unhealthy routine, particularly for children.  Can people be enticed out of their cars and on to their bikes and feet? What do we know about habits, inducements and their influence? What can a developer do about less driving in a new subdivision?

We know that travel to work accounts for about 40% of all driving and understand that shifting it to other means is a long shot. A CMHC study (2010) showed that there was no difference in the use of transit among eight suburban neighbourhoods (at a mere 9%) even though four were designed to be transit-friendly. Evidently, the decisive factors lie outside the developer’s subdivision plans.

Neighbourhood Opportunity

But at the neighbourhood scale, the developer can have an influence. We know increasingly more and with greater accuracy about design features that could lead to more walking in the neighbourhood.  It all rests on two key concepts: connectivity and permeability.  Connectivity translates into how often people can turn a corner within their neighbourhood. If you can count at least 30-to-40 intersections in a square kilometer, check “good”. More is better.  Permeability is about filtering and preferential treatment. When walkers, joggers and cyclists can keep going beyond where cars can, they get an advantage. Research findings confirm that they prefer it that way.  

Filtered permeability can be best grasped with a drawing. It shows a classic uniform grid (Portland) and one possible modification (right) to benefit pedestrians. The grid with its high connectivity (160 intersections per km) remains the same, but half the streets become paths for pedestrians and bikes. Cars have access to all blocks but not all streets. Permeability favours pedestrians; the joy of walking intensifies.

One more idea added to these two completes the enticement platter – proximity.   It means having destinations nearby such as parks, playgrounds, convenience stores, schools, barbers and such.

A street transformed from car-realm to people haven

The good news

The results are in for these three alluring attributes that would predictably and measurably increase walking.

The CMHC study (above) showed that the two layouts with the highest connectivity  scored 100% more walking trips above the average of all eight neighbourhoods and about 300% more than those with the least walking trips. Not only did they have high connectivity, they also had the highest number of pedestrian paths. The positive influence of the paths is made clearer by the contrasting numbers of a neighbourhood with  a low walking score had just as high connectivity as the ones with top walking scores  but  had few pedestrian paths. Connectivity  works best when complemented with paths.

More and precise evidence comes from a Memorial University (2010) study: of seven neighbourhood designs two stand above the rest with 25%  and 32% more walking in the set; both have paths separate from the regular streets . In addition to increasing walking, they also lowered driving by about 10%. 

An earlier CMHC study (2008) found that the presence of separate paths increased walking by 11.3% and its higher pedestrian connectivity reduced local car kilometers by 23%.  Separately, another study concluded that having a recreation, green space close to home would get more young people walking.

Though locally reduced  driving remains in the range of 78 (lowest) to 81(average) percent of all trips. But we can now trust that it is possible to get more people back on their feet. Green their streets and they will walk.

A Street you can call your own

 

There are two languages in currency that we use to talk about streets: one used by people who live on them and another favoured by transportation engineers. The first expresses our experience of streets and the other describes what each does in a “system”, the transportation network system.

People say they live on a “residential” street or a quiet street, on “main” street or a busy street; words that express an atmosphere, a feeling with always a hint of affection or disapproval. In the “system” or “network” these streets could be “local”, “collector” or “arterial”; neutral labels that ascribe daily car volumes, and imply number of lanes and permissible speeds; people and milieu are out of the picture. This impersonal language stems from a gradual shift in the street ownership from full people ownership to shared ownership with the car, the majority holder.

A narrow exclusively pedestrian street that evokes a welcoming feeling

 Streets were places where people strolled, kids played games and tricks, conversations started, adults traded ideas and goods and, occasionally, a spontaneous display of talent took place; that was the “public realm”, fully owned and used by people. A new owner, the car, now claims rights to the street space and a new craft has emerged to accommodate its requirements. Along with the craft came a new language, the “system” language of classification. When it is translated into design on the ground the result is inhospitable, unfriendly, unattractive streetscapes. 

To shape a welcome outcome when planning a street, the question to ask is: Whose street is it? 

To recover the craft of making streets people bond to, the path may start by rediscovering the meaning of original street words and their story. “Avenue,” for example, originally meant an approach leading to a country house, usually framed by a double row of trees. On the map, such an approach would resemble an impasse, a private lane with just one big house on it.  Later, avenue also meant a spacious road with large, shady trees on both sides. But shortly after, seen as serving primarily the car, it lost its trees and turned into a naked, wide, asphalt-and-cement road with up to 25,000 cars passing by each day.  But this need not be the case.

A similar story unfolds around the boulevards. Originally, they were wide promenades that replaced the obsolete fortifications. Fully landscaped, with spacious sidewalks, they created a country-like atmosphere often enhanced by an occasional park. Street crossing happened casually and leisurely anywhere, at whim. And, following the trace of the defence walls, boulevards circled the city. They were so charming and so conducive to socializing that they even generated a new class of citizens, those who frequented them: the boulevardiers. But being wide and continuous, boulevards naturally fell prey to the service of motor transport, losing the atmosphere that made their name synonymous with charm and leisure time. But this need not be the case when designing new ones.

The avenue story tells us about the importance of quiet and nature in a residential street. And since the majority of streets in every city are residential, there is a lot of opportunity for innovation. First, limit car access to residents-only or make them entirely pedestrian. People-permeable cul-de-sacs or loops do this well. Then use mostly 3-way intersections and use turns to slow cars down. Be generous with tree planting. Nothing surpasses the delight and comfort of a street that has been canopied over by a double row of trees. With these elements in place, majority ownership shifts to residents; and they love it. It sounds almost too good to be practical. Yet this is exactly what was built in Vauban, Germany and it changed our  perception of what’s possible.

The boulevard story brings the message of space, plenty of space – for people. When planning them, change the balance between car and people space. Instead of the now usual four or six car lanes to one half equivalent people-space on the sides, make it four to one or to two. Similarly, when six lanes are allocated to the car, give two or three to people, a la Champs Elysees. This means a virtual linear park on either side of the boulevard with three or more rows of trees and a bike path separate from the road. Add trees and shrubs to a wide median also. The traffic is still there, but now people have plenty of room to walk, stroll, loiter and chat in a charming milieu, their own realm. Alternatively, separate the two streams of traffic by a building block and fill it with a variety of public spaces that make it a predominantly pedestrian area.

Using these techniques, streets can become places that people can call their own.

Closer for coziness, fun, safety and profit.

 Coming back from a cottage vacation, visions of places with the alluring attributes of a cottage emerge: A large lot, fronting a quiet, densely planted street and backing on to a lake, river or woods. Real estate price comparisons between locations of contrasting attributes confirm this craving. Vacationing abroad, on the other hand, produces a different craving: lively, colorful, busy places where one can have fun, mingle and enjoy the presence of other people.

 People bond to both kinds of places and want both. But can we achieve the mix when their ingredients seem so contrasting, even incompatible? Looking around for clues, we find that the key to the blend is “moderate closeness”.

 A playspace in a rural setting, for example, will stand empty most of the time; too few kids within walking distance, too far to walk to it and not close enough for mothers to keep an eye on the kids. The same would be true of the streets; mostly empty. Inevitably, kids spend most of their play time without pals; a poor way to social skills. Parents too live secluded lives in that milieu. Clearly, the houses are too far apart to create the “critical social mass”. 

A play space as a focal point in a compact neighbourhood

                          A similar situation, but for different reasons, arises at the other end of closeness – apartment living; too few kids, much isolation and very little interaction. The view from the balcony may be stunning but from the keyhole viewer it is precautionary.

Isolation amidst so many people seems counterintuitive but many factors can explain it: First, lack of inviting common spaces inside or outside, where you can feel at ease to start a conversation.  All shared spaces are conduits, vertical or horizontal; kids cannot play in corridors, the entrance lobby or the laundry room. Then it is people statistics. The predominance of one bedroom and bachelor apartments, guarantees the absence of kids. Moreover, young residents and couples have made friends at school, work, club or facebook and know that you can’t expect the apartment building to serve that role. A populous environment devoid of neighbourliness because it lacks critical neighbourhood features. It need not be so.

 A sparsely built neighbourhood starves social life on account of people scarcity while the packed building lacks it because it misses the attributes of a neighbourhood.

 What environment would strike the perfect balance? What is the “critical mass” of a flourishing neighbourhood?

 And then the risk of antisocial trespassers and intruders pertains.  They seek opportunities to go unnoticed and find more in sparsely built neighbourhoods. Closeness reduces these opportunities.  Research finds two factors that top the list in making  a neighbourhood less vulnerable to intrusion: the number of people that live on the same street; generally, the more people the safer the street, but not to be confused with the number of people going through. The latter may increase the risk as the number goes up. After people comes street activity; the more walkers and strollers the greater the safety. 

A cul-de-sac permeable for pedestrians only can be a play and social space

Researchers agree that the magic number for a friendly neighbourhood is in the range of 45 to 60 people per hectare.  Translated into homes, at 2.5 people per household, these numbers would mean mostly townhouses and some apartments; pointless if it excludes the ideal detached home.  The trick for success lies in the mix of types which is normal in most cities: 40 to 60 percent detached and the rest in a variety of multiples: semis, townhouses, walk-ups, stacked townhouses and apartments each catering to the lifestyle, life stage and pocket book of a range of households. Even singles can up the people count by including accessory apartments for relatives. This mix is also a profitable proposition: The development widens its client base (faster sales), increases the total number of units (higher yield) and raises the level of customer satisfaction (free, credible promotion). What’s more, it saves home and travel energy.

 Reaching the critical people mass, however, is only half of the job. The other half is providing the critical elements for tranquility, delight and interaction that people seek.

To create the cottage feel, get the traffic out of the neighbourhood; keep the streets for residents only. Hide away as many cars as possible. Enhance the site’s natural features and make them work for everyone. Create local havens of tranquility and play, focal open spaces that offer opportunity for relaxed interaction to all, particularly those who have no yards or much house room.  Plant the streets heavily, enough to make trees visually more important than the buildings. Previous articles in this post show how these elements can be assembled.

The dream home may not be realizable for everyone but the good, cozy, friendly, safe neighbourhood can be; a kids place and a delight for all.  And the developer delights in their pleasure.

 This article first appeared in the “Home Builder” magazine, September 2010 issue

A Fused Grid Neighbourhood in Construction

A new Calgary neighbourhood shows the features of a good, Fused Grid  neighbourhood  

In Calgary, Alberta work has begun on a new 64 hectare subdivision that will put leading edge urban planning walkability principles into practice.  Named Saddlestone, the new community uses the Fused Grid model.  

http://www.genesisland.com/land/saddlestone/community-map.html 

The Fused Grid model is a new way of arranging streets and open spaces to allow for a high level of pedestrian connectivity, while limiting the amount of automobile through-traffic within residential areas. It blends the best features of the gridiron system common in traditional urban areas and the looping streets and cul-de-sacs of more conventionally designed suburban areas. It does this by shifting most of the traffic to continuous through-traffic roads around the perimeter of the neighbourhood, while making streets discontinuous within the neighbourhoods.   

land use concept
Land Use Concept of the 160 acre neighbourhood

The key in making this arrangement highly walkable is the use of strategically placed footpaths, linear parks and open spaces to ensure a continuous pedestrian network within the neighbourhood. This results in slowing traffic around residential areas while leaving pedestrian flow uninterrupted, with direct, efficient and pleasant walking routes to parks, transit and amenities.  

The integration of the Fused Grid model into plans for Saddleton began in 2004, when the developer, Genesis Land Developments, began collaborating with the CMHC on the creation of a site plan that incorporated the model’s key principles. Municipal approval for the plan was given in 2008, at the conclusion of a process that included meetings with city officials and revisions to the initial plan, submission of a full development application, a public open house, a presentation to the Calgary Planning Commission and a public hearing of City Council.  

Saddleton’s application of the Fused Grid model is a significant step forward for this planning approach. It will demonstrate the model and its benefits in a concrete fashion and will be of great interest to municipalities, developers, home buyers, active living/transportation advocates and others as the new community takes shape.  

Walking didtance to parks

Increasing pedestrian connectivity while limiting vehicle connectivity within neighbourhoods, as the Fused Grid does, has been shown to improve rates of walking and physical activity for residents. A research study compared rates of walking in neighbourhoods with different levels of pedestrian and vehicle connectivity, including neighbourhoods with and without traffic calming measures, such as “diagonal diverters” and streets closed to cars but not to pedestrians and cyclists.  

The research found the highest rates of trips by foot (18 per cent) in areas where pedestrian connectivity was higher than vehicle connectivity. This compared with 14 per cent for areas with high levels of both pedestrian and vehicle connectivity and 10 per cent for areas with low pedestrian connectivity.   

Extesnsive network of paths add to the street connectivity

  The Fused Grid’s positive impact on walking is not at the expense of efficient traffic flow— a traffic simulation study showed that the Fused Grid model would allow an efficient flow of traffic and is superior to several other street layouts. Both pedestrian comfort and car movement are accommodated with sizeable reductions in the risk of collisions. Most street intersections on the site are 3-way which according to recent  research studies are the safest. 

In summary, neighbourhoods like Saddleton could enhance active living, reduce accidents and lower harmful car emissions. Moreover, they would create a milieu that blends nature, a restorative feature, in an urban setting.  

FUSED GRID: Open spaces with a triple function: recreation, pathway node and rainwater filtration are  part of the site plan:   


Three research highlights provide a quick tour of the ideas behind this new neighbourhood and the Fused Grid planning model:  

Canada Mortgage and Housing Corporation.  Breaking Ground: A Fused Grid Neighbourhood in Calgary. Research Highlight: Socio-economic Series 08-020. December 2008. Available at: www.cmhc.ca  

[ii] Canada Mortgage and Housing Corporation. Giving Pedestrians An Edge — Using Street Layout to Influence Transportation Choice. Research Highlight: Socio-economic Series 08-013. July 2008. Available at: www.cmhc.ca  

[iii] Canadia Mortgage and Housing Commission. Taming the Flow — Better Traffic and Safer Neighbourhoods. Research Highlight: Socio-economic Series 08-012. July 2008. Available at: www.cmhc.ca

The True Public Realm

Same city(Montreal),  two streets and two strikingly different approaches to the public realm.

Both streets are intensely public and encompass a range of uses but are predominantly gathering and socializing spaces.

On the right, in the common, inherited grid, the public fucntion takes over the entire narrow sidewalk leaving no space for pedestrians. Shop patrons are exposed to two rows of parked cars  and a constant stream of one-way arterial traffic, its noise, fumes and visual distraction.
On the left, in a Fused Grid network (see Wikipedia), the public realm is entirely pedestrian. There is practically no limit to the expansion of the seating area. Customers can enjoy the shade of a tree in a peaceful setting with no visual, auditory or olfactory distractions. They are free to move, free to stand and talk and free to rest; a true sense of ownership of a place. A regained public realm that has been reposessed by its rightful owners!

Streets as currently used suffer the inevitable dominance of the car, incontestably the more powerful. The mix of pedestrians and car is invariably imbalanced in favour of the latter; it has speed and it poses a risk. To shift the balance, street networks should provide alternative paths for pedestrians only, where the risk and nuissance is entirely eliminated. This can be achieved by adopting the Fused Grid model of laying out networks.
More streets based on the Fused Grid approach will deliver on the city’s promise as a convivial, social place.

Beloved and Abandoned: A Platting Named Portland

In the 4000-year history of the grid, American incarnations are relatively new, appearing first about 300 years ago, frequently as a simple, orthogonal and often square (such as Portland’s) ‘Hippodamian’ grid, named after the planner of Miletus around 473 BC (Fig 1).  

A session in the recent 2009 New Partners for Smart Growth conference focused on ‘The Beautiful American Grid — the Embodiment of Smart Growth,’ which lamented the fact that the grid ‘gets no respect’.  

 This alleged lack of respect seems at odds with most planning literature, which extols its virtues and mirrors prevalent New Urbanist practice. This disparity between theory and practice simultaneously confuses the practitioner and frustrates the theoretician. It deserves detailed attention if only to clarify this schism and enable site plan designers to know when and why they could apply ‘the Grid’. Clarity about its attributes may also open the way for its regeneration. 

Recognition and Respect
Current planning literature brims with references to “the grid” in juxtaposition with curvilinear and dendrite conventional suburban layouts. The “grid” as a network concept has been widely accepted and is now regarded as a superior geometry for laying out greenfield and infill sites.  

 

Figure 2. Portland’s (Hippodamian) Grid overlaid on a Virtual Earth bird’s eye view of Pearl District. The centre lines of streets intersect at 260 foot intervals.  

For example, in 1992 we read that “Streets ought to be laid out largely in straight segments, as they were until the 1940s. After all, the vast majority of our successful towns and cities, from Cambridge to Portland, were laid out this way.” (Duany). The grid gets credit for city success, at least by inference, but is this credit warranted?  

Portland’s network offers an instructive example for discussing grids because of the grid’s nature (an unadulterated Hippodamian grid and the densest of all American city grids (Fig 2, MS Earth), its size and the City’s planning celebrity status. We read again that “Portland owes much of its success to its tiny blocks that create an incredibly porous network of streets, each of which can be quite small as a result” ( Jeff Speck, 2005). In this praise, it is not simply the grid in general, but the small blocks in particular that impart success.  

In articles, project brochures and city planning reports “the grid” stands alone; the other contestant, mid-to-late 1900s suburban networks, has been wholly discredited in mainstream planning. One can hardly pay more respect.  

Affiliation and Affection
Portland’s street grid pattern has attracted attention indirectly and directly. Indirectly, because the City of Portland has taken many first-ever, brave and decisive measures to manage growth, and cities and planners hold it up as a model of civic vision. Inevitably, attributes of the city — such as its grid — are seen by affiliation as paradigmatic.  

Personal testimonies of visiting planners who express adulation for Portland add a second indirect layer of attention. Constantly on the outlook for an ideal urban pattern, planners list Portland as a favorite and some boast “I love that city!” with emotion. Recently, a local movement to rename the city in order to project these strong emotions was set in motion. But strong feelings such as these may be entangled between actual attributes and personal associations, hard to unravel for practical purposes, as other cities also share such emotional investment, at times.  

Urbanists and romanticists have expressed equally strong sentiments about Paris, London, Barcelona, Curitiba, Amsterdam and Venice. Of the six, only Barcelona adopted the Hippodamian grid in 1859 for its vast expansion, and Venice, without a classic grid, is the preeminent pedestrian haven, yet neither city matches the urbanist’s praise for Portland. Whatever the mix of reasons, Portland dominates the American planners’ imagination feelings and talk. Disentangling this intangible realm can be an elusive goal; grounds and figures on the other hand may produce tangible results.  

Grounds and Figures
Pragmatic reasons may play a part in this adoration. The extreme simplicity of the plan, for example — a uniform, perfectly orthogonal, expandable checkerboard — could be one. As a drawing, the plan has a feel of flawlessness, the appearance of perfection, particularly in contrast with labyrinthine medieval town plans or recent bewildering suburbs (Figure 3). When this perfection is combined with a pleasant experience on the ground an indissoluble match is made.  

 

Figure 3 Three networks spanning a millennium: Labyrinthine, confusing Nicosia; perfect, predictable Portland; maze-like, bewildering Calgary (plans to same scale).  

The degree of connectivity of the street network could count as another practical reason. ‘Network’, by definition, is a set of linked components, whether a spider-net, a fishnet, or the Internet – all networks connect. What distinguishes them is the manner, geometry and frequency of connection: leaf, tree, blood vessels, telephone and web networks are dendrite, hierarchical (fractal) but fishnets are not. Portland’s is a dense fishnet with nodes at every 200 feet, which produce 360 intersections per square mile — the highest ratio in America, and 3 to 5 times higher than current developments. For example, older and newer areas in Toronto, typical of most cities, range from 72 to 119 intersections per square mile in suburbs and 163 to 190 in older areas with a grid. As connectivity rose in importance as a planning principle, Portland’s grid emerges as a supreme example.  

Coupled with connectivity, its rectilinear geometry is indisputably more advantageous for navigation on foot, car or bike than any alternatives. Visitors often feel lost and disoriented in medieval towns and in contemporary suburbs and this feeling leads to anxiety and even fear and a sense that all is not well.  

What explains why the simplest, purest, most interconnected and easily navigated rectilinear grid, in spite of all the praise, has, evidently, not been applied in any contemporary urbanist plan, whether infill or greenfield? What caused the disaffection?  

The Disaffection: Speculation
One clue comes out of a believable legend about Portland’s grid. Unlike other American cities that were laid out by erudite generals or governors, such as Oglethorpe (Savannah, 1735) or William Penn (Philadelphia, 1701), Portland’s plan was apparently conceived by scrupulous speculators who reasoned that more corner lots would yield higher profit on the land investment, hence the maximum number of intersections. Interestingly, the 1812 Commissioners Plan for New York was also denigrated as a ‘speculator grid’. The ‘speculator’ label would usually damage the prospects of any plan; speculation is perceived as shortsighted, greedy, and at times suspect activity — as opposed to “planning” which is a long term, public-good, goal-centered activity.  

Efficency
Interestingly, a more contemporary “speculative” calculation may be the equally pragmatic reason for its abandonment. 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. A recent comparison of an existing 338 hectare subdivision’s curvilinear pattern to an overlaid TND plan showed that the land for roads was respectively 88 and 122 hectares or 40% higher for TND with a corresponding increase in infrastructure costs (IBI) (Figure 4). No developer or municipality would savor this arithmetic.  

In business districts, small blocks may force buildings to gain height and thus increase the per block net density, a financial advantage, but the gross density of such district would be comparatively lower than that of another with larger blocks and similarly tall buildings. On balance, more buildable land means more opportunities to build, tall or otherwise, and therefore more rentable space, revenue and activity.  

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. 

 

Figure 4. Comparative Building Block sizes of Portland, Suburb and Suburb TND (partial plans). (Note the total eclipse of 4-way intersections in both newer plans).  

Aesthetics
Reasons that relate to urban design aesthetics can also be seen as contributing to the disaffection with Portland’s platting. Starting with Camilo Sitte in 1892, who said categorically: “Artistically speaking, not one of them [grid patterns] is of any interest, for in their veins pulses not a single drop of artistic blood.” The string of unfavourable comments continues to 1994 with “Upon reflection, we realized that the developers [who hired us] had a valid concern, one related to the shopping-center developers’ understanding that human beings do not like endless vistas.” (Duany). This insight into people’s behaviour was confirmed by academic research recently (Ewing). Add to this backdrop the common, if superficial, perception of cookie-cutter planning and endless monotony, and distaste for the Portland grid emerges, particularly in eclectic urban designers. 

Environment
Since Ian McHarg’s 1969 classic book, Design with Nature, planners have been keenly conscious of the potential negative impact of land development on natural systems. Soon after, pioneering projects, such as Village Homes (1975), responded to this concern. Recently we heard: “The New Urbanism does not do grids that quash nature” (Duany 2001) followed by a movement for Low Imprint New Urbanism in 2007 (LINU). Permeability and rain water management have emerged as key indicators of a plan’s fitness. On these measures, the Portland grid occupies the negative end of the spectrum of impermeability with the most road surface. With environmental concerns and regulations rising to the top of the planning agenda, any low performance plan would be disfavoured.  

Compact, dense development, such as happens in downtowns, lowers the pressure for expansion and its incursion on natural environments. However, though a city’s bioregion may be better off, the dense downtowns still exports large amounts of storm water and, with it, pollution. No part of the city need be absolved of the imperative to curb outflow; greening unnecessary asphalt is a viable first step. In that vein, Portland has retrofitted some streets. 

 

Safety and mobility
Practical considerations about traffic flow and safety may also undermine its presence in contemporary plans. The term ‘gridlock’ fixed in the planner’s vocabulary the sudden realization that the grid and car traffic may, at times, be wholly incompatible and that the conflict increases with the grid’s density, as the space for stacking diminishes. The alternative to the grid, 3-way intersections, has been established as the safest and as enabling good flow. (Lovegrove, IBI). When streets in a grid become alternating one-ways, as in most downtowns, they create virtual 3-way intersections throughout an entire district, and achieve both safety and flow. Virtual 3-ways result also from traffic circles, as in Seattle and Vancouver, and from roundabouts, now gaining acceptance in America.
   

 

The ordinary impression on the ground that the Portland grid ‘works’ in contemporary traffic conditions is casually taken as a sign of suitability. This view obscures an entire century of engineered physical, mechanical and management adaptations which are overlaid on the 1866 platting. Remove these (in a thought experiment) and imagine the outcome. Clearly, an ill-suited geometry is made to work with interventions such as dividing lines, medians, traffic signs, traffic lights, directional signs, bollards, street widening, one-ways, traffic circles or roundabouts and many others.  

Abandoning the Grid
The current map of Portland shows the transformations the city’s grid has gone through since the 1866 platting, a century before environmental and traffic issues drew the spotlight.
  

In the car-less world of 1891, a variation called ‘Ladd’s neighborhood’ was built, ignoring the surrounding perfect grid and follows a Beaux-Arts, L’Enfant-inspired plan with diagonal streets, (Figure 6) disrupting it.  

   

Figure 6. Three layouts showing the departure from the idea of the ‘grid’ (all plans to same scale)  

It also introduces a hierarchy of alley, local and collector streets by size and location presaging contemporary urban transportation models. In a sea of formless, perfect uniformity, it brings an organizing module (about 160 acres) that anticipates Perry’s Neighbourhood Unit (1923), which also assigns a hierarchy to its streets, and, likewise, protects it from through traffic.   

Transformations also happened within and beyond the 1866 city outline over time: blocks doubled or tripled in length, some streets became discontinuous and, later, curvilinear streets appeared. More recently, some of the city streets were closed to cars, effectively doubling the block size and introducing a pedestrian space in the middle; an adaptation that produces a high quality public realm which is in short supply in an extensively asphalted grid. All these transformations occurring next to an “ideal” grid leave a trail of desertion which is hard to reconcile with the affection found in literature.  

Conclusion
For reasons of land efficiency, infrastructure cost, municipal expenses, rainwater management, traffic safety and flow, and the demand for increased pedestrian share of public space, the praised, pure Portland platting will likely not find new followers.
  

(This article first appeared in Planetizen.com, October 09.) 

Unplanned Best Urbanism, Adaptive Mix of Uses

Unplanned Urbanism - adaptive mixed use

 

 

 

 

 

Postponed, adaptive mixed use and walkable neighbourhoods.

At the perimeter of this early 20th century city stood proud, simple or embelished houses on a quiet street; no stores or traffic in sight. Most people walked to destinations as transport  options were limited to foot, carriage (for the elite) and the tram, at some distance.
Fifty years on, as the city expanded beyond this edge, the street became a main artery, traffic increased and rendered its environment less desirable for living.  The houses transformed to a variety of uses: Low rent or rooming units upstairs and transient commercial uses on the ground floor. Inadvertantly, what emerged, sometimes following painful fights with City Hall, is a walkable mixed-use that now city planners promote as the ideal way to build neighbourhoods under the banner of New Urbanism.  What took fifty years of natural progression and friction to develop in the middle of the city’s area, planners now want instantly in every new neighbourhood at the periphery, because, they argue, it is “good urbanism”! Something is amiss in this picture.

Though fevereshly advocated, this image would still be repugnant to many planners – too messy. Instant mixed-use, and Main Street  built to high standards of harmony is the preferred alternative. And, importantly, no rooming units for transients above the store. Transients are seen as an anathema to a good city image.

It would be a good idea to reconcile  expectations, history and reality in the City planning books

Goodbee Square:The Quest for a Contemporary Urban Pattern

Goodbee Square, a recent project by Duany Plater-Zyberk and Company constitutes a fertile departure from previous DPZ plans, integrating novel elements of traffic flow, pedestrian movement, traffic safety, park allocation and distribution and storm water management into the regularity of a simple grid. As a change in direction, and because street patterns are the most enduring physical element of any layout, it could potentially contribute to systematic site planning and, consequently, deserves a closer look.                                                                                   

The street pattern
Unlike the classic street grid of Portland (Fig. 1, left), the Goodbee Square street layout (Fig. 1, center) impedes north-south vehicular and pedestrian movement, although pedestrians are given another option (Fig. 2). Though the network is entirely interconnected, north-south movement becomes circuitous, indirect, and inconvenient, making driving an unlikely choice and vividly illustrating that interconnectedness by itself is insufficient to facilitate movement. The 3-way intersections limit through traffic, a lesson incorporated in TND (Traditional Neighborhood Development) and reminded of recently at Seaside.


Fig. 1 Three layouts and three patterns (all plans same scale based on GOODBEE SQUARE)

Were we to apply this street pattern to a town center in nearby Covington or New Orleans, it would be entirely unworkable. Drivers would have serious difficulty reaching local destinations, and pedestrians would find their walks to be disorienting and unnecessarily long. But its very unsuitability for an urban center justifies its current usage as a suburban or ex-urban pattern.

As a principle of organizing circulation, it constricts traffic and confines expansion, unlike earlier simple street grids like Portland’s regular grid or Savannah’s cellular grid which, can be expanded in both directions without loss of functionality. If expanded to a large urban or suburban area, the Goodbee Square plan, with the discontinuous north-south roads, would severely limit traffic dispersal, a base for advocating regular grids. The Savannah and Portland grids both allow traffic to disperse in both directions, a feature that makes them equally applicable to city centres and to suburban locations.

The Goodbee Square street pattern eliminates unsafe four-way intersections within the neighborhood. The frequency of intersections with the main artery contradicts current traffic engineering practice, which subscribes to the notion that longer blocks reduce stop-and-go inefficiency and driver frustration; provide more uninterrupted movement space for pedestrians; opportunities for commercial façade size and treatment and increase on-street parking spaces which facilitate drivers becoming pedestrians and then shoppers. Longer blocks move cars more efficiently through Main Street, accentuating its role as a busy, vibrant thoroughfare. Perry’s Neighbourhood Unit, a recurrent urbanist prototype, includes such blocks.

The north-south movement constraint, the lack of traffic dispersal and the frequency of intersections on Main Street contradict the usual practice, and require a fresh look at the Goodbee Square street network as an urban pattern.

The pedestrian network
A welcome attribute of the Goodbee Square plan is its pedestrian network which rejects the notion that streets are sufficient and suitable carriers for both car and pedestrian traffic. The plan has an independent north-south path network, which compensates for the inconvenience of the street network and favors pedestrians over motorists (Fig. 2). The footpaths are almost straight and cross parks frequently. Recent research confirms that directness and pleasure, as well as path independence from roads, are important attributes for enticing and enabling pedestrian movement.


Fig. 2 Exclusive pedestrian paths in three plans as they would function currently

The principle of providing separate pedestrian paths could transform current site layout practice, which uses streets almost exclusively as the connectors for all mobility modes.

With respect to pedestrian movement, the Goodbee Square plan improves on that of Savannah and is a dramatic departure from the Portland plan, implemented in the18th and 19th centuries respectively, when the entire street and space network was a pedestrian domain and no other modes were dominant.

Parks
The Goodbee Square plan differs from previous DPZ plans in the number and location of its many charm-infusing parks which are regularly arrayed along streets with no attempt at civic monumentality or visual significance, unlike Savannah’s plan, which locates parks within an 8-block cell as a focal point for each neighborhood. Both Savannah and Goodbee Square use parks as a means to enhance the pedestrian experience by placing them along pathways. The Portland plan has no obvious park strategy.

 
 
Fig. 3 Parks and their distribution. (the Portland parks are indicative only) 
 
Both the Goodbee Square and Savannah plans create a delightful environment with most residents near a park or with park views. Savannah, however, does it with greater economy of means; four parks compared to nine in Goodbee Square within a similar area (Fig 3). While parks are generally welcome, land value, urban density, unit yield, unit price and municipal maintenance cost considerations would normally lead to reducing their number.
The quest beyond Goodbee Square
Can the advantages of the Goodbee Square plan be retained while alleviating its limitations? We believe that a plan combining the main characteristics of the Portland, Goodbee Square and Savannah could do just that. If feasible, such a pattern can then be applied to many 21st century site plans, much like the simple grid pattern found in hundreds of North American plans over the centuries.
The Goodbee Square plan, an offset grid closely resembling the Flemish Bond brickwork pattern, would be the starting point for a new template, meeting the following objectives through proven planning strategies:
  • Keep vehicular traffic safe with a high proportion of 3-way intersections
  • Reduce cut-through traffic by similar or other means
  • Improve traffic flow in both directions using Savannah’s cellular structure
  • Improve traffic dispersal by a car-sized grid
  • Improve pedestrian mobility utilizing Goodbee Square’s path separation
  • Make parks a focus as in the Savannah cell
  • Improve land use efficiency and unit density

As an experiment, we combined the Flemish bond pattern (Fig 3), with the cellular organization of the Savannah plan by imagining a two-directional Flemish Bond. This new stencil emerges as a re-invented Savannah cell with a geometry that satisfies all the requirements for vehicular circulation and pedestrian movement; Jefferson, Oglethorpe and Hippodamus meet at the square.

  

   

Fig. 4 From a unidirectional Flemish Bond towards a contemporary network pattern  

As in the Goodbee Square and Savannah plans, all intersections within the neighbourhood are 3-way, satisfying the first two objectives. (Fig 4). The cellular structure creates a car-scaled grid that moves and disperses traffic, meeting the third goal.

Every block faces a park, generating a delightful milieu. Separate, strategic through-the-block paths achieve high pedestrian connectivity in every direction, and short streets provide easy access to nearby through-routes for drivers.

Efficiency of land use is achieved by subtracting half the Goodbee Square through-the-block path segments; reducing parks from eight to four, and reducing street length in equivalent areas.

 Goodbee5
Figure 5. Recombination of Savannah and Goodbee Square site plan elements (red lines: pedestrian paths; blue dotted lines: car lanes or greenways)  

The interface with Main Street now includes two long block faces for every short face, improving traffic flow, parking and pedestrian safety and enjoyment.

The Goodbee Square plan lays the foundation for the next step in the search for a contemporary pattern which might be called a “fused grid,” as it combines car dominant and pedestrian dominant paths to form a complete, amalgamated network.  

 


This article first appeared in Planetizen.com August 24, 09. Doug Pollard, Barry Craig and Ray Tomalty contributed to this article .

“Urbanesque”:Town square amidst asphalt

  

 

Urbanesque: An imperfect mix of 19th century urbanism with 20th century technology.

Like the Promenade Shops in Saucon Valey ( see earlier post) this square, “La Grande Place” , is surrounded by a sea of parking.

While this inner suburb for 9,000 people has a main access road, a boulevard, no commercial uses flank it. Instead, at the end of the road and in the midst of a large parking area stand four building forming a “square” with all the historic references to an Italian  “piazza”. To make things worse, the piazza is bisected by two roads; one has to cross them to reach the flannking buildings. Moreover, its entire north side backs on to a golf course; a contrived sense of a commercial cetre. Bollards have been used to detter cars from going on to the square; a sure sign of design failure. Bollards become necessary  in existing towns where the street design is inherited and inalterable. The designers of this plan had plenty of freedom to devise a car free space the size of a block without reverting to mechanical devices.

This layout, a parking lot that surrounding a shopping street (open or enclosed), can be found in many suburbs and has been criticized as anti-urban. This scaled down version, is found in one of the acclaimed New Urbanist developments – Bois Franc – in Montreal; an ironic twist of urbanism and suburbanism, of urban aesthetic and car functionality.

An ideal world for upscale living based on the car.
(bird’s eye view of plaza by Bing)