A new model for planning sustainable cities

A great deal has also been written about what can be done to make our cities healthier and liveable. It is well known that these types of cities are characterized by a series of basic design principles and attributes; for instance, by including:

• compact and mixed-use developments;
• environmentally-friendly buildings;
• a wide range of housing choices;
• a high level of transportation connectivity;
• alluring opportunities for residents to socialize and exercise;
• and attractive options for residents to walk, bike, or take the public transit to go to the places they need or want to go every day —without having to rely upon their private cars at all times.

However, much less has been written —and documented— about when and how, in the planning and design process, we should implement those principles and attributes.

Obviously, the street-layout and site plan configuration phases at the neighbourhood and district levels can be the most critical stages of the planning and design process to ensure healthy and liveable developments.

And it is exactly at this stage when planners, policy makers, politicians, developers, designers, and residents should be aware of the full range of options that are available to them and diligently ask:

• How can we make our project more walkable?
• How can I increase mobility and connectivity in my project?
• How can we boost pedestrian and traffic safety in our project?
• How can I make public open spaces more efficient, more lively and more attractive so that residents use them more often to socialize, exercise and engage in civic activities?
• how can we maximize land efficiency in our project so that we can make it more sustainable?

Recently, when I was looking into the literature related to one of my projects, I was fortunate to have found answers for all the questions listed above —and many more. They were in a new book titledRemaking the City Street Grid.

This book is informative, thought-provoking, comprehensive, and contains numerous analyses and discussions of real-life examples where a variety of healthy and liveable aspects have been successfully implemented.

It also features four detailed case studies of a variety of applications and designs, three of which are located in Canada —one in each: Calgary in  Alberta, Stratford in  Ontario, and Kelowna in British Columbia— and one in New York City in the U.S.A.

In the book, I also learnt about an interesting street grid planning model called the Fused Grid —which I believe community planners, policy makers, politicians, designers and developers can use wisely to create healthy and liveable neighbourhoods and city districts.

The Fused Grid is a neighbourhood and district street layout model that combines the geometry of inner city grids —rectangular blocks— and the geometry of conventional suburbs —loops and cul-de-sacs.

This fusion results in retaining the best characteristics of each of the two geometries and none of their disadvantages, and in enhancing both the functioning and the quality of the neighbourhood and district environment.[1]

What the Fused Grid accomplishes   

The Fused Grid combines a continuous grid of roads for district and regional connectivity, and a discontinuous grid of streets for neighbourhood safety. The discontinuous grid of streets is supplemented by footpaths that connect all streets —thus turning the neighbourhood into a fully connected pedestrian realm. Together, the continuous and the discontinuous grids accomplish the following:

• Optimize the use of land for streets
• Secure tranquil and safe neighbourhoods
• Increase the potential for social interaction
• Reduce the amount of impermeable surfaces
• Optimize infrastructure
• Assist district and regional traffic flow
• Encourage walking while positively discouraging short-distance driving, and
• Provide opportunities for rain water management

The Fused Grid anticipates and channels land intensification and mixed uses by creating a zone with high potential for change. It can also accommodate adaptations to future traffic demand.

Saying in it in a very simplified manner, the Fused Grid balances both the needs of the pedestrians and the needs of the motorists while responding to the quest for economic efficiency and to the need for environmental stewardship.

Exhibit 2: An aerial view of another Fused Grid city district example showing a full neighbourhood of four quadrants and its intersecting mixed use zones.

Basic design principles for the Fused Grid quadrant 

When using the Fused Grid model, there are three basic design principles for structuring a quadrant —and from them, and their combinations, several additional variations have been developed, and many more are possible:

• The first principle is that streets within the quadrant do not traverse the quadrant; they either stop within the quadrant or return to the perimeter of it
• The second principle is that all the streets in the quadrant must be connected with pedestrian-bicycle pathways. This makes the entire quadrant (neighbourhood) easily traversable on foot or by bike
• The third principle is the character, configuration and functioning of the neighbourhood open space. The neighbourhood open space must indeed accomplish the following: serve as the social and focal point for the neighbourhood; serve as its recreation and play area; function as a passage and crossover point for the pedestrian-bicycle pathways; and enable continuous walking throughout the neighbourhood without any street crossings.

Key findings of two Fused Grid studies

One study[2] examined two measures: relative route directness; and relative network density across walking and driving modes —both of which have associations with odds of walking, odds of driving, distance walked, distance travelled by vehicle, and number of trips. The results suggested that increasing connectivity on foot relative to in-vehicle travel, increases the likelihood that people will walk more and drive less. And that these results are consistent with the premise of the Fused Grid.

Another study,[3] designed to make a comparative assessment of the transportation impacts of three different district street layouts —conventional suburban, neo-traditional, and Fused Grid— found that the Fused Grid layout exhibits the best traffic performance, particularly with increasing density of developments, and that this occurs for two reasons:

1. the hierarchical street system in the Fused Grid layout provides for efficient traffic flow into and out of the neighbourhood; and
2. the Fused Grid major collectors are designed as one-way couplets, [which] reduces the number of signalized intersections required, and streamlines traffic signal cycle timing.

The conclusions of one of the Fused Grid case studies[4]:

 “This case study highlights two important points: that the fused grid model can be applied to urban settings with equally beneficial outcomes as in a suburban milieu; and that its application can produce considerable benefits in terms of land-use efficiency, connectivity and walkability, active transport, fitness opportunities, noise reduction, clean air, restorative ambience and community cohesion.”

“It has been said that a good place for kids is a good place for everyone. Stuyvesant Town provides proof: it has a much higher percentage of families with children (36 percent) than the average in New York City (22.7 percent). Such a statistic shows that a central city district can be a good place to raise a family, if laid out as a fused grid.”

This article is published in collaboration with Sustainable Cities Collective. Publication does not imply endorsement of views by the World Economic Forum.

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Author: Luis Rodriguez is a housing and urban planning consultant and author, a Member of the Royal Architecture Institute of Canada and a former senior researcher with Policy and Research at Canada Mortgage and Housing Corporation (CMHC) in Ottawa.