These are some developing thoughts about how to plan and grow cities.
Growing, as opposed to planning or building, is important as the cities we think of as successful today weren’t designed in one attempt, or built in a few phases, but grew over many years.
There’s a lot of criticism of the way cities currently respond in a physical way to their wider economic and social context. It is arguable that planning in its current form has not and does not achieve the objectives it sets out to. Many cities are fragmented by infrastructure, set out in low density single use zones, suffer poor health, are difficult to grow, irresponsive to market conditions, irresponsive to their residents, or uncoordinated in outcome.
Some of this criticism relates to the unintended consequences of design decisions. Cities are complex systems of many interacting components and identifying these impacts many years ahead is very difficult.
It is arguable that the Introduction of zoning to make cities healthier has had the opposite effect. Moving factories out of city centres may reduce one pollutant in the air, but as industrial uses tend to require large plots that create too few employment opportunities to sustain public transport, many workers now drive to work at peripheral locations. This increases traffic, adds a different mix of pollutants to the air and can make streets less safe for pedestrians and cyclists.
Because cities are complex and exist within a much wider set of conditions, there is also a socio-economic context to consider. It happens that the approach to zoning cities and prioritising higway infrastructure overlapped with a trend within food production where it became increasingly Industrialised/commercialised. This resulted in food being bulked out with cheaper ingredients that had a major impact on health if consumed in high quantities (corn syrup for example). This was also combined with no real income growth for large sectors of the EU and US demographic as many lower skilled industrial jobs moved to Asia.
One of the results of this is that it is harder to eat healthily for a lower income demographic, who, thanks to planning decisions to move their industrial employment, now have less choice of where to work and how to get there. One of the changes overlapping with this has been worsening health, evidenced by increasing levels of obesity and associated illnesses – diabetes, heart disease, etc.
Top row: Polluting city centre factories moved to the edge of cities before large scale manufacturing shifted to other continents, leaving the original buildings to be re-developed as unaffordable housing.
Bottom Row: Garden city plan* separates polluting uses from residential, data showing relationships between density and public transport viability**, change in US cities with density to support public transport***, shift in world GDP**** and rates of obesity****
The subject of reducing the impact of unintended consequences needs to be thoroughly unpacked elsewhere, however it is worth reiterating that the silo-isation of city planning disciplines does not help. The use of analytic and predictive modelling could help address part of this issue.
Two other sides to this discussion are the way cities are planned and regulated, and the approach taken to city design.
Planning and regulation
There are arguments that the current mechanisms for managing cities do not work. Because Cities are big and complex and slow to change, it is very difficult to achieve improvements within the political term of an elected Mayor for example. This makes it easy to criticise the achievements of the current Mayor but also easy to claim current successes, which may be the result of previous decisions.
Committing to large infrastructure projects is made more difficult by a media who report astronomical costs, rather than potential benefits, making long term infrastructure projects potentially unpopular with voters who have access to mass communication tools such as social media. This makes it near impossible to invest in major infrastructure projects (the expansion of Heathrow for example).
Within this context, it is not difficult to see how the priorities of a Mayor could be skewed by the process of election and maintaining popularity.
Conversely, in authoritarian regimes, a Mayor may be picked by the head of state safe in the knowledge that they have time at least equivalent to a democratic term available if not more. However when a Mayor is replaced, often the first thing to happen is to stamp their mark on the city by re-making the City plan. This also creates fractures in the city, reducing continuity and making it very difficult to deliver positive change.
Both political systems therefore have issues in terms of their impact on cities, without beginning to look at the impact on wider society, nor the way that the city regulating authorities are organised (how bureaucratic, disjointed or corrupt they may).
One reaction has been the argument that proposes completely de-regulating cities to allow them to respond more dynamically to wider market forces. In one sense this would remove the unintended consequence as no outcome is planned, and therefore every possible outcome is intended.
Slums and informal settlements
Informal Settlements, Jeddah
The urban phenomena of slums allow some parallels to be drawn, although rather than being intentionally de-regulated these areas tend to be extra-legal and unplanned.
Generally wider economic and social conditions have created pressure that has lead to rapid urban growth that the city cannot keep pace with. Typically the results are pockets of informal settlements, which are often in the left over parts of a city – these could be the edges, parts of unstable terrain, next to major polluting infrastructure, or illegally occupied pieces of land.
There are many negative characteristics in slums to address and to avoid repeating. Many lack basic utilities, access to services, may be structurally unsound, or inaccessible to fire vehicles. All of these are obviously high risk to health in the short-term. Because these areas are inaccessible to municipal services, including security or police, they can make good locations for evading the law, and can also be controlled by gangs.
However, slums also provide some intersting characteristics to learn from. Often they are constructed building by building by the inhabitants for the inhabitants. This means that the scale of the slum and its network of spaces is much more human-scaled than tends to occur in the “planned” parts of a city (page 24). Out of necessity slums also tend to be higher density and mixed use, which consequently makes them much more walkable.
Within the slum, economic activities develop organically where there is a local demand. Furthermore, the spatial structuring of a slum – where typically many buildings each have direct access to the network of paths or streets they are located in – provides opportunity for economic and social interaction with potentially everyone in the slum, and people who may be passing through. For example a house could be used for small scale production of goods which can be sold outside the front door. Spatial accessibility analysis of slums and informal settlements around the world repeatedly finds relationships between the distribution of economic uses and the spatial hierarchy of the area.
In projects where slum dwellers have been rehoused in flats, contained in taller, higher density buildings accessed by a single stairway, this micro-scale economic activity has been seen to suffer. As people are rehoused, access to the street network is lost, and the only people passing by each front door are the other residents of that floor, unfortunately this is not enough potential customers.
Finally, one of the defining characteristics is that the slum may have a clear local structure (spatially, economically and socially), but that this is almost entirely segregated from the wider city. It is arguable that this is not only the problem of slums, but also the mechanism that allows them to exist and develop in the way they do.
Slums provide an interesting comparison in terms of how an urban fabric develops when allowed to according to its own self-organising rules which provide opportunities to learn from. To be clear though, the wider conditions do not form a suitable model for repeatable planned growth: the more able residents make the most of the opportunity they have for small scale economic activity, the less able lack the support of the state to provide a minimum standard of living, do not have free access to social infrastructure, often lack access to utilities and drinking water, and are at risk of being exploited by unregulated landlords, employers or security servcies.
While the discussion around regulation has a focus on the short-term priorities of delivery, there is a fundamental question as to what is being delivered in terms of long-term outcome for residents. It is clear from the example of slums that some level of regulation is required.
Again, there remain questions about how deregulation would impact on the wider society, and what happens to those with little to no choice about where they live, or how they might improve their circumstances. It seems that if the aim of de-regulation is to truly offer freedom, it relies on the provision of a minimum level of access to infrastructure, utilities and services (water, energy, education, healthcare, security) to allow everyone to begin from the same starting point and to at least provide for basic human needs.
Planning, and Masterplanning over the twentieth century is arguably riddled with more failures than successes. As with all other parts to this discussion, there are many elements to unpack, and in a separate post I set out some points around the differences between vision and reality, and this highlighted some themes. One is the tendency to see masterplans as big pieces of architecture and to over-design proposals. This means that designs are not flexible enough to change to the wider context of the complex system, and perhaps a better parallel could be provided by landscape architecture where conditions are set in place at the beginning, and what emerges develops and changes over time.
Where city growth has been successful (Barcelona, New York), it has been accompanied by a minimal framework that allows the actions of many individuals to be coordinated into a whole. It has to be pointed out that these models took place in a different economic, social and development context, where city making happened less often at the scale of masterplan and more at the scale of the building or urban block. More recent rapid growth in places such as Dubai and Abu Dhabi may have been succesful in terms or securing investment and building quickly, however the urban characteristics of these cities do not deliver the same outcomes as Barcelona or Manhatten.
Cities still need to be planned to provide equitable access to services, however this points towards a slightly different approach than has been applied over the last hundred years: Cities need less masterplans across medium scale areas (that define detailed urban characteristics to secure a small number of large investments), and more frameworks that cover large areas (but coordinate many smaller investments, deliver utilities and services), and allow flexibility (especialy for land uses and density) within this.
This approach proposes to design the fewest set of fundamental spatial components based on providing a framework for individuals or groups to acquire land and develop it within some limits (there is also a whole set of legal, financial, components to consider). What might a spatial framework that does this look like?
As a starting point the core components can be split in to voids and solids. The voids carry networks: Streets, Infrastructure, Utilities. The solids carry the physical form: Urban Blocks, Plots, Buildings.
These two components could be described very simply, showing only street centrelines and ownership boundaries.
Through the work of Bill Hillier it can be shown how fundamental the spatial network is to the function of the city. It can be argued that space should be seen as core infrastructure, it is the first thing to be defined and something which is very difficult to change once it is in place.
One of the reasons the spatial network is so difficult to change is that it is often one of the two components that define land ownership (other land being the remaining component). Once ownership is defined it is very difficult to change and there are many examples where even though a city has been demolished, the pattern of ownership often remains intact (great fire of London, 1666).
Therefore, the physical pattern of ownership, essentially plot boundaries, is also one of the fundamental components to define early on.
To retain some control over the outcome of development, and to provide instructions to developers, investors, engineers and designers a set of spatial development rules is also required. These should also respond to the process of city making and change. Some types of land use should not be controlled too strongly, but other elements that affect the impact on the city itself such as the interface between public and private (shaped by density and particularly population per street length), or energy demand/waste creation should.
These are initial thoughts on what a spatial framework might look like to respond to the dynamic context in which cities exist today, and to avoid some of the mistakes of the past. Defining the core components to be both minimal and flexible requires a rigorous, analytic process that relates to the way cities actually work. Although the output of this may look simple, the process behind it is likely to be complex – Deceptive Simplicity.
This will be developed further in a future post.
Viele map of Manhatten, 1865, showing streets, blocks and sewers.
* Ebeneezer Howard
** Solly Angel
*** Solly Angel
**** The Economist