How do you Design an Evolving City? Pt. II
Project CONDENCITY: Uncovering urbanisms evolutionary potential
Part I of this series makes the case for the importance of our cities evolutionary capacity and introduces the concept of condensity, which you can read here. Part II looks at how condensity might be achieved through a somewhat unconventional master planning framework. This speculation requires a site, for which Sandridge, a new suburb in Melbourne, was chosen. Sandridge was chosen first and foremost, as it is in the city in which I live, the one I know best, and where I completed my Masters of Architecture for which this work was undertaken. Secondly, Sandridge is one of five new suburbs that make up an enormous urban renewal project in the existing industrial area of Fisherman’s Bend, which has been rezoned by the state government for residential and commercial use. This allows us the ability to assess the Victorian government’s business-as-usual framework, speculate on its outcomes, and propose an alternative as a point of comparison.
Fisherman’s Bend Framework
Lets look at the Vic Gov’s proposed framework for the future development of Sandridge. It includes a set of planning rules and guidelines captured in a Design and Development Overlay (DDO32), in addition to a new spatial framework, which will involve constructing new streets, laneways and public spaces, primarily to break down the industrial scale lots. The objective of the overlay is “to create a thriving urban renewal area that is a leading example for design excellence, environmental sustainability, liveability, connectivity, diversity and innovation.” This, in addition to built form that protects sunlight penetration to public open spaces, and a precinct that supports “significant commercial buildings.” Most of the rules are typical of Melbourne planning involving zoning, setbacks and building heights, although some are new to the city such as stipulated dwelling density ratios and minimum family sized apartments. Diagrams taken from the DDO showing some of these rules and spatial carvings are shown below. These rules do not deviate from the standard Melburnian podium/tower typology, with the desire to create activated “street walls” that sit hard on the boundary, with a setback tower above.
What is not clear in this DDO is to what extent the enormous industrial lots will be divided up. The new streets and laneways do some work to achieve this, however when overlaid with the existing property boundaries, one can still expect large lots of, on average, around 5000m². This is assuming that the current land owners do not subdivide to sell, which they may well do, if the market prefers it. However it is also not difficult to imagine developer groups buying up one or multiple properties as they are. The gif below illustrates the property titles that are likely to result in the renewed precinct, and then projects their allowable built form based on the DDO rules. Whilst at first glance, these building blocks may appear to be at an expected city scale, it is important to give context to their size, keeping in mind that the Fisherman’s Bend Framework (FBF) aims for Sandridge to have a population of 27200.
City Superimposition
To that end, and to begin to understand what an alternative framework might look like, the following images show 9 different cities superimposed onto Sandridge, along with the population size that it would support based on the extracted city region’s population density. As can be seen, these cities all differ considerably in density and character; in their lot sizes, building heights and street widths. Melbourne CBD, perhaps unsurprisingly, appears most similar to the FBF projection, though with only around two-thirds of the target population. Other cities such as Barcelona and New York show surprising population density by comparison. Las Vegas, on the other hand, fits in almost too well with the industrial surroundings.
The six densest cities — with the most exemplary urban conditions in my view — were further unpacked in the diagram below, in an attempt to identify their defining characteristics, and to provide a formal and statistical comparison. A block of each of these cities is shown side by side to gain a sense of scale and an understanding into the attributes of their typical lot sizes and building envelopes. What is most noticeable about these blocks, and perhaps the most important take-away of this study, is the average size of their lots, the largest being Rome with 1070m², a fifth of the size of the FBF proposal, and the smallest being Tokyo with 104m², a fiftieth of the size. Smaller lots means more lots, an urban attribute that will be critical in formulating an alternative framework for condensity. To reiterate from part I: “what will enable a city to evolve is its capacity to search the solution space of multi-dimensional urban problems, via broad and high-volume testing”.
Planning Rules
In addition to a morphological study of cities, a study of their rules and those of others has proven foundational to this project. The books Grand Urban Rules, The Grand Projet, and Super Legal Buildings were three of several vital resources for capturing a broad survey of the planning rules and strategies used by cities across the world. Whilst I will not detail their contents, suffice it to say that they undoubtedly informed the rule set for this project, and enabled a point of comparison for Victorian planning rules and more specifically those of DDO32.
Disruptive Forces
This is a side note relating to an observation that is not touched on in part I but is crucial to the proposed masterplan and a city’s evolutionary capacity (which is lacking in the FBF). What I am referring to is the presence of an agency to perturb or disrupt the formal fabric of the city. For example, the conditioned pedestrian walkways and building-puncturing highways of Hong Kong, and buildings that conjoin two lots on opposite sides of the street in Barcelona, would not be supported by standard planning practices and as such, are evidence of the presence of a disruptive agency in these cities. It will be an important part of the Condencity masterplan to capture the freedom to innovate and at the same time the responsibility to make a positive contribution to the urban network.
The Condencity Masterplan
Similar to the FBF, the proposed masterplan consists of two parts, a spatial framework and a set of rules. The remainder of part II shall be an explanation of each element, and the principles that underpin them.
First, the spatial framework. There are a number of decisions that are not directly related to condensity, but are nonetheless important urban considerations. I will step through the decisions here but will not give a detailed explanation for each as the article would simply be too long (and probably bore the reader). The first was to determine what, if any, of the existing site elements (streets, trees buildings etc.) should be preserved. It was decided in this case to preserve a handful of existing industrial buildings which were selected based on, firstly, architectural merit, and secondly, forming an even distribution of industrial sized lots across the suburb. It was also decided to preserve all of the street trees, as firstly, this helps to maintain the sites living ecology, and secondly, their preservation maintains an imprint of the previous condition. This idea was inspired by an observation on a trip I took to Christchurch, of the trees that remain on the site of suburban areas rezoned due to high earthquake risk (see image below).
The next key decision was to overlay a new grid of streets onto the site to facilitate the creation of smaller lots. The grid is aligned true north for ease of orientation, but perhaps more importantly because the grid at this angle collides with the existing buildings and lines of street trees, diversifying lot sizes and creating the opportunity for transverse axes. The lot conditions are further diversified via random consolidation to make some twice the width and by having a three-tiered hierarchy of streets, where the smallest are only 5m wide, and the largest are 20m wide. The gif and grid diagram below give a visual explanation for the steps described above.
Now onto the rules. The rules are divided into the rights of the individual, rules of the street, of the block and of the lot. I’ll run through the important points of each of these rule sets, and the principles that underpin them, and then in Part III we’ll see how these play out in a test site.
There are five principles that underpin these rules, the first two are required for healthy citizens, and the remaining three are based on condensity:
- Access to sunlight
- Access to open space
- Small lots enable wider ownership and participation in the creation of the built environment
- Diversity of building use is fundamental to neighbourhood amenity and the key to decentralisation
- Freedom of development should be proportional to responsibility in order to direct positive innovations and evolution.
The principles for a healthy citizen are captured in the rights of the individual, with a right to sunlight and open space and tree conservation. The rules of the street set up varying widths, and varying street conditions, aimed at being tighter where possible. The rules of the block stipulate the composition of lot types, the requirement of public open space, and importantly, the prohibition of the consolidation of multiple lots. Multiple lots may be owned by the same entity, however each lot must be self sufficient, and self contained. The rules of the lot capture the principles of diversity of building use and freedom vs responsibility.
There are three different lot types that an owner may choose to follow when developing a building, which provide varying degrees of freedom, with a proportional level of responsibility; they are the Accountant’s lot, the Entrepreneur’s Lot and the Dissident’s Lot. I will now explain the rules behind each of them, by showing how a given regular and irregular lot might be developed under each type. I should also explain at this point that it is these rules that are the primary drivers of form in this project, and their current state is the result of a number of iterations which aim to find a balance between numerous embedded trade-offs.
The Accountant’s lot is named for its predictable outcome, its low risk and its low responsibility. The building’s maximum height is 25m with setbacks on the side and rear boundaries of 45 degrees, starting at a height of 12.5m above ground level. The setbacks to street elevations are taken from the opposite side of the street at an angle of 45 degrees, meaning that the wider the street, the lesser the setback. An accountant’s lot need only incorporate a minimum of two uses, with one primary use and a streetscape offering. The maximum floor area ratio is 6:1, and there are no additional overshadowing controls.
The rules for the Entrepreneur’s lot and the Dissident’s lot start out the same, and so will be explained in parallel. The first rule is one of overshadowing, stipulating that a building’s shadow must allow a minimum of 5hrs direct sunlight for at least half the area of the neighbouring lot on the spring equinox. This rule leaves the form of the building open ended as we’ll see. So in one example (shown below), the built form may be cut at an angle to allow the sunlight to pass above, in which case the maximum allowable envelope will be as shown. If the owner was to continue along the Entrepreneur’s lot path, they would be required to accommodate a minimum of three uses, with a floor area ratio of 8:1, this FAR can be increased for each additional use provided, thus an increase in yield is also an increase in diversity of use. The Entrepreneur’s lot must also comply with the rules of the block, meaning that it must contribute to the block’s minimum public open space requirement as shown.
If instead the developer was to follow the Dissident’s lot path, they would be required to accommodate a minimum of four uses, with an allowable increase in floor area for each additional use provided. It must also comply with the rules of the block, providing the required public open space, however where it differs from the Entrepreneur’s lot is its innovation offset clause. A development may extend beyond the boundaries of the lot under the condition that it can be demonstrated to provide exceptional benefit to the occupants of the land onto or over which it extends. Where the land is public, the population is considered to be the general public. This clause is intended to incentivise innovation with the reward of an increase in yield.
In another example shown below, overshadowing could be reduced by pushing the building envelope to one side as shown. In this situation the building is not constrained vertically, and so following the Entrepreneur’s lot, could capitalise on additional height through rules such as development rights transfer and new use offset. The Dissident’s lot similarly will allow for a taller building through the new use offset.
With the rules and spatial framework of this masterplan now established, that concludes part II of this series. As mentioned, part III will zoom in on a chosen zone to speculate on what could be the urban and architectural outcomes of this masterplan.
