What is the deeper concept of mixed use and how can it be achieved?

8/14/2019 What is the deeper concept of mixed use and how can it be achieved?

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What is the deeper concept

of mixed use and how canit be achieved?

Tim Wright

6058318


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Contents

4 Introduction

4 Historical Context

5 The Industrial Revolution

7 Post Industrial Revolution

8 Assumed benefits of Mixed Use

9 What is Mixed Use?

9 Problems with the simple concept of Mixed Use

10 What is the deeper meaning of the concept of Mixed Use

10 Design elements that can improve diversity

19 Summary of design elements that can affect diversity


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20 Context and the degree of intervention

21 Changes over time

22 Conclusion

22 Recommendations: The role of planners and urban designers

25 References


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Introduction

The idea of mixed use has become a popular term and is seen as one of the ways in which to achieve

better urban outcomes for our cities.

Despite the popularity of the mixed use concept in modern times, there seems to be debate as to itsdefinition and its ability to deliver what it promises. Planners need to delve deeper into the concept

to understand its deeper intensions.

The term diversity is used in this paper to describe this deeper concept. It includes mixed use as one

of many elements that make up diversity instead of it being the overarching concept itself.

Historical Context

From the start of civilisation the mixing of activities has occurred. The places to live, work and playwere tightly intermingled as walking was the primary and in a lot of cases the only means of

transport. The distance people were able to move was limited to carry out necessary daily functions,

(Urban Land Institute, 2003). This can be seen in the below figure 1 of the compact old-town of

Avignon in France, whereby the town was limited by the distance people were functionally able to

move.

Figure 1: AvignonFrance (Gentin, 2009, pg 22)

This limited the overall size of the city and importantly the space available for individual functions.

For example a shop or residence was limited in size to ensure efficiencies in space. If individual

functions were too large, then the city would expand and walking distances as a result would grow.

This would dilute the efficiency of the entire city. A significant proportion of residents lived and work

within the same building, selling items from the same building also, (Herndon, 2011).

Prior to the early 19th

century, a lot of cities had the following similarities:


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People walked as the main means of transport; Uses and activities were mixed within buildings and/or within cities; Population densities were high, increasing towards the city centres; and There was a clear distinction between urban and rural areas, (Herndon, 2011).

The Industrial Revolution

In a lot of countries the onset of the industrial revolution brought about key societal changes that

would prove to have a significant effect on the way activities and uses were organised and

segregated within urban areas. These key changes were:

Industrialisation

The process of industrialisation changed economies from being agriculturally based to one based on

the manufacturing of goods and services.

Technological advances dramatically increased the productivity of individual farm labourers, and

mechanization, along with the division of labour, created industrial synergies in the mass production

of goods.(Herndon, 2011, pg 4).

This had significant implications for the urban fabric.

Small artisan shops were replaced by factories that could mass produce products cheaper. Buildings used for live/work arrangements were now used to house the great influx of

required factory workers pouring into urban areas from rural areas.

The continued evolution and rise of industrial capitalism created a need for large amounts ofclustered office space.

Thus, for the first time, functions that were previously integrated into single structures were being

compartmentalized into individual buildings and districts. (Herndon, 2011, pg 4).

Urbanisation

As urban populations rose due to the process of industrialisation mentioned previously, cities grew

both horizontally and vertically. The many farms on the periphery of urban areas, once used to feed

the cities inhabitants, become less important due to the increase in agricultural output of a few

farms. Farming land was urbanised and accounted for horizontal growth. Simultaneous advances in

building construction, such as steel and elevators, enabled buildings to increase in height

significantly, accounting for vertical growth.

The resulting increase in population density could not be handled adequately by a lot of these

industrial areas and they become known for poor sanitation, congestion, filth and disease. This was

exuberated by polluting factories scattered around cities.


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As a consequence, perceptions of urban areas deteriorated and the traditional principles of urban

form, such as high densities and mixed uses, developed negative connotations. (Herndon, 2011, pg

5).

Transportation

The poor inner-city conditions meant that people wanted to escape to the periphery of cities. This

desire was facilitated by advances in transport technology. Initially trams had a significant effect on

how cities grew horizontally; increasing the distance commuters could travel from place to place.

However much more fundamentally the rise of the private automobile really changed the way

people moved and allowed great expansions in the horizontal fabric of cities.

automobiles shattered constraints that the human stride had placed on the urban fabric and

fundamentally altered the horizontal scale of the built environment. (Herndon, 2011, pg 5).

Zoning

The problems associated with industrial cities lead to the introduction of zoning regulations amongst

many cities in the developed world. The purpose of the regulations was to separate those land uses

that were or were regarded as being incompatible. Residential areas were segregated from the

intensity of commercial areas and the noise and pollution of industrial areas, as shown in figure 2

below.

Figure 2: Living conditions within industrial cities (webs.bcp.org, 2013)
http://www.google.co.nz/url?sa=i&rct=j&q=housing%20industrial%20revolution&source=images&cd=&cad=rja&docid=Eq9r_Zci98IYsM&tbnid=HcwSJOrT5lACaM:&ved=0CAUQjRw&url=http://webs.bcp.org/sites/vcleary/ModernWorldHistoryTextbook/IndustrialRevolution/IREffects.html&ei=gVwUUsGaO4WfkAX6x4HAAw&psig=AFQjCNFxqtobLOTq0W1tP4E8sUfxhbg9LA&ust=1377152496401935


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Ever worsening traffic congestion and air quality caused by intensive automobile use; Costly requirements to expand roads, sewers, water systems, and other infrastructures

outward, rather than utilize and upgrade the networks that are already in place;

Isolated neighbourhoods and communities which lack vibrancy and a sense of place; and Inadequate public transportation and a lack of other public amenities. (Downs, as cited in

Herndon, 2011, pg 22).

A return back to some of the elements of urban conditions pre the industrial revolution is widely

regarded by new urbanism as a cure to tackle these detrimental consequences. Mixing uses is

viewed as one fundamental element to achieving this.

Assumed benefits of Mixed Use

While there is little argument that combining different uses will be a more successful strategy than

segregating uses, it is a simplistic view to imagine that simply combining two or more uses within a

building or spatial area will produce all the benefits associated with mixed use development, such as:

Convenient access to facilities;

Minimizing travel-to-work congestion;

Opportunities for social interaction;

Socially diverse communities;

Safety, eyes on the street;

Energy efficiency and efficient use of space;

More choice of lifestyle, location and building type;

Urban vitality and street life; and

Viability of urban facilities and support for small business. Llewelyn-Davies, as cited in

Carmona, 2010, pg 221).

The mere fact that a development contains a mixture of uses is no guarantee of lasting quality,success or acceptability. There are many other conditions that need to be satisfied. (The Royal

Institute of Chartered Surveyors, 1996, pg v).

There are, however, many examples of developments that have been marketed under the banner of

mixed use yet fall far short of delivering the benefits discussed above. So what actually is mixed

use? And how can it help to generate all the benefits that have been associated with the term?


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What is Mixed Use?

In simple terms mixed use implies different uses mixed together in a spatial setting. This is what

most is commonly associated with the term and most in the industry would perceive this as being

generally accepted.

Douglas Wheeler Associates (2009) defines it in similar terms below.

Mixed use is generally loosely defined but can encompass single developments with two or more

revenue producing uses (vertical mixed use) and mixed use neighbourhoods with significant

physical and functional integration including real physical connections between uses within a five

minute walk (horizontal mixed use). (Douglas Wheeler Associates, 2009, pg 1).

While this is a definition produced in Scotland, the broad meaning of combining differing land uses

within a spatial area is generally translated across many parts of the world.

Problems with the simple concept of Mixed Use

While on the surface the definition of mixed use seems simple and universal, once the surface is

scratched the definition produces more questions than answers, as pointed out by (Herndon, 2011).

Does the word mixed imply a certain level of integration or degree of compatibility among

uses?

Does the manner in which the different uses are combined, i.e. vertically in a single building

or horizontally in multiple buildings on a single site, matter?

Does the geographic scale of a project matter?

Is a certain intensity of uses required for a project to be considered mixed use? (Herndon,

2011, pg 10).

All definitions include the basic theme of incorporating more than one use as being the corner-stone

of the definition, yet various definitions also include other elements. Therefore the concept of mixed

use becomes ambiguous and because no clear definition can be agreed upon the concept is open to

misinterpretation, which leads to uncertainty, which leads to misunderstanding, which leads to

miscommunication, (Coupland, 2009).

A problem with the term as pointed out by The Royal Institute of Chartered Surveyors (1998), is that

it means different things to different people especially in the development industry. The fact that it

is regarded as different from single use development is often deemed sufficient in terms of

definition and meaning.

Furthermore because the concept is not clearly defined the term mixed use is becoming no more

than a marketing tool for developers (Rowley, 2010), implying that any development with two or

more uses is a successful mixed use development encompassing new urbanist qualities.


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Schemes which offer few, if any, of the benefits of traditional mixed-use areas are, nevertheless,

described as mixed-use developments. This debases the concept and risks reducing support for the

idea. The term is used as a marketing slogan by some people and the concept is seen as a panacea

by others. (Rowley, as cited in The Royal Institute of Chartered Surveyors, 1998, pg 5).

The above quote provided a distinction between the definition and the concept of mixed-use.

Perhaps arriving at a precise definition is meaningless. It seems more important to examine and

come to terms with the deeper meaning behind the concept rather than defining the term.

Planners typically have a larger frame of reference, but seem to care less about the details of the

definition and more about the intent behind the concept.(Herndon, 2011, pg 11).

What is the deeper meaning of the concept of Mixed Use

Perhaps the problem with the term mixed use is that the words are too easy to define. The word

mixed implies a difference and a difference only needs two items, one to be different from the

other. The word use in planning circles refers to landuse. Therefore simply put and understood, the

term mixed use arguably refers to two or more different landuses. It is difficult to argue with this

meaning and this may be why the deeper meaning has been glossed over and lost.

A less tangible and more abstract term may be more fitting to describe a concept as deep as this.

The term diversity seems a better fit to acknowledge such a deep concept. Diversity is used by

such theorists as Jacobs. The beauty of the term is that it cannot be defined in a black and white

sense as opposed to mixed use. It is grey. It is also, like the term sustainability a measure, it is

almost impossible to achieve total diversity, like it is to achieve total sustainability. However it is

possible to achieve a greater level of diversity relative to what presently exists.

In simple terms the deeper concept of mixed use or diversity, which ever term you use, is about

difference and variety within a spatial area. It does not limit itself to landuse, as the term mixed

use suggests but covers all aspects of the urban environment.

Design elements that can improve diversity

Attempting to clarify all the elements that make up diversity in one go will serve to lessen its effect.Therefore the following is a breakdown of the various elements that can improve diversity.

Density

Jacobs (1961) states the need for density as one of her essential ingredients to create diversity. She

states that:

The district must have a sufficient dense concentration of people for whatever purpose they may

be there. (Jacobs, 1961, pg 162).


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The connection between diversity and density can be observed throughout the world, the greater

the concentration of people the more diverse the activity that takes place in a given area. In

economic terms the more thinly spread people are the less viable activities become because the

population is not there to support the activity. Therefore only limited access to services will be

available. For example if a place contains 100 people and 20 of these people want an Indian

restaurant in the local shopping centre, it would not be viable economically. However if the place

contained 1000 people and 200 people want the same facility, then it may become viable. When

discussing low density areas, Denton points out:

The only goods and cultural activities available will be those that the majority requires, (Denton,

as cited in Jacobs, 1961, pg 213).

As densities increase the viability and demand for a greater range of activities and services also

increases. This is not only due to a greater volume of population, but also with a greater

concentration in people comes a greater demand for variety in tastes and needs. This is because

humans are diverse, everyone is different and our needs and wants are different too, this does not

only relate to consumer products, but also other things such as recreation, work and living

arrangements.

In summery the higher the density, the more potential for diversity a place will have.

Permeability

Permeability refers to the amount of choice there is to take alternative routes within an area. If a

place has many alternative routes it can be said to have a high level of permeability, alternatively if

there is limited choice in routes a place can be said to have a low level of permeability or it is

impermeable, (Rowley, 2010), as shown in figure 4 below.

Jacobs (1961) also comments on the need for permeability as one of her essential ingredients to

create diversity. She states that:

Most blocks must beshort; that is, streets and opportunities to turn corners must be frequent.

(Jacobs, 1961, pg 162).

Figure 4: Permeable vs impermeable movement network (Gentin, 2009, pg 12).


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Why does this act to increase diversity? The permeability of streets within an area effects how

streets are used and in turn the activity on the streets and within the buildings along the streets. In

figure 5 below the diagram to the left shows a street block with a relatively low level of permeability.

Residents situated on the long streets are consigned to travel in an east-west direction to access the

main north-south running street. Because all the other east-west streets follow the same pattern a

standardisation in use of the streets evolves. A distinct pattern of commerce evolves within the

north-south running street, while because of a limited amount of traffic (only that which travels on

that particular street) moves along each long east-west street; a standard pattern of residential use

evolves. Therefore this lack of permeability has acted to segregate the viability of activity; funnelling

a concentration of activity to the north-south running street and at the same time strangling activity

in the east-west running streets, (Jacobs, 1961).

Figure 5: Permeability effects street use, (damienwoolliscroft.tumblr.com, 2013, adapted from Jacobs,

1961).

Now consider the diagram to the right in the same figure. A mid-block street now allows people to

move in a variety of different ways around an area. This exposes parts of the area, which were not

exposed before to differing amounts of traffic. This in turn opens up the area to different economic

and activity potentials. The corners in particular are now prime areas for commerce uses, where

before they would not be viable for such an activity. Furthermore, the main north-south runningstreet may now have a slightly less intensive character and may suit other activities, which attract a

less intensive environment.

In summery the higher the permeability, the more potential for diversity a place will have.

Robustness of built form

Related to how built form changes over time is the concept of building robustness. If built form

exhibits a high level of robustness then it can adapt to accommodate a wide range of different usesand activities easily. The ease in which a building can be adapted to accommodate a different use is


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important it affects its economic viability. It a building is difficult to adapt then the price for

renovation usually increases, making change less viable. In some cases a building will be so un-

robust, or purpose built, that accommodating different uses is impossible.

Carmona (2010) lists the main attributes that can affect the adaptability of a building to be robust as

being the cross-sectional depth, access, room shape and size. When the design of built form

considers these attributes there is greater ease and more likelihood of changes over time.

Building robustness can also refer to how easily a building can be extended. Often this relates to

horizontal extensions to the external face of a building, however this can also relate to vertical

extensions. In areas that are presently not suitable for high densities or building heights, but could

possibly accommodate them in the future, architects and builders could consider ways of

construction that could allow for vertical extensions in the future.

In summery the higher the robustness of built form, the more potential for diversity a place will

have.

Balanced building setbacks

The way in which built form is positioned within a block or site effects its perception of being private

or public. If built form is setback only slightly from the public street, then its perception is more

public then if it were setback further from the public realm, which can be perceived as being

privatised insinuating unauthorized access, (Lewis, 2005).

Buildings that are setback only slightly can be said to exhibit a public front. This is then often coupledwith a private back, as demonstrated in a simple perimeter block configuration, as shown in Figure 6.

Figure 6: Buildings only setback slightly from the street, forming a perimeter block, (Carmona. M, et al,

2010).


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However buildings that are setback significantly are often only perceived with private space

surrounding them with little or no interaction between the building and the public realm, as shown

in figure 7 below.

Figure 7: Buildings setback slightly from the street as opposed to being setback greatly from the street,

(Wright, 2013).

In the top diagram private space is created in the front yard area. Often this space will be further

privatised with the use of high solid fences, keeping public interaction out. This form of development

allows little variety in use, usually only suitable for private residential purposes.

How does this relate to diversity? Different uses and activities require different environments to

function well. For example retail uses when located within the public realm, i.e. with a close

relationship and proximity to the street or other public space, function well as do many non-

residential uses and activities. If they were setback far from the street then they might be perceived

as being private and therefore not function as well.

On the other hand residential uses often function better within a private or semi-private realm.

Although with careful design, residential uses can function adequately close to the street as they can

be designed with a public front and a private back.

Figure 8 below shows a more balanced situation between offering a degree of privacy and a degreeof public interaction. This design can suit a range of activities allowing a greater degree of potential

diversity to accommodate the built form, including residential and non-residential uses.

Figure 8: Ground floor condition offering a balance between privacy and public interaction, (Wright, 2013).


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In regard to residential uses they can also be setback or separated vertically from the public realm,

which also allows a form of privacy as shown in the below figure 9.

Figure 9: Vertical separation of uses, (Wright, 2013).

Furthermore when buildings are setback only slightly from the street, more space is often created at

the rear (back), which provides better separation of different uses within a block as the greater

spatial separation will act to buffer any use compatibility issues, as shown in the below figure 10.

Figure 10: Greater separation of backs allows greater diversity of uses within a block, (Carmona, 2010).

In summery the greater number of balanced building setbacks, the more potential for diversity a

place will have.

Attaching buildings

Adjoining built form along a street as opposed to the creation of side setbacks, provides further

clarity between public and private space. When built form is adjoined it creates a wall of active

public perception and frames the public realm (street), it signifies to people moving through the

space that this is the public realm. It also provides a clear barrier between the private spaces, often

to the rear or back of built form. When buildings are separated confusion can arise as to whether the

space is public or private especially when the two neighbouring uses differ, for example a residential

dwelling and a caf. This can affect not only the use of that space, but also the use of the adjoiningspace.


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Furthermore, Lewis (2005) suggests that a perimeter configuration of built form allows greater

flexibility for various building forms to coexist. This is because it allows various forms of buildings to

adjoin each other in a terrace form, which requires little or no regard to the side elevation of a

building. This also removes use and management issues that can arise from the space in between

buildings, increasing the suitability of having a mixture of uses adjoining each other. The common

boundary wall can effectively become a transition point between various uses, whereas if buildings

are detached the spaces in between becomes a visible transition point and requires greater use and

management consideration as shown in figure 11 below.

Figure 11: Attaching buildings removes use and management issues when different uses adjoin

eachother, (Wright, 2013).

In summery the greater number of attached buildings, the more potential for diversity a place willhave.

Streets and the public realm

Once we move beyond the scale of the individual building then streets and the public realm become

involved. Therefore the discussion of diversity needs to include not only what occurs within buildings

or the private realm but what also occurs within the public realm, the streets and areas of open

space.

As The Royal Institute of Chartered Surveyors (1998) explain the diversity of activities which occurs

within streets and public open space areas is not only a product of what occurs within the built form

and blocks that adjoin, but also the design of those streets and public open space areas. How the

public realm is designed and used affects the activities within buildings just as much as how the

activity within buildings affects the adjoining public realm.

For example if a street is very pedestrian friendly by way of its design, by limiting vehicle use or

stopping it all together, yet still has a lot of pedestrian traffic, it will create a viable place for a use

within a building like a caf, as the place created will be economically viable, a good place for people

watching and void of car fumes.


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Different uses and activities benefit differently from different situations, residential uses prefer quiet

areas, some businesses prefer exposure to great vehicle numbers and some cafes prefer a tranquil

setting. Therefore diversity of activities benefits from a broad range of various public realm

characteristics.

In summery the greater variety in public realm design, the more potential for diversity a place will

have.

Age and condition

Jacobs (1961) considered the need for variety in terms of age; condition and quality of built form in

order to accommodate differing economic conditions, which will reflect in different socioeconomic,

cultural and age groups intermingled in an area.

In summery the greater variety in the age and condition of the built form, the more potential for

diversity a place will have.

Grain

Grain refers to the way in which all the components of an area are mixed together, including people,

activities, land uses, buildings and space. Grain is a measurable term whereby a finer grain results in

a finer mix of components, often characterised in historic European towns. A coarser grain results in

a coarser grain of components, often characterised in many western cities, (Rowley, 2010), as shown

in figure 12 below.

Figure 12: Fine vs coarse grain of land-uses (Gentin, 2009, pg 12).

Therefore grain ultimately refers to the proximity in which one component is spatially separated

from another component. For example if a dwelling is situated close to a coffee shop it can be said

to have a fine grain, or if a one bedroom unit is situated close to a three bedroom townhouse it can


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be said to have a fine grain. Alternatively if a three bedroom detached dwelling is separated from a

coffee shop by twenty other three bedroom detached dwellings it can be said to have a coarse grain.

This theory, however, is not only limited to land-uses. It encompasses such things as:

People, meaning demographic mixes, including affluence levels, cultures and age; Activities, meaning recreation, work, living and movement/transporting; Buildings, meaning age, heights and scale etc; and Space, meaning public and private open space and streets.

Therefore the amount and degree of difference in all these components within a certain area can

determine the level of richness in grain an area has.

In summery the finer the grain of components, the more potential for diversity a place will have.

Mixed functions

Jacobs (1961), states that a district requires more than one and preferably more than two primary

functions as a way to increase diversity. This will ensure greater activity within an area throughout

more hours of the day as different functions operate differently, for example residential activity

generally operates during non-working hours, while business activity operates during working hours.

This concept is purposely kept general to account for all the grey in-between areas of activity such as

residents who do not work or people who work from home or business that operate after hours.

Such activities do not fit in with this generalised concept, yet nevertheless add significantly to the

activity generated in a place.

Secondary functions then support and feed off those primary functions. The survival of secondary

functions is often attributed to a healthy mix of primary functions from an economic point of view.

For example a caf/restaurant will be more viable if it can do business throughout more of the day

and on weekends. A general scenario of how this translates may unfold like this: first by feeding an

early morning breakfast crowd made up of people going from or coming to the area for work, then

transitioning to providing lunch for the workers within the area, then transitioning to providing an

evening meal to the residents and some workers in the area. Additionally stay at home parents may

drop in for morning or afternoon tea, (Jacobs, 1961).

Importantly it is considered relevant to add mixed conditions of the same use type. For examplewhen considering a residential use, a variety of differing formats will increase diversity, for example

units that offer different amounts of rooms or sizes of yards, will attract differing groups from

students, families and the elderly.

Another aspect is the difference between the intended and actual use of places and spaces. The

original intended function of different places can become blurred. The original intention of a place

maybe used for not only that function but also others, which were not the original intended

functions of that place. For example cafes are commonly now used for business meetings as well as

serving food and drinks, sidewalks and local parks are used for alfresco dinning and markets as well

as for pedestrian movement and recreation and housing is used for business as well as a place ofresidents.


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Diversity Element More Greater Variety

Density X

Permeability X

Building robustness X

Balanced building setbacks X

Attaching buildings XThe design of streets and public spaces X

The age and condition of built form X

Finer grain of uses and activities X

Types of uses and activities X

Tenure X

Context and the degree of intervention

It is important to recognise that different areas will require different responses or interventions to

increase diversity.

A central city or fringe central area for example may already exhibit some elements that can improve

diversity, such as high densities and good permeability; therefore only minor interventions to

increase diversity will be required. While a suburban area may require larger interventions due to

low densities. Rowley (2010) describes these as four locational settings whereby mixed use settings

are found or may be promoted.

City or town centres comprising the commercial and civic core of towns and cities;

Inner-city areas and on brownland sites comprising derelict, vacant or built-up land needing

regeneration;

Suburban or edge-of-town locations; and

Greenfield locations where planning policy permits. (Rowley, 2010, pg 87).

In terms of intervention, Rowley also states three approaches to maintaining or promoting mixed-

use.

Conservation of established mixed-use settings;

Gradual revitalisation and incremental restructuring of existing parts of towns, including infilldevelopment and reuse, conversion and refurbishment; and

Comprehensive development or redevelopment of larger areas and sites. (Rowley, 2010, pg

87).

Conservation interventions are typically applicable to city or town centres or inner-city areas where

urban conditions are already suitable for fostering diversity, for example with high density, differing

ages and quality of built form, good permeability and an existing array of varied activities.


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Gradual revitalisation and incremental restructuring interventions are typically applicable to inner-

city areas, which display a good range of the urban elements that encourage diversity but could be

better, with the help of some intervention.

Finally comprehensive development or redevelopment interventions are typically applicable to

suburban or greenfield locations which do not have the appropriate conditions to foster diversity.

It is also important to also consider the context of an area in terms of its expectations, as different

areas within a city will have different expectations in terms of design, for example an inner-city

location will expect to have higher densities and taller buildings then a suburban setting. Therefore

the degree of intervention should reflect the degree of change needed relative to the context of the

area. For example if a town centre area is less dense then what is expected it may require gradual

revitalisation and incremental restructuring interventions to increase its performance rather than

conservation interventions. On the other hand, a suburban area may exhibit a relatively high density

in regard to its location, therefore a conservational type intervention maybe applied in terms of

density.

Changes over time

Critics of Jacobss philosophy argue that it is all well and good looking at a section of New York City

as being a diverse place as it already has a high level of density and scale in which diversity will

naturally occur. They argue that new high density developments in a lot of new areas actually

produce less diversity and mixture of uses, for example new office tower blocks in central city

locations, will have a low level of diversity, (Hirt, 2012). Furthermore the areas in a lot of cities that

exhibit the most diversity and mixture of uses are the transitional areas on the edge of the central

city, where densities are much less than the central area. Therefore higher density does not always

lead to higher levels of diversity and they are right for the most part.

What they are missing, however, and this maybe an oversight, a deliberate omission or something

not deeply commented on by Jacobs is the effect of time. As areas and buildings age, the activities

carried out within them multiply, divide, refine and change, i.e. the grain becomes finer. The Royal

Institute of Chartered Surveyors (1996) term this as the life or lease cycle of property.

There is also the life or lease cycle of property. The high costs of new commercial buildings, for

example, usually means that only the most profitable organisations can afford to occupy new

accommodation. This initial pattern gradually evolves; processes of sub-letting, assignment and sub-

division occur, and a richer mix of activities, population and local life styles may develop. Changes of

use may occur within a building or block, and space may be adapted and refurbished to suit the new

circumstances and opportunities which include occupation by less profitable activities. (The Royal

Institute of Chartered Surveyors, 1996, pg 5).

A similar argument could be put forward to other elements that can increase diversity, such as

permeability; weighing up the long-term advantages of whether or not to create a new road over

the short-term disadvantages of losing a few buildings.


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Redevelopment needs to be thought of in terms of priorities and short and long term thinking. A

situation may arise whereby a developer will want to demolish a piece of well establish built form

that has evolved to incorporate a diverse range of activities, yet the scale and density is low

compared to what could potentially be developed. The new development however will initially only

involve only one activity. Therefore there is a conflict in terms of diversity as the short term

consequence of the redevelopment will act to lose diversity, while in the long term as the building

ages diversity will evolve naturally.

Conclusion

The idea of mixed use has become a popular term and is seen as one of the ways in which to achieve

better urban outcomes for our cities.

Despite the popularity of the mixed use concept in modern times, there seems to be debate as to its

definition and its ability to deliver what it promises.

The debate over the definition of the term mixed use and the implied benefits that often do not

translate into reality suggests that a deeper understanding about the route meaning of mixed use is

required.

The term diversity is one such term that could be used to provide a broader meaning to the true

intent behind the concept of mixed use. The various elements discussed in the report show that

diversity encompasses elements of the mixed use concept but goes a lot further.

If we are to create truly mixed diverse urban spaces, then perhaps we need to acquire a deeperunderstanding of the term mixed use or diversity and more importantly how to implement

interventions into the planning system that align with the objectives of the concept.

Recommendations: The role of planners and urban designers

From the research undertaken above, I have formulated what I think could be a useful hierarchical

process for undertaking measures to increase diversity.

The first task, when considering diversity, is to analyse the context and attributes of the study area.Every area will be different and will therefore require a different response. Some areas may already

contain most of the attributes required for diversity to flourish and therefore only need minor

interventions; on the other hand some areas may require deeper interventions.

The context of the areas of the area also needs to be considered at this point as the built form and

design of areas differs depending upon the location, for example an inner city location will likely be

compatible with higher buildings and density then an urban fringe location. It is important at this

point to consider the role and vision of the area in the context of the wider town or city.

Once the context has been established the second task is to consider, what I class as the

fundamental elements of diversity, those elements that are considered vital to providing a platform


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for which other more detailed elements can build upon. These elements could be considered at a

broad strategic level, they are:

Density; and Permeability.

Without a reasonable density a place cannot create a critical mass of people in which to make viable

a range of different uses. Without permeability different areas within a space will not receive the

exposure required for various uses and activities to flourish. Before other elements that can improve

diversity are considered, the implementation to improve these fundamental elements needs to be

undertaken.

Once the above elements have been considered or if in some cases they are already present, more

detailed interventions can be considered, which are:

Building robustness; Building setbacks; Attaching buildings; The design of streets and public spaces; and The age and condition of built form.

Building robustness allows a range of uses to inhabit spaces easily, initially and into the future.

The front setback of buildings plays a significant role in defining the public or private use of the

building. Design detail can be used to ensure a range of uses can be accommodated functionally,

particularly on the ground floor of buildings.

Attaching buildings along a street front, although not vital should be encouraged as it can help to

provide a continuous public realm front and distinguish between public and private space better, it

also helps with the transition of different uses along a street.

Often streets are under-considered by planners, they are left to the domain of engineers. However

they can have a significant impact in the way spaces are used. Introducing variation into the design

of streets and open space areas can produce various different experiences within a space. This

includes such measures as reducing the width of streets, making some one-way or even pedestrian

only and introducing street trees or other various types of paving and articulation. This may lead to

different uses and activities emerging out of these different experiences.

The age and condition of built form can create diversity of use. However it is important to consider

the higher order goal of ensuring densities are as high as possible. If an area is being planned for

redevelopment, whereby new built form would have a significantly higher density then what exists

currently, it would be a mistake to save built form only for the sake of retaining a variety of ages and

conditions. The goal of creating density should come first. Built form should only be preserved were

it has a similar or higher density to that which is being developed. This is not to say built form that

has heritage value should not be preserved, this is another matter altogether. Once a foundation of

density has been established within an area, overtime different buildings will be replaced and

upgraded at different times, and then a mixture of ages and conditions will establish itself.


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Once the above interventions have been carried out a platform will have been created in which the

other elements discussed previously will be able to flourish and evolve naturally without the need

for much if at all any formal intervention, such as:

The grain of uses and activities; The mix of uses and activities; and Various forms of tenure.

While proactive intervention does not need to occur to implement these elements, a review of

policy should be undertaken to ensure that current policy does not impede their natural

development.

The diagram below summarises my recommended hierarchical procedure for measures to increase

diverse.

Context

Analysis of the context and existing attributes of the study area.

Fundamental

Elements

Density; and

Permeability.

Detailed

Interventions

Building robustness;

Building setbacks;

Attaching buildings;

The design of streets and public spaces; and

The age and condition of built form.

Natural

Evolution

The grain of uses and activities;

The mix of uses and activities; and

Various forms of tenure.


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References

Carmona. M, et al, 2010, Public Places Urban Spaces the Dimensions of Urban Design, Oxford:

Architectural Press, UK.

Coupland. A, 1997, Reclaiming the City: Mixed Use Development, E & FN Spon, London, UK.

Gentin. M, 2009, All Mixed Up: A critical analysis of mixed use, Bachelor of Planning, UNSW,

Australia.

Herndon. J, 2011, Mixed-Use Development in Theory and Practice: Learning from Atlantas Mixed

Experiences, Applied Research Paper, USA.

Hirt. S, 2012, The Urban Wisdom of Jane Jacobs, Routledge, New York, USA

Jacobs. J, 1961, Death and Life of Great American Cities, Random House, New York, USA.

Lewis. S, 2005, Front to Back: A Design Agenda for Urban Housing, Architectural press, UK.

Urban Land Institute, 2003, Mixed-Use Development Handbook, 2nd

Edition, Urban Land Institute,

USA.

Rowley. A, 2010, Mixed-use Development: Ambiguous concept, simplistic analysis and wishful

thinking?, Planning Practice and Research.

The Royal Institute of Chartered Surveyors, 1996, Planning Mixed Use Development: Concept and

Realities, The Royal Institute of Chartered Surveyors, UK.

The Royal Institute of Chartered Surveyors, 1998, Planning Mixed Use Development: Issues and

Practice, The Royal Institute of Chartered Surveyors, UK.

Documents

What is the deeper concept of mixed use and how can it be achieved?