Is Urban Design Evidence-Based?

Evidence-based plans. That is the call these days. An interesting issue is how urban design gets tangled up in this call for "evidence” and comes out the other end not very well off when in fact it is evidence-based.

The Independent Hearings Panel that looked at the Auckland Unitary Plan took up the call on evidence-based plans, and good on them. In their overview report they state (1):

“constraints on choices should be based on evidentially-validated thresholds and not on the consent authority’s preferences”.

To make the point clear they repeat it again a bit later on (2) :

“The reasons for objectives, policies and rules must be based on objective evidence rather than anecdotes or subjective considerations”.

But what is objective and what is subjective? One of the curious aspects of their decision relates to urban design and its place in resource management. You get the feeling that the Panel don’t like urban design. For example (3):

Good design is based on principles rather than rules. Mere reference to good design or the listing of preferred design principles is ill-suited to a regulatory framework which imposes binary ‘grant/decline’ outcomes. Discretionary decision-making must be exercised on the basis of relevant and clear objectives, policies and assessment criteria rather than on subjective preferences.

The Panel are not the only ones to hold this view. The Productivity Commission in their draft report on urban planning said something similar (4):

The role and skillset of urban planners needs to be more tightly defined. A more tightly defined role for urban planners would require some elements of the planning profession (notably urban designers and those promoting New Urbanist ideals) to develop:

• a greater understanding of the scope of influence of the planning profession;
• a clearer focus on the evidential basis for decisions; and
• a greater understanding of the responsibilities that come with the use of the coercive powers of the state.

What I find odd about these comments is that my understanding of urban design is that it is grounded in empirical observations of town and cities and how people interact with the spaces and places created. It is far more grounded in observation and reality (evidence if you wish) than much discourse about what is and isn’t good urban planning. The whole debate around zoning, land supply and housing affordability is driven more by theories about what should happen than evidence about what is happening, for example.

The empirical nature of urban design is what attracted me to the topic. You only need to look at the classic texts on urban design like the Death and Life of Great American Cities, Responsive Environments and the works of Jan Gehl to see how important observation is to the basic building blocks of urban design, while much urban planning is normative.

Urban design is grounded in people’s behaviour when in different urban environments – why do some city environments attract people and activity, while others appear to repel people and activity?  It is clear to me that people are very sensitive to the urban environment and small physical changes can lead to big changes in behaviour. This should not be taken as environmental determinism; rather it is an acknowledgement that we live in a complex world where people and businesses have options and choices, and those choices get shaped by the places around them. As Winston Churchill said - "man makes the town, then the town makes the man".

Urban design identifies and creates conditions that help to make places safer, more inclusive and more user-friendly and therefore successful in economic, social and environmental terms, over time. In so doing, it recognises that there are many different user groups that need to be considered, and that their needs and wants do not completely overlap. So for example in the city centre there are workers, business visitors, shoppers, local and out-of-town tourists, residents, educational users, recreational users (walkers, joggers, cyclists), as well as general visitors. Urban design therefore has a strong element of equity running through it - places that enable all people to use them. From equity comes efficiency.

In urban efficiency terms, good urban design assists with the generation of positive externalities that arise when people and businesses are congregated together (agglomeration benefits). It also helps to avoid negative externalities - in a dense urban environment, a poorly designed building that does not relate to adjacent buildings or public spaces can create a deadening effect on these neighbouring places and buildings, fostering crime and reducing amenity, for example. This is a negative cost on others that the poorly designed building does not carry. Urban design address these externalities by applying a design-based approach, rather than rigid standards - surely a good thing.

I often wonder if the dislike of urban design arises from:

1. observations of built environment outcomes suggests that individual actions in relation to how a site is developed (particularly the public-private interface) don’t necessarily add up to a wider benefit - contrary to the cornerstone of economic orthodoxy that pursuit of individual welfare adds up to community welfare, so long as environmental externalities are addressed;
2. You could say that ‘equity’ of access to and use of urban environments is as important to urban design as urban efficiency, so again its swimming against the tide;
3. Urban environments and their inhabitants are incredibly sensitive to small changes. Sometimes, micro management is needed. But micro management is not the flavour of the month.  

Getting back to urban design, I accept that it can be its own worst enemy sometimes. There is no universally accepted definition of urban design, and as a result urban design evidence can often be wide ranging and not comparable. Principles rather than standards and rules are used due to the complexity of the urban environment and our lack of the precise understanding as to the myriad of interactions involved.

Urban design can therefore be perceived to be “subjective”. But that is a easy stone to throw at urban design if you don't like the message.

Often the only recourse to objectivity is to compare and contrast different urban environments; that is to compare the proposed urban environment with an existing environment with similar qualities and to see if the claimed benefits and costs (positive and adverse effects)  are the same or different. This is, of course, not without difficulty, because of the different contexts involved. Principles need to be applied to a place in a considered way.

In terms of the degree of prescription involved in urban design, this flows on from the above point about small changes having ramifications that flow through an urban area (in complex, interconnected systems, small changes can have amplified effects). Cities are complex systems; to manage complex systems, sometimes a few simple rules are needed, in other cases detail is the deciding factor. When you are in a car at 80km per hour, details of the urban environment don't really matter and a few simple rules probably work OK. When you are at the scale of a person walking down a street at 5km per hour detail matters; detail is everything.

Until we are in a position to fully understand the links between the built environment, human behaviour and wider social, economic and environmental outcomes then there will remain a degree of judgement in urban design as to what may or may not make a successful area or precinct. But that doesn't mean we should down play the basic messages of urban design and their empirical foundations.

Footnotes:

1: Page 36, IHP Panel report to AC Overview of recommendations 2016-07-22

2: Page 37, IHP Overview

3: Page 37, IHP Overview
4: Page 328, Productivity Commission Draft Report: Better urban planning