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Intense relationships: measuring urban intensity

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Enriching design practice by the mapping of human behaviour patterns could transform urban space

There’s much debate about how to measure density – dwellings per hectare, bedrooms per hectare or people per hectare; including or excluding major highways, parks and open spaces; the permanent population only or the transient one too? 

While this gives urban planners something to disagree about, it risks missing the point: great urban places are not created by density; they’re created by intensity. The difference matters. When people describe the buzz of a market they don’t say, ‘Wow – it was so dense’. They’re much more likely to say how intense it was. Density is a word used by planners. Intensity is a word that real people use, and perhaps because it describes the outcomes that people experience rather than the inputs that have gone into creating them. It’s the outcomes that are ultimately more important.

But planning professionals like density. Even though density doesn’t capture the essence of what it feels like to be somewhere, the term appeals to professional instincts. It describes the raw ingredients that planners have to handle and, once you choose which version of the formula to use, density is easy to measure. It involves a simple calculation of straightforward urban quantities such as the number of people, of houses or of bedrooms, all divided by the geographic area over which those ingredients occur. Easy.

By contrast, intensity seems more difficult to pin down, not least because it appears to have a subjectively emotional dimension; it speaks of feelings, responses, stimuli; raising problems about how it can be measured. But intensity is also a response to context, to place and above all to people – and here we find clues to its measurement.

Queen elizabeth olympic park ii

Queen elizabeth olympic park ii

Space Syntax helped to shape London’s Olympic Park design so that it connected the communities to the west and east

So what are the factors that people are responding to when they instinctively feel the intensity of a great place? For a start, they can’t be calculating a planner’s measure of urban density because, even if they were so minded, they couldn’t possibly know about populations and geographic areas when they’re walking along a street or sitting at a café table in a public space. 

What people can respond to is what’s happening around them in the public realm: they can see how many other people there are, and they can see what these people are up to. In other words, intensity is obvious, immediate and instinctively calculable to the person in the street: not only the mobile population of walkers, drivers and cyclists, but also the immobile population of sitters, leaners and pausers. Intensity has a static as well as a kinetic dimension. Indeed the stationary people are the essential ingredient of intensity. They are the people who have chosen to be there, to add to the place through their semi-permanence and not simply pass through on the way somewhere else. So intensity is not about the population density of an area but the population that’s participating in the public realm of an area. This should be obvious, but any attempt to emphasise the benefits of static participation runs counter to the mindset of the traffic engineer and to the kinetic legacy of Le Corbusier, who described ‘grinding gears and burning gasoline’ as the pleasurable objective of the Plan Voisin. 

‘We end up with an urbanism of averages and a morphology of enclaves through an approach much too simplistic to create great places’

Intense places are ‘sticky’, especially when people are not only co-present in space but when they are also interacting: talking to each other, sharing thoughts, ideas, opinions. This is the essence of intensity; there is an exchange – a transaction – be it economic, social, cultural, intellectual, factual or simply facile. It’s the daily public life of every thriving village, town and city. It is unnoticed, unobserved and unmeasured. Until it’s not there. And that’s when you feel it most clearly.

Several years ago, Space Syntax was working on a sample of towns across the UK, some historic and some new. The towns had similar residential populations and similar retail floorspace provisions across similar geographical areas, in other words, similar densities. But what the team had also done was to count the numbers of people using the centres of each town: how many were walking and sitting in public space. They’d counted over several days, from morning until evening. What they found was that the historic towns consistently had many more people using their centres than the new ones – and they knew from other evidence that the historic towns had stronger economic performances. Here then were places with similar urban densities but different intensities of human activity.

What seemed to explain the differences between historic and new towns were, first, the spatial layout, and second, the street design of each place. The historic towns were laid out around radial streets that were designed to carry cars as well as larger vehicles and which met at the centre of the town in a public space. Behind these radial streets were more or less continuously connected grids of residential streets, interrupted by the occasional large open space. Both cars and pedestrians could use the residential streets, while the open spaces were generally for pedestrians only. There was some limited pedestrianisation in the very centre of each town.

‘The professions will be unwise if they avoid the opportunities presented by technology’

By contrast, the new towns often had separate street networks for vehicles and pedestrians, no high street or central public space, and usually a shopping mall or two. The central areas were typically pedestrianised and spatially separated from residential areas by a vehicle-only ring road; these residential areas were separated from each other by swathes of open space. 

To summarise, the key differences were in the intensity of the human experience, and in the design of the street network. Intensity, it seems, is facilitated by an alignment of physical and spatial factors: having the movement-sensitive land uses on sufficiently well-connected streets that are, in the main, shared by vehicles and pedestrians.

Importantly, both the amount of human activity and the degree of street connectivity are measurable commodities – if you know how to do it. It’s our day job at Space Syntax and it has two key parts: one part that takes place in the studio, using purpose-designed software that measures the amount of connectivity in street grids, and the other part that happens on site using some form of counting device. This device may be a camera strapped to a lamp post or, in recent years, a drone flight. Or it may simply be a set of human eyes, a pencil and a notepad. 

Onto these ‘foundational’ datasets is added other information, which might be about air quality, land value, crime rates or health outcomes. Statistical software is used to explore relations between the datasets: how is health or wealth or educational achievement related to spatial connectivity or isolation? The product of this process is called an Integrated Urban Model: a quantitative record of urban form and urban performance. A geographic information system (GIS) is used to hold the datasets in one place and a basic form of artificial intelligence is run to explore the links between the data. 

Fragmented city

Fragmented city

The fragmented city

However, it is possible to create a primitive version of a data platform using only PowerPoint and Excel. Space Syntax began its work before the Macintosh, before colour screens, before the internet, before CAD, before GIS and long before BIM. Its observations of pedestrian movements around Trafalgar Square were done with pen and paper, the results coded manually into a simple drawing programme. 

‘Intense places are “sticky”, especially when people are not only co-present in space but when they are also interacting’

What matters today is what mattered then: to bring data to life using maps and colours rather than spreadsheets and charts. This makes the information accessible to audiences making judgements about the future of places: investors, planning teams, politicians and local communities. Measures of intensity need to speak to multiple audiences, not least to the design community, into whose creative hands is entrusted the responsibility for shaping the aspirations of stakeholders. An Integrated Urban Model must be nimble, capable of responding again and again to the short and intensive programme of a rapid design process. Beware the Smart City ‘Control Room’ stuffed with technicians; embrace instead a portable platform that can respond to the timescale of a creative whim.

Why don’t we measure towns and cities in a systematic way? Why isn’t there a profession of urban intensity surveyors? And a culture among architects and urban planners of designing for intense human interactions?

The problems start when the responsibility for thinking about cities, streets and public spaces moves from the individual enjoying the buzz of the boulevard to the collective of professional institutions charged with creating place. Density prevails over intensity and we revert to simplifications. Assumptions are made, incorrectly, that the quality of street life will be in direct proportion to the density of people in an area. That if we have more people, then the streets will be busier, and the busier the streets, the better the place. But then the counterview is quite reasonably made that people need quiet streets and so densities shouldn’t be too high. A compromise is eventually reached: ‘Let’s not have super-high or super-low densities. Let’s not have towns that are too big or too small. And if we need big towns then let’s break them up into manageable parcels. Since we want pedestrians then let’s pedestrianise.’

Integrated city

Integrated city

The integrated city

We end up with an urbanism of averages and a morphology of enclaves through an approach much too simplistic to create great places. It’s not born of science and doesn’t reflect human experience: people know instinctively that you can turn off the busiest street in the city and immediately find yourself on a lane that is one of the quietest; that the intensity of the urban experience can transform itself in seconds. This is one of the joys of exploring great cities: they’re not pervasively busy; they are intensely quiet too. They have a foreground grid of busy streets and a background grid of quiet ones. If we systematically measure urban intensity then we will understand how towns and cities work in ways that will transform design practice. And by transforming practice we will transform place. 

The professions will be unwise if they avoid the opportunities presented by technology: of data capture, visualisation and analysis as well as broadband, social media, augmented reality (AR) and artificial intelligence (AI). Human activity is becoming more intense as a result of some of these technologies, providing another reason to systematically measure urban intensity. People are walking more slowly, ensconced in virtual worlds, while participating in physical space; seeing their surroundings augmented with pop-up information. The trend will continue as AR on our smartphones becomes AR on our spectacles. As well as talking to each other we will be talking to objects on display in shops, to screens in buildings and on streets, and to ourselves – our digital twin may appear as an avatar walking alongside us in our peripheral vision or in front of us when trying on clothes for us. This intensity of communication can already be seen in early-adopting countries, especially China, and it may seem strange at first. But there was a time, not long ago, when it seemed strangely ostentatious to put down a mobile phone on a table in a restaurant.

The brain has a finite processing capacity and so what goes into handling increased visual information will have to be taken away from the control of bodily function. People may therefore adapt to the amplified intensity of visual stimuli by moving ever more slowly. We will need more space for these intense activities and the obvious place is the street, where we will need more space for people. Road space will have to narrow and footways will have to widen. We will need more places to sit and lean – to be sticky.  This presents a choice for designers: continue to disagree about the best way to measure density, or embrace intensity and anticipate the radical transformation of place.

This piece is featured in the AR’s May 2018 issue on Intensity – click here to purchase a copy