How does the layout of a city affect its economic success?

A scale model of Beijing, 2007. Image: Getty.

How does the layout of a city affect its performance? And what are the opportunities and challenges of spatial evidence in policy? Centre for Cities discussed these issues at a recent roundtable with urban planning consultancy Space Syntax.

Space Syntax studies the impact that the physical layout of cities has on the social, organisational and economic performance of urban areas. Developed by researchers at The Bartlett (University College London’s global faculty of the built environment), this theory is used to give streets an ‘accessibility’ score, denoting how well a street is linked to the wider layout of a city: for example, if it is a dead end, its score would be low. Streets are then plotted on a map using different colours for different levels of accessibility – with red meaning more accessible streets and cold colours like blue representing less accessible ones.

The physical fabric of a place has an impact on its performance. One of the examples discussed on the day was the comparison between Ashford, Kent, which has grown over a number of centuries, and the new town of Skelmersdale in West Lancashire.

The two cities have different layouts and this has consequences in terms of city centre accessibility and land use. In Ashford, most streets are interlinked with one another, creating an accessible town centre:

Streets Accessiblity in Ashford.

By contrast, the centre of Skelmersdale is characterized by fragmented streets with many more dead ends. These separated movements make the city centre inaccessible.

Streets accessibility in Skelmersdale.

The accessibility of streets affects land use. Ashford town centre is more accessible, and has a combination of retail and catering businesses, commercial activities and offices, houses and services, all in close proximity.

Land use in Ashford town-centre. 

By contrast, land use in Skelmersdale town centre is much more fragmented (figure 4). The Concourse Shopping Centre dominates the town centre while offices, houses and services are broadly segregated in three different parts.

Land use in Skelmersdale town-centre.

The wider body of research shows that the layout of a city has an impact on a wide range of issues such as crime, social inclusion, poverty, and health. Understanding that impact – and better communicating the implications to policy-makers – has the potential to bring about positive change to the everyday lives of the people who live and work in urban areas.

In conjunction with the researchers at UCL, we will be doing more work in the coming months on the implications of spatial design for policy makers at the local and national level.

Elena Magrini is a researcher at the Centre for Cities, on whose website this article originally appeared.


 

 
 
 
 

Where did London’s parakeets come from?

Parakeets in the skies above Wormwood Scrubs, west London. Image: Getty.

Visitors to London’s many green spaces would have to be stubbornly looking at their feet to not see one of the UK’s most exotic birds.  Dubbed “posh pigeons” by unimaginative Londoners, these brilliant green parakeets stand out among the fauna of Northern Europe’s mostly grey cities.

‘Parakeets’ is actually an umbrella term referring to the multiple species, which can now be found in London, Amsterdam, Brussels, Paris and various German cities. By far the most common is the Indian ring-necked parakeet, easily recognisable by the stylish red ring around their neck, a matching red beak and, of course, the loud squawking.

In the last 50 years these migrants from South Asia have arrived and thrived, settling into their own ecological niche. In the UK, London is a particular stronghold, but although they may have originally settled in the leafy streets of Twickenham, the birds can now be found in cities as far north as Glasgow.

The story of how they ended up in London is a matter of some discussion and plenty of myth. One often reported theory is that the capitals’ current population are the descendants of birds that escaped from Shepperton Studios during filming of The African Queen, starring Humphrey Bogart and Katharine Hepburn. Others would tell you that they escaped from Syon Park in the early 1970s, when a piece of debris from a passing plane damaged the aviary and allowed them to escape. This chimes with their original concentration in South West London.
My favourite story by far is that they were released by Jimi Hendrix on Carnaby Street in the late 60s. Bored of London’s grey skyline, he set the little fellas free to liven up the place.

However they got here, from 1970 onwards their numbers boomed. In 1992, 700 birds were recorded in London Bird Report. By 1998, 2,845 were seen in the London Area, and by 2006 the ring-neck parakeet was 15th most sighted bird in London.


Darwin would be proud at how well they adapted to the new environment. Toughened up by the hard Himalayan climate, they handle the cold northern European winters better than most locals. Global warming is often brought up in discussions of the parakeets, but it is certainly only part of the story.
It helps, too, that the birds have a 35 year lifespan and few local predators, enabling them to breed freely.

As with any new species, the debate has raged about whether they are harmful to the ecosystem. Strangely reminiscent of the debate over human migrants, often the birds have often been accused of stealing the homes of the natives. The parakeets do nest in tree cavities also used by jackdaws, owls and woodpeckers – but there is little evidence that native species are being muscled out. 

The also provide a food source for Britain's embattled birds of prey. Owls and peregrine falcons have been know to eat them. Charlie and Tom, two city dwelling falcons monitored by Nathalie Mahieu, often bring back parakeets as food.
Of more concern is the new arrivals’ effect on plants and trees. By 2009 their numbers in the UK had grown so much that they were added to the “general licence” of species, which can be killed without individual permission if they are causing damage.

And Parrotnet, am EU funded research project studying the development of parakeet populations across Europe, has warned of the risk they pose to agriculture. In their native India, the parakeets are known to cause widespread damage to crops. As agriculture develops in the UK in line with warmer climates, crops such as maize, grapes and sunflower will become more popular. In India the birds have been documented as reducing maize crops by 81 per cent.

So the parakeets remain divisive. Environmentalist Tony Juniper has disparagingly described them as “the grey squirrel of the skies”. By contrast, the University of York biologist Chris D. Thomas has argued that the parakeets should be left free to move and breed. He sees those wary of the parakeet boom of “irrational persecution” of the bird.

For good or ill the parakeets are here to stay. As so often with migrants of all kinds, there has been some unease about the impact they have had – but the birds, popular amongst Londoners, certainly add colour to the city. Thriving in the urban environment thousands of miles from their natural habitat, they are a metropolitan bird for Europe’s metropolitan cities. 

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