Since early 2004 I've been on the advisory group for the SOLUTIONS project - it's a broad study focusing on spatial policy, transport systems and built form, in outer urban areas of England that are likely to experience growth pressures in the future.
Researchers from six universities have worked on strategic modelling of transport and planning issues to the year 2031, and local neighbourhood studies exploring the sustainability implications of various transport options and settlement structures. I've just come from the final conference and am struggling to piece together the key messages.
We can start with the predictable I suppose: existing land use patterns in outer urban areas are unsustainable, both environmentally and socially. The team looked at three main models that policy might promote, alongside the 'existing trend':
- compact city - high density development related to public transport and located within existing towns and cities
- market led dispersal - medium to low density development oriented towards travel by car
- planned expansion - new settlements and suburbs built at medium densities and oriented towards both public transport and cars.
Here are some examples of the kinds of subtleties that emerge once the models have been crunched:
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In the compact city, higher density reduces land take relative to the trend by 40%, but dwelling choice and space declines, and surface sealing / flood risk increases. Compact development results in a small reduction in resource use and environmental damage but has negative social and economic impacts.
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Under market-led dispersal, there is an increase of about 2% in total CO2 emissions, and 13% in construction materials, but increases in surface sealing / flood risk are least.
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Under planned expansion policies, new settlements would improve space standards relative to the trend, but results are highly dependent on attracting basic employment to the new settlements.
Got that? So it turns out that the difference between the spatial options is relatively small; road user charging would offer more significant benefits; and improvements to sustainability are likely to require technological improvements and behavioural changes.
From the local study work it seems that the critical factor in determining the level of active travel, for both car owners and non-owners, is distance. There is consistency across different kinds of neighbourhood in the distance people are prepared to walk.
'If localities are planned so that facilities are accessible by foot - within certain distance thresholds - then there will be more active travel, a more socially inclusive environment and greater opportunity for people to cut car use and carbon emissions.'
Hugh Barton of the University of the West of England argues for greater autonomy for local planners, to reflect the finding that
'the variation between different places is not marginal, it's huge.'
He also suggests that density is not the main factor in affecting people's behaviour and experience of locality.
Keep an eye out for more outputs from this research over the coming months.
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