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| Software helps to identify sustainable urban policiesWithout radical and integrated transport and land use policies, the quality of life in European cities is set to decline significantly over the next few decades. Computer models and analytical tools developed by the PROPOLIS project reveal that a sustainable future is possible only if city authorities introduce comprehensive packages of measures that address car use, public transport, and land use together.
"City life depends so much on transport and land use strategies," says Kari Lautso. "Policies in these areas have profound environmental, social and economic impacts. Every city in Europe knows this. It is critical to find and develop tools that will identify urban policies and strategies that cities can adopt to promote long-term sustainable growth."
Lautso’s firm, LT Consultants Ltd, has considerable experience of transport and land use planning. But it took a wider European project to assemble enough knowledge and expertise to develop a comprehensive analysis and forecasting tool. The project brought academic institutions together with transport and land planning departments from the city authorities in seven European cities.
The modelling tool uses a set of 35 key indicators that describe each urban setting - a sort of picture in numbers. The indicators cover environmental, social and economic sustainability and include objective measures such as acidifying gases from transport, traffic injuries, housing standards, exposure to noise and pollutants and transport investment costs.
"The choice of indicators was extremely important," explains Lautso. "Lots of indicators are suitable for monitoring purposes, but for PROPOLIS it was essential that they could also be used to forecast the future. That ruled out many indicators. We also had to choose indicators for which each of our case study cities could produce values." Values are calculated from existing data, using enhanced urban land use and transport models and new GIS-based systems.
The PROPOLIS analysis tool is particularly powerful because it iteratively calculates the value of each indicator over a period of twenty years or more for a variety of scenarios. "The computer modelling tool uses the calculated values of different characteristics of urban land use and transport systems to work out the locating process of households and firms through time, for example," says Lautso. "This approach is the platform for revealing innovative policy recommendations, as the system is able to show multiplier effects and interactions between the different indicators. You see the whole chain of effects that a change in a policy may have on any of the indicators."
So far the PROPOLIS project has simulated different policy scenarios in Helsinki, Dortmund, Inverness, Naples, Vicenza, Bilbao and Brussels. Chosen for the variety of their sizes and cultures, these cities already had existing urban land use and transport models available, from which the PROPOLIS system could be developed.
The bad news is that if we do not actively implement policies to address the sustainability of urban transportation and land use, city life is destined to worsen rapidly. "Environmental sustainability - and often social sustainability, too - are tending to deteriorate due to global climate change, an increase in the consumption of natural resources, and an increase in traffic leading to more traffic accidents, congestion and pollution." says Lautso. "Even when we included known, city-specific plans such as investment programmes, the deteriorating trend remained. Our so-called reference scenarios for 2021 show that in all seven cities sustainability will degenerate."
Further analyses with the PROPOLIS analysis tools show that single policy changes will not improve sustainability. For instance, when you reduce maximum speed limits by 10% you naturally get a reduction in traffic accidents, but people end up spending longer on the road, and air pollution increases too. Different types of land use policies also had little overall effect although locally they may be important.
The good news is that the PROPOLIS researchers did manage to improve most indicators in each city, by selecting combinations of car, public transport and land use policies. These ‘policy packages’ - sticks and carrots - work synergistically to make a real difference. Indeed, in some cases, sustainability indices better than in 2001 were achieved.
For all seven cities, the best results were achieved with a combination of car pricing policies and simultaneous improvements to public transport involving reduced fares and better speed and service. Together, these policies produced a 15-20% reduction in CO2 emissions, 8-17% reduction in road traffic accidents, a decrease in exposure to noise and pollutants, and improved accessibility to the city centre and services. In economic terms the benefits of combined policies were worth EUR 1 000-3 000 per inhabitant (net present value).
"These results obviously have limitations, which the participants intend to address with further research," warns Lautso. "Nevertheless, the results in different cities, different cultures and using different models all point in the direction of integrated policy-making."
Lautso believes that PROPOLIS will make an important contribution to European sustainability. "We believe that our general findings must be heeded to ensure that urbanisation is held in check, so that it contributes to long-term sustainability. We are confident that we can now at least generalise on strategies that improve urban sustainability in general and radically reduce urban pollution and congestion without compromising economic efficiency and social sustainability."
Cities across Europe will study the project’s recommendations with interest, especially as the analysis tools are now tried and tested. Lautso is hoping that some authorities will put the project’s theories into practice.