This will not be possible if the effects of these policies cannot be clearly demonstrated including also the distribution of the effects between different socio-economic and other groups. It has also been shown that many of the policy options may have negative unexpected side effects, some policy options may work against each other, whereas some may reinforce each other. Some policy options may improve the situation in part of the region, whereas in other parts the situation may get worse. Hence, the definition of sustainable urban policies is not a straightforward task. The effects have to be identified and measured in a transparent way and this calls for advanced systems and methods.
Most cities have a transport model for planning of policies.
These models do not take into account the long-term interaction between land use and transport which severely limits their usability for strategic long term urban planning. Some cities have a combined land use and transport model for these purposes but, as strategic models, they don't produce information on detailed spatial level and cannot, thus, express important effects such as exposures to emissions or noise. They also lack a coherent system for assessing the effects in a systematic and comprehensive way taking into account the environmental, social and economic dimensions of sustainability. Furthermore, approaches which ignore land use interaction are likely to overlook important policy effects simply because there is much more inertia in the land use system and by their nature land use impacts tend to be much longer term. Indicators Indicators will be used to measure the above three dimensions of urban sustainability.