Costs and Benefits of Urban Dispersion on a Local Scale

There is an increasing urbanization of the world population. The city today is quite different from its former self. The old city was compact and continuous. In the emerging city the pattern of mobility has transformed social and spatial relations. Urban settlements interpenetrate with green spaces and the urban structure is becoming fragmented and dispersed.
With few defenders amongst the intelligentsia, urban sprawl in European countries is today a reality, one that is not planned but which is practised and accepted.
For some time urban sprawl has been a controversial issue. According to some authors it means contact with nature, space and intimacy; according to others it means imitation of nature, isolation, anonymity. Such subjective arguments are important in the identification of different concepts of quality of life.
However, for others, additional objective arguments should also be taken into consideration. These include land consumption, costs of public infrastructure, mobility costs and housing prices.
This project seeks opinions on this problem which are as precise as possible which explains why it is set up to consider costs and benefits.
In this kind of cost quantification approach, which is mainly to be found in the United States, analyses often focus on dispersion on the regional scale. In this case, we intend to compare the costs between different “Base Land Units” of the expanded city – a concept similar to that of city block or neighbourhood unit.
To achieve the goals of the project, we intend to study the literature, examine existing studies (even if they relate to a different territorial scale) and, crucially, analyse two different case studies – Aveiro/Ílhavo and Évora, two average Portuguese cities in the central and southern regions of Portugal respectively. They have completely different morphological and typological characteristics (and also types of dispersed occupation).
At the end the main goal is to confront costs with benefits, if this should prove possible.
By benefits we understand quality of life, a concept that changes from opinion group to opinion group. We intend to transform this concept into an algorithm which integrates this variability, based on the current literature, similar previous studies and on the answers to a questionnaire applied to the inhabitants of the two case study cities.
With respect to costs, we may divide them into two different types: local public infrastructure and mobility related costs. Quantification of costs relating to land consumption and other environmental externalities (nature and landscape based) has to be left for a later research opportunity.
To quantify the costs relating to local public infrastructure (all types of infrastructure systems, public spaces and public equipment) we will focus on the construction costs and, if possible, on management and conservation costs. To this end we will take into consideration existing studies and our case studies.
We will consider a range of scenarios, comparing infrastructure service with number of users, and evaluating the respective costs.
To analyse mobility costs we will use previous studies to quantify integrated costs (financial and environmental) per kilometre and per user for each transportation type. These will then be applied to our case studies.
In this field we will also experiment with alternative mobility organization scenarios.
Our conclusions, supported by public questionnaires, will be expressed quantitatively: a utility function to represent the opinions on quality of life; an integrated cost for local infrastructure + mobility; and a methodology to relate the two functions for a variety of scenarios.
This will result in the formulation of a comparative opinion, expressed in cost-benefit terms, between the various typologies of dispersed occupation and, also, between these and those of continuous occupation.
To formulate an operative proposal regarding urban dispersion, it is important to understand how the market works (in terms of its agents, procedures and prices) for current dispersed occupation dynamics.
Relevant literature will allow typification of applicable market factors. Questionnaires for the inhabitants, the promoters and mediators will show how the market is operating in our case studies.
This information will be sufficient to formulate recommendations for the management of the city:
- relative to the classification/rationalization of existing dispersion;
- relative to the dynamics of urban sprawl.