Spatial Complex Network Analysis and Accessibility Indicators: the Case of Municipal Commuting in Sardinia, Italy

In this paper a contribution is presented with respect to accessibility indicators modelling for commuters moving through the municipalities of Sardinia, in Italy. In this case, spatial complex network analysis is integrated into the construction of accessibility measures: one of the most relevant outcomes of the first tool –the detection of shortest road paths and distances- is adopted as an input for the second in modelling accessibility indicators. Instead of Euclidean distances often adopted in the literature, shortest road distances are chosen, as commuting implies movements that are usually repeated daily and very likely subjected, even unconsciously, to space and time minimization strategies. In particular, two commuter accessibility indicators are constructed according to approaches based on a travel cost and a spatial interaction model with impedance function calibrated in exponential and in power form. The accessibility indicators are confronted each other and with relevant socio-economic and infrastructure characteristics of Sardinia. In addition, they are described, with respect to their spatial distribution and their different implications, when adopted in decision-making and planning. The travel cost based accessibility indicator has a municipal spatial distribution strongly influenced by the main road infrastructure of the Island. By contrast, spatial interaction model based accessibility indicators are more reliable, with respect to their capacity to confirm a leading socio-economic role of the municipalities comprehended in the metropolitan area of the capital town Cagliari

The structure of Inter-Urban traffic: A weighted network analysis

We study the structure of the network representing the interurban commuting traffic of the Sardinia region, Italy, which amounts to 375 municipalities and 1,600,000 inhabitants. We use a weighted network representation where vertices correspond to towns and the edges to the actual commuting flows among those. We characterize quantitatively both the topological and weighted properties of the resulting network. Interestingly, the statistical properties of commuting traffic exhibit complex features and non-trivial relations with the underlying topology. We characterize quantitatively the traffic backbone among large cities and we give evidences for a very high heterogeneity of the commuter flows around large cities. We also discuss the interplay between the topological and dynamical properties of the network as well as their relation with socio-demographic variables such as population and monthly income. This analysis may be useful at various stages in environmental planning and provides analytical tools for a wide spectrum of applications ranging from impact evaluation to decision-making and planning support.Comment: 12 pages, 12 figures, 4 tables; 1 missing ref added and minor revision

The GIS Architecture Elements for the Coastal Areas Along the Adriatic Sea

The study of the national and cross-border Adriatic coastal areas will be approached by using an interdisciplinary method. A comparative reading will focus on an analysis of the main variations undergone by the area and will try to define all the elements involved in those areas where a conflicting presence exists between high quality environmental factors on the one hand and anthropological aggression on the other. In this paper we present the aim of the GES.S.TER. project, that is the creation of a protocol for territorial analysis – namely the G.I.S.A.E. Adriatic (Geographical Information System for Activities along the Coast). The Project is financed by the Interreg IIIA Programme Adriatic Cross Border from 2004 to 2007 (prof. Donatella Cialdea is the Head of GESS.S.TER.). Moreover the Project will be a case-study analysed by the GISIG - Geographical Information Systems International Group. The areas covered by the project include the national Adriatic coast, in particular the coastal area of Molise, and the cross-border coasts of Albania and Croatia (both partners in the project). In the definition of the characteristics that a territorial information system of aid to the GES.S.TER project should have, the parameters for the collection of data and for the reordering of the information, which was already in our possession, have been established. Another necessary step has been that of revising and coordinating the existing sources, keeping in mind that the final purpose of the system is to define the objective landscape qualities, we find ourselves having to face the problem of combining, and consequently, comparing, information coming from different sources. Five resource systems have been selected: physical-environmental; landscape-visual; historical-cultural; agricultural-productive; Demographic-tourism. A further source of information comes from the analysis carried out during the drawing up of the Vast Area Environmental Landscape Territorial Plans and we have defined the criteria for the selection of the indicators. These indicators will be useful for an evaluation of transformations through time of the territories, in order to prepare the documents for the strategic environmental assessment procedures too.

Modeling commuting systems through a complex network analysis: a study of the Italian islands of Sardinia and Sicily

This study analyzes the inter-municipal commuting systems of the Italian islands of Sardinia and Sicily, employing weighted network analysis technique. Based on the results obtained for the Sardinian commuting network, the network analysis is used to identify similarities and dissimilarities between the two systems

Grouping complex systems: a weighted network comparative analysis

In this study, the authors compare two inter-municipal commuting networks (MCN) pertaining to the Italian islands of Sardinia and Sicily, by approaching their characterization through a weighted network analysis. They develop on the results obtained for the MCN of Sardinia (De Montis et al. 2007) and attempt to use network analysis as a mean of detection of similarities or dissimilarities between the systems at hand

Emergent topological and dynamical properties of a real inter-municipal commuting network - perspectives for policy-making and planning

A variety of phenomena can be explained by means of a description of the features of their underlying network structure. In addition, a large number of scientists (see the reviews, eg. Barabasi, 2002; Watts, 2003) demonstrated the emergence of large-scale properties common to many different systems. These various results and studies led to what can be termed as the “new science of complex networks” and to emergence of the new “age of connectivity”. In the realms of urban and environmental planning, spatial analysis and regional science, many scientists have shown in the past years an increasing interest for the research developments on complex networks. Their studies range from theoretical statements on the need to apply complex network analysis to spatial phenomena (Salingaros, 2001) to empirical studies on quantitative research about urban space syntax (Jiang and Claramunt, 2004). Concerning transportation systems analysis, interesting results have been recently obtained on subway networks (Latora and Marchiori, 2002; Gastner and Newman, 2004) and airports (Barrat et al, 2004). In this paper, we study the inter-municipal commuting network of Sardinia (Italy). In this complex weighted network, the nodes correspond to urban centres while the weight of the links between two municipalities represents the flow of individuals between them. Following the analysis developed by Barrat et al. (2004), we investigate the topological and dynamical properties of this complex weighted network. The topology of this network can be accurately described by a regular small-world network while the traffic structure is very rich and reveals highly complex traffic patterns. Finally, in the perspective of policy-making and planning, we compare the emerging network behaviors with the geographical, social and demographical aspects of the transportation system.

The GIS Architecture Elements for the Coastal Areas Along the Adriatic Sea

The study of the national and cross-border Adriatic coastal areas will be approached by using an interdisciplinary method. A comparative reading will focus on an analysis of the main variations undergone by the area and will try to define all the elements involved in those areas where a conflicting presence exists between high quality environmental factors on the one hand and anthropological aggression on the other. In this paper we present the aim of the GES.S.TER. project, that is the creation of a protocol for territorial analysis – namely the G.I.S.A.E. Adriatic (Geographical Information System for Activities along the Coast). The Project is financed by the Interreg IIIA Programme Adriatic Cross Border from 2004 to 2007 (prof. Donatella Cialdea is the Head of GESS.S.TER.). Moreover the Project will be a case-study analysed by the GISIG - Geographical Information Systems International Group. The areas covered by the project include the national Adriatic coast, in particular the coastal area of Molise, and the cross-border coasts of Albania and Croatia (both partners in the project). In the definition of the characteristics that a territorial information system of aid to the GES.S.TER project should have, the parameters for the collection of data and for the reordering of the information, which was already in our possession, have been established. Another necessary step has been that of revising and coordinating the existing sources, keeping in mind that the final purpose of the system is to define the objective landscape qualities, we find ourselves having to face the problem of combining, and consequently, comparing, information coming from different sources. Five resource systems have been selected: physical-environmental; landscape-visual; historical-cultural; agricultural-productive; Demographic-tourism. A further source of information comes from the analysis carried out during the drawing up of the Vast Area Environmental Landscape Territorial Plans and we have defined the criteria for the selection of the indicators. These indicators will be useful for an evaluation of transformations through time of the territories, in order to prepare the documents for the strategic environmental assessment procedures too