Ivan Muñiz

Cubic Spline Population Density Functions and Satellite City Delimitation: The Case of Barcelona

The presence of satellite cities within large metropolitan areas cannot be captured by an exponential function. Cubic spline functions seem more appropriate to depict the polycentric pattern of modern urban systems. Using data from the Barcelona Metropolitan Region, two possible population satellite city delimitation procedures using cubic spline density functions are discussed: one, taking an estimated derivative equal to zero; the other, a density gradient equal to zero. It is argued that a delimitation strategy based on derivatives is more appropriate than one based on gradients because the estimated density can be negative in sections with very low densities and few observations, leading to sudden changes in estimated gradients. It is also argued that delimiting satellite cities using a second derivative with a zero value permits the capture of a more restricted area than using a first derivative zero. This methodology can also be used for intermediate ring delimitation.

Employment Decentralisation: Polycentricity or Scatteration? The Case of Barcelona

At the present time, most large cities in the world are polycentric and, at the same time, they are undergoing processes of employment decentralisation and deconcentration. It has been argued that polycentricity is just an intermediate stage between monocentricity and a more unstructured, chaotic and amorphous location model, scatteration. For the case of the polycentric Barcelona, the aims of this study are to test: whether its employment is moving from polycentricity to scatteration; and, whether its employment location model is increasingly random and unstructured. The results show that, in spite of the decentralisation and deconcentration processes, employment concentrated in centres still represents a significant percentage of total employment and new sub-centres have emerged in the periphery. What is more, the results also show an increasing influence of employment sub-centres on employment location and density conditions. As a result, polycentricity has been reinforced.

The Effect of Employment Sub-centres on Population Density in Barcelona

The polycentric models of the new urban economics (NUE) predict that population density decreases while increasing the distance to employment centres. In contrast with this, some studies have calculated non-significant gradients or even positive ones, which appear to threaten seriously the usefulness of these theoretical models. Does this mean that this theoretical framework should be given up in order to understand the decision-making processes of the actors in a polycentric city and their cumulative effects on urban structure? Or, rather, is it a matter of overcoming problems with the appropriate estimating techniques? This study has tested the effect of decentralised and integrated sub-centres in the Barcelona metropolitan region on population density in 1991 and 2001. From the preliminary results, it is clear that population density increases with distance in a considerable number of the sub-centres that have sprung up as employment has decentralised. It has been detected that this result is due not so much to the higher value of more distant residential land compared with that nearer the employment sub-centres, but to deficiencies in the econometric model used. The problem is that the sub-centres belonging to this group are very close together. Once this is resolved, it is demonstrated that, although distance has less effect on decentralised sub-centres than integrated ones, in both cases the effect is negative; that is, when distance increases, population density is reduced. Therefore, the results obtained are not clearly contrary to the predictions of the theoretical models.

The Polycentric Knowledge Economy in Barcelona

This study focuses on the employment decentralization process in the Barcelona Metropolitan Region (BMR) between 1991 and 2001. Disaggregating employment data among four categories of knowledge-intensive activities (Knowledge-Intensive Services; High- Technology Industries; Producer Services; and Finance, Insurance, and Real Estate) and two groups of other employment (Other Manufacturing and Other Services), the aim is to test whether these four groups decentralized in a similar way to other employment, and whether this process encouraged them to locate in a polycentric or spatially dispersed pattern. The results show that knowledgeintensive and other employment activities decentralize in a similar way, although the former tends to be more concentrated through the formation of employment subcenters and therefore follows a polycentric location model. As a result, physical proximity is still important for numerous activities, especially those that incorporate more knowledge.

Anatomía de la dispersión urbana en Barcelona

No existe una definicion comunmente aceptada de dispersion urbana (urban sprawl), de modo que la investigacion aplicada ha trabajado con diferentes indicadores que pretenden a su vez capturar los distintos significados con que se ha dotado al termino. En este trabajo se mide como ha evolucionado la dispersion de la poblacion y del empleo de la Region Metropolitana de Barcelona (RMB) entre 1986 y 2001. Las dimensiones exploradas se dividen en dos grupos: i) forma urbana (desconcentracion, baja densidad y discontinuidad) y ii) estructura urbana. A diferencia de algunos trabajos donde el policentrismo y el crecimiento lineal se presentan como dos formas de dispersion, en nuestro caso contraponemos la idea de expansion urbana estructurada (lineal o policentrica) con la de expansion urbana desestructurada (amorfa, caotica o aleatoria), equiparando esta ultima con la cuarta dimension de la dispersion. Los resultados obtenidos indican que la poblacion y el empleo de la RMB se han descentralizado de forma desconcentrada y la densidad residencial se ha reducido. Sin embargo, la RMB no ha crecido de forma discontinua ni desestructurada, sino todo lo contrario.

Estructura espacial y densidad de población en la ZMVM 1995-2010: evolución de un sistema urbano policéntrico

En este trabajo se estima el efecto del policentrismo sobre la densidad de poblacion en la Zona Metropolitana del Valle de Mexico (ZMVM) entre 1995 y 2010. Los modelos teoricos policentricos postulan que la densidad de la poblacion debe caer a medida que la distancia a los centros de empleo aumenta. Los resultados confirman esta hipotesis a pesar de la fuerte inercia monocentrica del area. Sin embargo, se advierte una creciente desconexion entre los espacios de empleo y los de vivienda, lo cual impediria reducir la distancia de los desplazamientos entre el lugar de residencia y el de trabajo. Un producto destacable del ejercicio llevado a cabo es que la capacidad estructurante que tiene la infraestructura viaria principal tiende a reforzarse en detrimento del efecto que ejercen los subcentros de empleo sobre la densidad de poblacion.

Forma urbana y Huella Ecológica en el Área Metropolitana de Concepción (Chile)

One of the most controversial aspects of the debate on urban sustainability is to what extent the overall environmental impact of cities is determined by their shape and spatial structure. Compact City Approach defenders argue that people living in the densest and central areas of large cities have low environmental impact. Residential density and distance to the Central Business District (CBD) are the most common indicators proposed to capture urban spatial structure of cities. In this paper we estimate the carbon footprint of residential energy consumption, commuting and leisure purposes mobility from 475 surveys conducted in Concepcion Metropolitan Area (Chile). After controlling for potential endogeneity problems and taken into account the socioeconomic aspects that may affect the value of the carbon footprint, residential density does not exercise significant influence, so compactness policies could prove ineffective. The results rule out that this result is due to the existence of compensatory behaviors that lead to abnormally high mobility for leisure purposes in denser areas. Income is the main element explaining the observed variability in footprint values.