B. Murgante, G. Borruso, A. Lapucci (Eds.): Geocomputation & Urban Planning, SCI 176, pp. 37–56. springerlink.com © Springer-Verlag Berlin Heidelberg 2009 A Tale of Two Cities: Density Analysis of CBD on Two Midsize Urban Areas in Northeastern Italy* Giuseppe Borruso and Andrea Porceddu Department of Geographical and Historical Sciences, University of Trieste, P.le Europa 1, 34127 Trieste, Italy giuseppe.borruso@econ.units.it, andrea.porceddu@econ.units.it Abstract. The paper is focused on the observation of urban form and functions and is aimed at identifying a method for the cartographic definition and representation of CBD (Central Busi- ness District). The analysis is developed to explore the formation of centers of different order in the urban environment, starting from the locations of a selected set of human activities located in urban areas. An index of concentration of central activities is presented to allow the visualization of the functional urban environment by means of a density surface, therefore high- lighting areas where central activities and functions concentrate. The paper is based on analyses related to spatial statistics in a GIS environment. We provide a short review of the literature on CBD research, briefly describe the kernel density estimation method, and propose how this can be used in order to test the index of concentration of activities and therefore delineating CBD, presenting evidence from two urban areas in Northeastern Italy (Trieste and Udine). Keywords: Central Business District, Kernel Density Estimation, GIS, Nearest Neighbor Analysis, Trieste, Udine. 1 Urban Analysis and the Definition of Centers The Central Business District as a geographical concept is to-date quite settled and has been examined through the years by the researchers in many different urban con- texts around the world. The activities carried on in the CBD have changed during the years, as well as the same location of many Business Districts that, in time, have often abandoned a central location in favor of more decentrated ones where central con- straints - high rents, competition for land use, lack of floor space suitable for large businesses, traffic congestion - limit to-date financial and directional activities locat- ing in the 'true' geographical centre of an urban area. However, centers maintain their importance in shaping cities and orientating their functions and roles. Despite some activities move out from the centers, many ones remain there, therefore characterizing central urban landscape and functions. Studies intended to highlight functional areas within urban areas have drawn the attention of geographers and scholars from other disciplines, as urban ecologists, * The paper derives from joint reflections of the authors. Chapter 1, 2.1, 2.2, 3.1, 3.3, 3.3.1, 4.1, 4.3 and 5.1 are realized by Giuseppe Borruso and chapter 2.3, 3.2, 3.3.2, 4.2 and 5.2 by An- drea Porceddu. In general, elaborations and comments on Trieste were performed by Giuseppe Borruso, those on Udine by Andrea Porceddu.