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04.09 Contributi The externality concept assumes an important role inside the classic microeconomic theory and it has been widely discussed in the literature since 1920 (Pigou 1920; Scitovsky 1954; Buchanan and Stubblebine 1962; Baumol and Oates 1988). Some specific studies about transportation externalities are the ones by Verhoef (1996) and Green et al. (1997). The externalities produced by transportation systems can be negative (e.g. air and noise pollution) or positive (e.g. a new metro line that improves the value of buildings in its influence areas); in the following the paper will focus on the main negative externalities of transportation systems. Examining the different definitions, it can be summarised that a negative externality is a cost that is produced by subject A and is borne by subject B; moreover, subject A does not consider the effects of his/her behaviour on subject B and does not compensate subject B for the costs that this last one is forced to bear. In the field of transportation systems, in general, subject A represents the users and subject B represents the whole collectivity. Beginning from ’90 the interest for the external cost evaluation produced by transportation systems is really increased, mainly for the numerous studies on the effects produced by greenhouse gas emissions on climate changes. The importance of evaluation of external costs has been highlighted in several documents of international and communitarian policy (European Commission 2001; United Nations 2005). In particular, the European Union has promoted and financed several research projects in this field (EXTERNE 2005; COPERT 2005; UNITE 2005). The Kyoto Protocol, to which the European Community countries agreed, indicates the greenhouse gases reduction objectives; in this context, transportation systems are one of economic sectors with the higher impact on emissions. Therefore, estimating external costs assumes an important role inside the evaluation of transportation projects, plans and policies. The aim of this paper is to propose some simplified procedures for estimating the main transportation external costs in regional areas, using available national and/or regional statistical data, without the need of specific surveys, and the results of other specific studies on external costs developed in Italy and in Europe. The proposed procedures are applied to the region of Campania (Italy), but they can be applied without difficulties to other regions in Italy and, if the data are available, also to regions of other European Countries. Since the proposed procedures are based on some simplifying assumptions, that are not removable without specific (expensive) surveys, the obtained results should be seen as an approximate estimation of external costs useful in preliminary studies. This paper will focus only on the methods for estimating

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the main external costs without examining how part of them are eventually already internalised (if there is a positive difference between taxes paid by users and service production costs); this problem will be object of further researches. The outline of the paper is the following: section 2 focuses on definitions and literature review, identifying the main and the secondary transportation external costs, the kinds of external costs (total, medium or marginal) and some studies about their estimation; in section 3 methods for estimating the main total external costs (greenhouse gas emissions, air pollution, noise, accidents and congestion) using the statistical data available for Italian Regions are proposed and are applied to the case of the region of Campania; section 4 discusses the obtained results; section 5 summarises conclusion and research perspectives.

Definitions and literature review The external costs produced by transportation systems can be classified in two groups: main costs and secondary costs. The main costs are the ones that are quantitatively prominent and that have been studied in the literature more or less widely. The secondary ones are the costs that produce less important and/or not easily quantifiable effects; in general, they have not been studied systematically. The main external costs are due to: – greenhouse gas emissions; the greenhouse gases (CO2, CH 4, H2O, N2O, O3, etc.) are naturally present in the atmosphere and, therefore, are not assumed as pollutants from a technical point of view. The high concentration of these gases (mainly the CO2) increases the greenhouse effect, producing an increase in the average temperature of the planet, with serious climatic consequences. – air pollution ; transportation engines emit in the atmosphere some pollutants (SO2, NOx, PM10, CO, etc.). An high concentration of these gases cause damages to human health, buildings and cultivations. – noise; transportation systems are noise sources. Besides disturbance, the noise produces health damages to residents in the more exposed zones. – accidents; transportation accidents, mainly caused by road systems, are an important social problem. The costs produced by accidents are almost totally assumed as external, because the users do not perceive the accident risk and because the accident costs fall prevalently on collectivity (e.g. pain and suffering imposed to others). – congestion; the increment of transportation costs due to congestion is not captured by the price system so the congestion costs are assumed as external, even if

TeMA 04_09 FLUSSI METROPOLITANI  
TeMA 04_09 FLUSSI METROPOLITANI  

TeMA is the official journal of the TeMA Research Group of the Urban and Regional Planning Department of the University Federico II of Naple...

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