The Relations Between Regional Economic Development And Evolution Of Transport Demand In Italy

PUBBLICAZIONE PRESENTE IN GOOGLE SCHOLAR CON DUE CITAZIONI. ABSTRACT The field of transportation plays an essential role both in the economy and the society: a direct relationship between growth of the Gross Domestic Product (GDP) and tendency of the transport demand can be therefore reasonably stated. First of all, it is quite logical to assume that the economic growth induces person and freight mobility: increasing the production of goods (either in absolute or in added value) means inducing bigger movements of persons (in order to produce and to consume) and visible trades of freight. The second reason is both practical and historical: even if lots of social and economical phenomena are strongly influenced from their initial conditions, a wide-ranging regularity does not completely guarantee an univocal future evolution. In the present case, on the contrary, both an in-depth study of Leontieff’s input-output matrices and the reading of the available data and estimations confirm that the GDP and transport demand have had concordant trends. In other words, the whole economical system was shown to have the “quality” of stability: its floating data population evolves through intermediate states, which can be observed and controlled. In Italy, this procedure was introduced for the first time by Wassily Leontieff and Paolo Costa for the 1986 General Transport Plan (PGT). The method was then nationwide used in various studies, becoming a standard procedure, which often applied the same Leontieff’s evolution ratios (recently, it was expounded again to national level - Iannone, 2003). The same procedure is been used in recent European Union White Paper (2001). This study intends to verify the correlation level between variations in GDP and variations in national traffic flows in Italy also on a regional scale. The values of GDP, from 1980 to 2003, are related to the flows of passenger and freight traffic (passenger-km, tons-km) by rail (source: Trenitalia) and motorway traffic road (source: Italian Association of Motorway and Tunnel Concessionaire Company, AISCAT) over the same period. Having confirmed the substantially linear dependency and the very high index of correlation of the variables, the respective elasticity function is studied and the elasticity index (relation between demand and GDP) for the four flow variables calculated. Our analysis shows an elasticity in excess of 1 for road traffic flows (1.71 for passenger traffic and 1.23 for freight traffic) and less than 1 for rail traffic (0.76 for passenger traffic and 0.81 for freight traffic). This means that the elasticity of the road traffic system is considerably higher (for every point of growth in GDP we have a 1.71 growth for passenger traffic and 1.23 for freight). In contrast with the analysis conducted by Leontieff for PGT of 1986 (for both the road and rail sectors systems), the elasticity of passenger flows is higher than that of freight flows in the road traffic sector (the data of 1986 indicate an elasticity of more than 1 for freight and less than 1 for passengers).