Movement generation and trip distribution for freight demand modelling applied to city logistic

2 ABSTRACT The quantification of the freight movements occurring in each traffic zone, and then of the Origin-Destination trip tables due to the delivery of goods in the urban environment, is essential for evaluating the effects of any city logistic policy in terms of vehicle congestion and polluting emissions, based on the assignment of demand flows to the road network. To this end in the present article we propose two innovative demand models, the first one for movement generation, the second one for trip distribution. The movement generation will be addressed through a particular category index model, which takes into account the hierarchy and similarity among the different categories identified by the official tree-based classification of the economic activities, thus avoiding to aggregate the many categories into pre-specified groups. The trip distribution will be addressed through a specific gravitational model, which takes into account that pickups and deliveries (i.e., the generated movements) are organized into tours that begin and end at given portals (i.e., logistic centers, or access roads to town). This approach has been successfully applied to the case of Emilia-Romagna region in Italy, where an extensive campaign of surveys has permitted to calibrate both models for several towns and cities with various dimensions and vocations.