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

2 ABSTRACT The quantification of the freight movements occurring in each traffic zone disaggregated by supply chain and of the corresponding Origin-Destination trip tables connected with the urban delivery of goods, is essential to evaluate the effects of any city logistic policy in terms of vehicle congestion and polluting emissions, based on the assignment of truck flows to the road network. To this end in this paper we propose two innovative demand models: the first one for movement generation, the second one for trip distribution. The movement generation is addressed through an extension of category index models, which takes into account the hierarchy within the classification system of the economic activities, thus avoiding to aggregate the many classification codes into pre-specified groups. The trip distribution is addressed through an adaptation of gravity models, which takes into account that deliveries are organized into tours. 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.